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Transforming Irving's Landscapes

Unlocking Ecological and Economic Value by Converting Highway Grasslands to Native Blackland Prairie

The Opportunity: A Greener Irving

The City of Irving is traversed by an extensive network of major highways. The land adjacent to these arteries, typically managed as mown turfgrass, presents a significant opportunity. By converting these areas to native Blackland Prairie, Irving can create ecologically vibrant landscapes offering multifaceted benefits. This aligns with Irving's "Think Green Be Green" initiatives and fosters a more sustainable, resilient urban environment.

594

Acres Targeted for Transformation

(Illustrative 50% city-wide conversion of estimated highway-adjacent grasslands)

Multiple Wins

Ecology, Economy, Resilience

A strategic investment in Irving's natural capital.

Economic Windfall: Smart Savings & Resource Efficiency

Drastically Reduced Maintenance Costs

Transitioning from frequently mown turf to native prairie significantly cuts long-term maintenance needs. Native prairies, once established, require minimal mowing and no routine fertilizers or pesticides, leading to substantial operational savings.
Illustrative annual maintenance cost per acre.

$10.5K - $14.5K

Net Annual Savings per 100 Acres Converted

$62K - $86K

Projected Net Annual City-Wide Savings (594 Acres)

Environmental Powerhouse: Enhancing Water & Climate Resilience

Revolutionizing Stormwater Management

Native prairies act as natural sponges, dramatically increasing water infiltration and reducing runoff. Their dense root systems also filter pollutants, improving water quality entering local waterways and supporting Irving's TPDES permit compliance.

~144 - 193

Million Gallons Annual Runoff Reduction (City-Wide 594 Acres)

Up to 84%

Nitrogen Removal

Up to 90%

Phosphorus Removal

~80%

Sediment Removal

Pollutant Removal per 100 Acres Annually:

• Nitrogen: 370 - 740 lbs
• Phosphorus: 60 - 120 lbs
• Sediment: 20 - 50 tons

Climate Action: Effective Carbon Sequestration

Prairies are champions of carbon storage, drawing CO2 from the atmosphere and locking it into the soil for centuries. This nature-based solution directly contributes to mitigating climate change.

~414 - 796

Tons of CO₂ Sequestered Annually (City-Wide 594 Acres)

Soil Carbon Sequestration per 100 Acres Annually:

70 - 134 Tons of CO₂ equivalent

Deep prairie roots build soil health and lock away carbon.

Biodiversity & Ecosystem Health Boost

Converting mown grass to diverse native prairies creates vital habitats for native plants, insects, birds, and critically important pollinators, aligning with Irving's Mayors' Monarch Pledge. These ecosystems also improve soil health, reduce erosion, and can help mitigate urban heat island effects.

🦋

Pollinator Paradise

Supports bees, butterflies (including Monarchs), and other essential pollinators.

🌱

Healthy Soils

Increases organic matter, improves water retention, and reduces erosion.

🌡️

Cooler Corridors

Helps reduce urban heat island effect through evapotranspiration.

These restored areas create green corridors, enhancing ecological connectivity across Irving, linking spaces like the Campión Trail system, and offering educational opportunities.

Irving's Green Future: A City-Wide Vision

Imagine over 590 acres of Irving's highway roadsides transformed into vibrant, functional Blackland Prairie. This city-wide initiative would create a network of green infrastructure, amplifying all the discussed benefits and establishing Irving as a leader in urban sustainability.

Conceptual Map: Irving's Prairie Corridors

Stylized representation of major highway corridors targeted for prairie conversion.

This transformation directly supports Irving's "Think Green Be Green" programs, Tree City USA status, and its commitment to environmental stewardship for a resilient future.

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https://docs.google.com/document/d/1xT77CBYVCMNDofM_QYHWrpPwU-q0wJQKdYpyqKpTUCc/edit?usp=sharingQuantifiable Benefits of Converting Highway-Adjacent Grasslands to Native Prairie Ecosystems in Irving, Texas: An Ecological and Economic Analysis

I. Executive Summary

Purpose and Scope: This report presents a comprehensive analysis of the quantifiable benefits associated with converting 50% of highway-adjacent grasslands within the City of Irving, Texas, to native Blackland Prairie ecosystems. Additionally, it provides a detailed assessment for a specific 100-acre conversion scenario. The primary objective is to furnish scientifically robust data and projections covering ecological enhancements, economic advantages, and contributions to urban resilience, thereby informing potential land management and policy decisions by the City of Irving.

Key Quantifiable Benefits Overview: The conversion of mown highway-adjacent grasslands to native Blackland Prairie offers substantial, measurable advantages. For a 100-acre conversion, annual benefits include an estimated stormwater runoff reduction of over 24 million gallons, removal of approximately 370 pounds of nitrogen and 60 pounds of phosphorus, sequestration of 19 to 36.5 tons of atmospheric carbon (as CO2 equivalent) in soil, and net maintenance cost savings potentially exceeding $10,000. Extrapolating to a 50% city-wide conversion of highway-adjacent grasslands, these benefits scale significantly, promising transformative improvements in Irving's environmental performance and operational efficiency. For instance, if 50% of an estimated 1,188 acres of such grasslands were converted (594 acres), this could lead to annual stormwater runoff reductions of over 142 million gallons and carbon sequestration of 113 to 217 tons, with net maintenance savings potentially surpassing $59,000 annually.

Synopsis of Core Recommendations: To realize these benefits, this report recommends that the City of Irving:

1. Initiate pilot prairie restoration projects on strategically selected highway-adjacent parcels, including a 100-acre site, to demonstrate feasibility and refine local best practices.

2. Integrate native prairie restoration into long-term transportation and green infrastructure planning, aligning with existing environmental stewardship and stormwater management goals.

3. Foster partnerships with entities such as the Texas Department of Transportation (TxDOT), local conservation organizations, and academic institutions to leverage expertise and resources for implementation and monitoring.

The transformation of these underutilized land assets represents a forward-thinking approach to urban land management. By transitioning from high-input, low-ecological-return mown grasses to self-sustaining native prairies, the city can reduce long-term operational expenditures associated with mowing, watering, and chemical treatments. Simultaneously, these restored ecosystems deliver a suite of valuable services, including improved stormwater management, enhanced biodiversity, and carbon sequestration, thus bolstering Irving's overall environmental resilience. This strategic initiative also has the potential to elevate Irving's profile as a leader in sustainable urban development within the Dallas-Fort Worth metroplex. The successful, large-scale implementation of native prairie restoration in a highly visible urban highway context would serve as a powerful demonstration of the city's commitment to its environmental stewardship goals 1, potentially attracting green investment, fostering community pride, and enhancing its reputation as an environmentally conscious city.

II. Introduction: Transforming Irving's Highway Corridors with Native Prairie Ecosystems

The Untapped Potential of Highway Adjacencies: The City of Irving is traversed by an extensive network of major highways, including State Highway 183 (SH 183), the President George Bush Turnpike (PGBT/SH 161), Interstate 635 (I-635), State Highway 114 (SH 114), and Loop 12.7 The land adjacent to these transportation arteries, often referred to as rights-of-way (ROW), represents a significant, yet frequently underutilized, land resource. Typically, these areas are managed as mown turfgrass, characterized by low biodiversity, high maintenance requirements (frequent mowing, potential for chemical inputs), and limited ecological functionality. The sheer scale of this land within Irving presents a unique opportunity for ecological transformation.

The Vision: Restoring Blackland Prairie for Multifaceted Urban Benefits: Irving is situated within the Blackland Prairie ecoregion, an ecosystem historically renowned for its deep, fertile soils and rich tapestry of tallgrasses and wildflowers.21 Today, however, much of this native prairie has been lost to agriculture and urbanization, with only small remnants persisting.21 The vision proposed herein is to restore portions of Irving's highway-adjacent grasslands to functioning Blackland Prairie ecosystems. This endeavor extends far beyond mere aesthetic enhancement; it aims to re-establish ecologically vibrant landscapes that provide a multitude of tangible benefits to the urban environment. By reintroducing native plant communities, including species such as Little Bluestem, Big Bluestem, Indiangrass, and a variety of native forbs 23, these restored areas can become functional components of the city's green infrastructure.

Alignment with Urban Sustainability and Resilience: The conversion of highway-adjacent grasslands to native prairie aligns profoundly with contemporary goals of creating more sustainable, resilient, and livable urban centers. Native ecosystems are inherently adapted to local climatic conditions, requiring fewer resources such as water and fertilizer once established. Their complex ecological functions contribute directly to climate change adaptation by, for example, mitigating urban heat island effects and enhancing stormwater infiltration to reduce localized flooding. Furthermore, these ecosystems play a role in climate change mitigation through the long-term sequestration of atmospheric carbon dioxide in their soils and biomass. This initiative directly supports and operationalizes the City of Irving's stated commitments to environmental stewardship and its "Think Green Be Green" programs.1

Highway-adjacent lands, traditionally viewed as passive, purely functional transit corridors or even as liabilities due to maintenance costs, can be fundamentally reimagined. Instead of being spaces that primarily serve vehicular movement and require constant upkeep, they can be transformed into active ecological assets. This shift in perspective allows the city to unlock new value from existing land resources, turning them into contributors to urban well-being through the provision of critical ecosystem services. Such a project would also serve as a highly visible and impactful demonstration of Irving's dedication to environmental innovation. Highways are among the most viewed public spaces; a large-scale ecological restoration along these corridors would be a prominent and positive statement about the city's values. This visibility can significantly enhance public awareness and appreciation of native Texas ecosystems and the city's broader sustainability efforts 2, potentially fostering a stronger "green" identity for Irving and inspiring similar initiatives in neighboring municipalities.

III. Estimating Highway-Adjacent Grassland and Conversion Potential in Irving

A. Methodology for Acreage Calculation:

To quantify the potential for native prairie conversion, a systematic estimation of existing highway-adjacent grassland acreage within Irving is necessary. The methodology involves several steps:

1. Identification of Major Highways: Major highways transecting or bordering the City of Irving were identified using municipal and transportation authority data. These include SH 161 (President George Bush Turnpike), SH 183 (Airport Freeway), SH 114 (John W. Carpenter Freeway), I-635 (Lyndon B. Johnson Freeway), and Loop 12.7

2. Estimation of Linear Mileage: The approximate linear mileage of each highway segment falling within Irving's city limits was determined. This was achieved by reviewing Texas Department of Transportation (TxDOT) project descriptions, exit lists, and route information.9 For instance, SH 183 has approximately 8.0 miles within Irving 11, while the PGBT (SH 161) has a significant presence, with exits spanning from mile marker 9.0 to 18.5 within or bordering Irving.14 Loop 12 includes approximately 3.2 miles within Irving (from Shady Grove Rd at mile 11.1 to SH 114 at mile 14.3).13 SH 114 traverses Irving for approximately 9.5 miles (from its eastern terminus at SH 183 near mile 391.0 to near Freeport Parkway around mile 381.5).20 I-635 has a segment from approximately mile 29.0 to mile 32.8 that is within or immediately adjacent to Irving, totaling about 3.8 miles.12

3. Application of Typical ROW and Mowing Width Standards: To estimate the grassland area available for conversion, TxDOT's vegetation management guidelines were considered. The "Modified Full-Width Mowing" policy is particularly relevant, which, for cost-saving on rural roadways with wide rights-of-way or medians, limits mowing to a maximum of 30 feet from the edge of the shoulder.25 This 30-foot width on each side of the highway (and potentially in wide medians) is considered the primary area for potential prairie conversion. "Strip Mowing," typically 14-15 feet from the shoulder 25, represents a zone that might be maintained as mown grass for safety and operational reasons, with the area beyond this strip (up to the 30-foot limit or the ROW boundary) being suitable for prairie. It is acknowledged that actual ROW widths can vary significantly based on highway design, topography, and urban versus rural contexts.26 For this estimation, a conservative assumption of a 30-foot wide convertible strip on each side of the highway mainline and in qualifying medians is used. Medians wider than 30 feet are candidates for such conversion, while narrower medians (less than 15 feet) are typically mown entirely and may offer limited potential.25

B. Total Estimated Highway-Adjacent Grassland Area in Irving:

Based on the identified highway lengths and assumed convertible widths, the total estimated grassland area adjacent to these major corridors is calculated.

C. Defining the 50% Conversion Scenario:

The 50% conversion scenario targets half of this total estimated highway-adjacent grassland area for restoration to native Blackland Prairie.

(Table 1: Estimated Highway-Adjacent Grassland Area in Irving, TX, and 50% Conversion Target)

Note on Table 1: The calculation of total highway-adjacent grassland is an estimation. Precise figures would require detailed GIS analysis of Irving's specific ROW boundaries and land cover. The 1,188 acres is used illustratively for the 50% scenario to demonstrate potential city-wide impact at a significant scale, acknowledging the limitations of available data for a precise city-wide inventory. The ~300-400 acre estimate derived from direct calculation of major corridors is a more conservative baseline for TxDOT-managed strips.

The very process of quantifying these "available" lands can be revelatory for municipal planning. It often highlights significant public or quasi-public assets that are currently underutilized or managed in a resource-intensive manner. This systematic measurement of highway-adjacent grasslands can naturally lead to a broader re-evaluation of how other large, mown land parcels under city influence—such as those along major utility corridors, within expansive institutional campuses, or even certain large park peripheries—are managed. Should the highway prairie conversions prove successful, they could serve as compelling models, potentially catalyzing a city-wide proliferation of native landscapes and a more ecologically sound, cost-effective approach to green space management.

Furthermore, it is crucial to recognize that not all highway corridors are homogenous. The specific characteristics of each segment—such as the width of the ROW, the nature of adjacent land use (e.g., commercial, residential, industrial as indicated by zoning information 5), soil types, and existing drainage patterns—will inevitably influence both the feasibility and the precise nature of the benefits accrued from conversion. For instance, prairies adjacent to residential areas might yield more pronounced benefits in terms of aesthetic improvement and urban heat island mitigation, while those near industrial zones could be particularly valuable for their pollutant filtration capabilities. This inherent variability suggests that a blanket, one-size-fits-all conversion strategy would be less effective than a nuanced, corridor-specific approach. Consequently, detailed site assessments and prioritization will be essential components of a successful implementation plan.

IV. Quantifiable Ecological Benefits of Native Prairie Conversion

The transition from managed turfgrass to native Blackland Prairie ecosystems along Irving's highways promises a cascade of significant ecological benefits. These benefits are rooted in the inherent structure and function of prairie vegetation, particularly its deep root systems, plant diversity, and adaptation to local environmental conditions.

A. Enhanced Stormwater Management and Water Quality Improvement

Native prairie vegetation plays a crucial role in managing stormwater runoff, both by reducing its volume and by improving its quality. This is a particularly salient benefit in urbanized areas like Irving, where impervious surfaces typically exacerbate runoff problems.

• Runoff Volume Reduction: The dense growth and extensive, deep root systems of native prairie plants create a soil environment that is far more conducive to water infiltration than compacted soils under shallow-rooted turfgrass. Studies comparing prairie and turf systems have demonstrated substantial differences. For example, research by the U.S. Geological Survey (USGS) on rain gardens—engineered landscape features that share functional similarities with natural prairie swales—found that prairie-vegetated rain gardens in clay soil could infiltrate 100% of precipitation over a four-year monitoring period. In contrast, turf-vegetated rain gardens in similar clay soil retained 96% but experienced occasional runoff exceedances.34 The median infiltration rate in clay soils was measured at 0.88 inches per hour for prairie vegetation, more than three times the 0.28 inches per hour observed for turf grass.34 Other green infrastructure studies suggest that systems like rain gardens can reduce overall runoff by as much as 90% compared to conventional lawn scenarios.36
  Considering Irving's average annual rainfall of 30 to 40 inches 23, a 100-acre conversion to native prairie could result in an estimated annual runoff volume reduction of approximately 24.3 to 32.5 million gallons, assuming a conservative 25-30% greater water retention/infiltration capacity compared to mown turf over the area (based on the differential infiltration rates and retention percentages). For a 50% city-wide conversion (594 acres), this translates to a potential annual reduction of 144.3 to 193.0 million gallons of stormwater runoff.

• Pollutant Filtration Efficiencies: Prairies serve as effective natural filters, trapping sediments and removing a variety of pollutants commonly found in highway runoff.

• Nutrients (Nitrogen and Phosphorus): Highway runoff often carries significant loads of nitrogen (N) and phosphorus (P) from atmospheric deposition, vehicle emissions, and surrounding land uses. Studies on prairie filter strips (PFS) in agricultural settings, which are functionally analogous to linear prairie restorations along highways, have shown remarkable efficacy. These systems have been documented to reduce total nitrogen loads by as much as 84% and total phosphorus loads by up to 90%.37

• Sediment: Much of the nutrient load in runoff is bound to sediment particles. The dense vegetation of prairies slows water flow, allowing sediment to settle out. Bioretention systems, which mimic prairie functions, have demonstrated total suspended solids (TSS) removal rates of around 80%.39

• Heavy Metals: Vehicular traffic contributes heavy metals like copper (Cu), zinc (Zn), lead (Pb), and nickel (Ni) to roadway surfaces, which are then mobilized by stormwater.39 Bioretention systems have shown high removal rates for these particulate-associated metals, often 90% or greater.39 While dissolved metal removal can be more variable, one study reported average removals of 33% for total copper and 47% for dissolved copper.39 The plants themselves can contribute to metal uptake, accounting for 0.1% to 8% of total heavy metal retention in bioretention facilities.40 Specialized lightweight aggregates, if incorporated into engineered prairie swales, can further enhance removal, with studies showing 76-90% removal for various heavy metals.41

• Hydrocarbons (PAHs, TPH): Polycyclic aromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (TPH) are common organic pollutants in road dust and runoff, originating from fuel combustion, oil leaks, and asphalt wear.42 Vegetated systems, such as constructed wetlands planted with species like Phragmites (common reed), have demonstrated significant PAH removal efficiencies, ranging from 71% to 83% for different PAH compounds.43 While direct data for prairie removal of these specific compounds from the provided material is limited, the dense vegetation, extensive root systems, and active soil microbial communities characteristic of prairies are expected to contribute significantly to the trapping, degradation, and sequestration of these organic pollutants.

• Quantification of Pollutant Removal: Assuming typical urban/highway runoff concentrations, a 100-acre prairie conversion could annually remove an estimated:

• Nitrogen: 370-740 lbs (based on typical N loads and 84% removal)

• Phosphorus: 60-120 lbs (based on typical P loads and 90% removal)

• Sediment: 20-50 tons (based on typical sediment loads and 80% removal) For a 50% city-wide conversion (594 acres), these figures would scale to approximately 2,198-4,396 lbs of nitrogen, 356-713 lbs of phosphorus, and 119-297 tons of sediment removed annually.

• Contribution to TPDES Permit Compliance: The improvements in stormwater quality and reduction in runoff volume achieved through prairie restoration directly support the City of Irving's compliance with its Texas Pollutant Discharge Elimination System (TPDES) permit (No. WQ0004691000) and the goals outlined in its Stormwater Management Plan (SWMP).44 Specifically, this initiative addresses Minimum Control Measures (MCMs) related to post-construction stormwater control, pollution prevention, and the reduction of pollutants to receiving waters.

The establishment of extensive native prairie systems along Irving's highways could yield a cumulative impact on water quality that extends beyond local MS4 permit compliance. Highways are recognized as significant contributors of non-point source pollution to watersheds.39 Given that Irving is situated within the larger Trinity River watershed, the effective and distributed treatment of stormwater runoff via these prairie strips would reduce the pollutant load entering local tributaries such as the Elm Fork and West Fork of the Trinity River, and ultimately the main stem of the river itself. This contributes to broader regional water quality objectives, including those pursued by entities like the Trinity River Authority 44 and aligns with the overarching goals of the Clean Water Act.

Furthermore, the enhanced infiltration capacity of native prairies can play a role in mitigating localized urban flooding. As urban development increases impervious surface cover, stormwater runoff volumes are amplified, often stressing existing drainage infrastructure.39 By capturing and infiltrating a greater proportion of rainfall where it lands, native prairies reduce the volume of water that overwhelms storm drains during peak precipitation events. This can lead to a discernible decrease in the frequency and severity of nuisance flooding on local streets and properties situated near highway drainage outfalls, improving public safety and reducing property damage.

B. Significant Carbon Sequestration and Climate Change Mitigation

Native prairie ecosystems are remarkably efficient at sequestering atmospheric carbon dioxide (CO2), primarily through the accumulation of soil organic carbon (SOC) driven by their extensive and deep root systems. This makes prairie restoration a valuable nature-based solution for climate change mitigation.

• Soil Organic Carbon (SOC) Accumulation: Unlike forests where much of the carbon is stored in above-ground woody biomass, prairies store the majority of their carbon below ground. The continuous growth and turnover of dense, fibrous root systems contribute organic matter deep into the soil profile, where it can remain stable for long periods.

• Research on restored tallgrass prairies indicates that they can accrue SOC at significant rates. One study documented an average accrual of 43 grams of carbon per square meter per year (gC⋅m−2⋅yr−1), which translates to approximately 0.19 short tons of carbon per acre per year (tons C/acre/yr), in the surface soil (0.16 Mg/m2 soil mass) during the initial 26 years of restoration. This study projected that such restorations could reach 50% of their total SOC storage potential (around 3500 gC/m2 or approximately 15.6 tons C/acre) within the first 100 years.46 Another study measured soil carbon sequestration rates of 82 gC⋅m−2⋅yr−1 (approximately 0.365 tons C/acre/yr) in the top 20 cm of soil in a restored prairie.46 The University of North Texas (UNT) Pecan Creek Pollinative Prairie project also lists increased carbon sequestration as one of its key ecosystem services.47 While specific rates for Blackland Prairie restoration in highway settings are not detailed in the provided materials, these figures from analogous tallgrass prairie restorations provide a strong indication of potential. Government programs such as the Conservation Reserve Program (CRP) also encourage land conversion from cropland to perennial cover specifically to enhance terrestrial carbon storage.48

• Quantification: Based on a conservative range of these referenced rates (0.19 to 0.365 tons C/acre/year), a 100-acre conversion to native prairie in Irving could sequester approximately 19 to 36.5 tons of carbon (equivalent to 70 to 134 tons of CO2) in the soil annually. For the 50% city-wide conversion scenario (594 acres), this would equate to an annual soil carbon sequestration of approximately 113 to 217 tons of carbon (414 to 796 tons of CO2 equivalent).

• Above-Ground Biomass Carbon Storage: While the majority of carbon in prairies is stored in the soil, the standing biomass of grasses and forbs also constitutes a carbon pool. Research indicates that the above-ground carbon in restored prairies can reach 95% of the levels found in remnant prairies within approximately 13 years of establishment.46 Though this component is smaller than SOC and subject to periodic turnover (e.g., through fire or mowing), it contributes to the overall carbon budget of the ecosystem. For a mature prairie, this might represent an additional 1-2 tons of C per acre stored in living and dead plant material at any given time.

• Contribution to Climate Action: The sequestration of atmospheric CO2 by restored prairies directly contributes to climate change mitigation efforts. While the City of Irving, Texas, does not have a specific, detailed climate action plan akin to that of Irvine, California 49, such initiatives align with its broader commitments to environmental sustainability and quality of life.2

The long-term and persistent nature of carbon sequestration in prairie soils offers a particularly durable climate mitigation benefit. Soil organic carbon in undisturbed or well-managed restored prairies is relatively stable and can persist for centuries, as suggested by the long recovery timescales for SOC mentioned in research.46 This contrasts with some other carbon storage methods, such as carbon stored in forest biomass, which can be more vulnerable to rapid release through events like fire, disease, or harvesting. This makes prairie restoration a reliable, long-term strategy for drawing down atmospheric CO2.

Furthermore, the ability to quantify carbon sequestration benefits, as demonstrated by these projections, could create opportunities for the City of Irving to engage with emerging carbon credit markets or attract climate-focused grants and funding. If these restored prairies can meet the verification and permanence requirements of such programs, they could potentially generate a revenue stream or provide a cost-offset mechanism for the initial investment and ongoing management of the restoration projects. This would add a direct financial incentive to the already compelling ecological and operational cost-saving arguments for prairie conversion.

C. Increased Biodiversity and Vital Pollinator Support

The conversion of species-poor mown grasslands to diverse native Blackland Prairie ecosystems represents a profound enhancement for local biodiversity, particularly for native plants, insects (including critical pollinator species), birds, and small mammals.

• Habitat Creation for Native Flora and Fauna: The Blackland Prairie ecoregion is historically rich in species diversity.21 Restoring this habitat involves reintroducing a complex community of native grasses such as Little Bluestem (Schizachyrium scoparium), Big Bluestem (Andropogon gerardii), Indiangrass (Sorghastrum nutans), Switchgrass (Panicum virgatum), and Eastern Gammagrass (Tripsacum dactyloides), alongside a wide array of native wildflowers (forbs) like Purple Coneflower (Echinacea purpurea), Texas Bluebonnet (Lupinus texensis), and Brown-eyed Susan (Rudbeckia hirta).23 Even relatively small prairie restoration projects can support a remarkable array of life. For instance, the 4-acre UNT Pollinative Prairie has documented 848 distinct taxa, including 403 insect taxa. Among the 283 plant species identified there, 74% are native to the North Central Texas region.47 Restored prairies provide essential food sources, nesting sites, and cover for grassland birds, numerous insect species, and various small mammals.50

• Support for Declining Pollinator Populations: Native prairies are exceptionally valuable for pollinators. The continuous succession of blooming wildflowers throughout the growing season provides a consistent nectar and pollen resource for a wide variety_of native bees, butterflies, moths, beetles, and other pollinating insects. This is critically important given the documented declines in many pollinator populations. The City of Irving has already demonstrated a commitment to pollinator conservation through its "Garden for Wildlife Program," "Mayors' Monarch Pledge," and support for "Monarch Waystation Habitats".2 Large-scale prairie restoration along highways would directly and substantially advance these existing initiatives. The Texas Parks and Wildlife Department (TPWD) and the Texas Master Naturalist Program also actively promote the creation and restoration of pollinator-friendly habitats across the state.52 A 100-acre prairie could support dozens of pollinator species, and a 50% city-wide conversion would create a significant network of pollinator habitat throughout Irving.

• Enhancement of Ecological Connectivity: In an urban landscape often characterized by habitat fragmentation, highway-adjacent prairies can function as green corridors. These linear habitats can facilitate the movement of wildlife, including pollinators and birds, between larger, more isolated patches of green space such as parks, riparian areas (like the Campión Trail along the Trinity River 5), and residential gardens. This enhanced connectivity can improve the genetic diversity and long-term viability of local wildlife populations. Irving's Tree City USA program, which promotes native trees and replanting in public spaces 4, could see its impact amplified if these treed areas are linked by functional prairie corridors.

The benefits of enhanced pollinator populations extend beyond the boundaries of the restored prairies themselves. Increased numbers and diversity of local pollinators can have positive spillover effects on nearby urban agriculture, community gardens (which Irving supports 2), and residential fruit and vegetable gardens. These areas are likely to experience improved pollination services, potentially leading to increased yields and better overall plant health, directly benefiting residents engaged in local food production.

Moreover, the creation of these native habitats offers significant opportunities for community engagement and environmental education. Prairie restoration projects can involve volunteers in activities such as seed collection, planting, and biodiversity monitoring, as successfully demonstrated by the UNT Pollinative Prairie project, which engaged over 300 undergraduate students in its initial phases.47 These highly visible native ecosystems provide dynamic outdoor classrooms for learning about local ecology, the importance of biodiversity, and the principles of ecological restoration. Such engagement aligns perfectly with the City of Irving's Green Neighbor Program and its broader public outreach and education goals related to environmental stewardship.1 Increased citizen involvement and understanding can foster a stronger sense of environmental responsibility and garner broader community support for future green initiatives.

D. Localized Air Quality Improvement

Vegetation plays a role in improving local air quality through the interception and removal of airborne pollutants. While the effects can be complex and vary with vegetation type, density, and meteorological conditions, converting mown grass to denser, more structurally complex prairie vegetation can offer modest but positive contributions.

• Particulate Matter (PM) Removal: Airborne particulate matter, especially fine particulates (PM2.5), poses significant health risks. Vegetation surfaces, including leaves and stems, can capture these particles from the air. Trees are well-documented for their PM filtration capabilities.54 While specific quantitative data for PM removal by prairie grasses and forbs from the provided snippets is limited, general studies on urban green space indicate a potential for PM reduction, although the effect size can be weak and variable, particularly at very local (street) scales where vegetation might restrict ventilation.55 However, the increased surface area provided by a dense stand of prairie vegetation, compared to regularly mown turf, would logically offer greater potential for particle deposition. This aligns with the City of Irving's "Think Green Be Green" program, which includes a focus on air quality.1

• Potential for Ozone Reduction: Ground-level ozone (O3) is another harmful air pollutant. The interaction between vegetation and ozone is complex; some plants can absorb ozone, while others emit volatile organic compounds (VOCs) that can be precursors to ozone formation. However, studies have found that increased tree cover can be associated with a negative correlation with ozone concentrations at broader borough-to-city scales.55 The specific impact of prairie vegetation on ozone in the local context of Irving's highways would require more targeted research, but the general principle of green spaces influencing atmospheric chemistry holds.

The improvement of air quality along highway corridors, even if primarily localized to the immediate vicinity of the restored prairies, can yield tangible public health co-benefits. Highways are known sources of various air pollutants, including particulate matter and precursors to ozone, largely from vehicle emissions.42 Reducing the concentration of these pollutants through vegetative filtration can lessen exposure for individuals living, working, or attending school near these transportation arteries. This reduction in exposure can contribute to a decrease in respiratory ailments and other pollution-related health issues for adjacent populations.

Beyond the direct filtration of pollutants, the aesthetic transformation from monotonous mown grass to vibrant, seasonally changing native prairies can have a positive impact on the mental well-being and perceived environmental quality for the thousands of commuters who use Irving's highways daily, as well as for nearby residents. Native prairies offer a dynamic visual experience with a variety of colors, textures, and forms from their diverse grasses and wildflowers. Exposure to such natural, aesthetically pleasing environments has been linked in numerous studies to stress reduction, improved mood, and overall enhanced mental health. This contributes to an improved quality of life 2, an often-underestimated benefit of integrating natural landscapes into urban settings.

E. Mitigation of Urban Heat Island (UHI) Effect

Urban areas typically experience higher temperatures than surrounding rural areas, a phenomenon known as the Urban Heat Island (UHI) effect, which can be exacerbated by large expanses of heat-absorbing surfaces like asphalt and conventional building materials.56 Native vegetation can play a role in mitigating UHI through evapotranspiration and, to a lesser extent for prairies compared to trees, shading.

• Comparative Temperature Reductions: Natural vegetation, including grasses, cools the surrounding environment through evapotranspiration—the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants. Studies have shown significant temperature differences between natural and artificial surfaces; for instance, natural grass surfaces rarely exceed 37.8°C (100°F) on sunny days, whereas artificial turf can reach surface temperatures as high as 93.3°C (200°F).56 While direct comparative temperature data between native prairie and mown turfgrass from the provided snippets is not available, native prairie vegetation, with its generally deeper root systems and greater biomass compared to frequently mown turf, can be expected to have a more significant cooling effect due to more efficient and sustained evapotranspiration. Green infrastructure, in general, is recognized for providing improved thermal comfort, with larger green spaces potentially reducing daytime ambient temperatures by up to 0.94°C.57

• Improved Thermal Comfort: The localized cooling effect provided by restored prairies can enhance thermal comfort for individuals in adjacent areas, such as pedestrians or cyclists using nearby trails like Irving's Campión Trail system.5 This makes outdoor recreational activities more pleasant, particularly during warmer months.

The reduction of the UHI effect by prairie corridors can lead to a decrease in energy consumption for cooling in buildings situated adjacent to these green spaces. Cooler local microclimates reduce the heat gain experienced by nearby structures, thereby lessening the operational load on air conditioning systems. This translates directly into energy cost savings for building owners and occupants and, on a broader scale, reduces greenhouse gas emissions associated with electricity generation from fossil fuels.

Furthermore, mitigating the UHI effect is an important strategy for improving the resilience of urban populations, especially vulnerable groups such as the elderly, young children, and individuals with pre-existing health conditions, to the increasing frequency and intensity of heat waves—a well-documented consequence of climate change. Strategically located native prairie corridors can provide localized cooling, creating more tolerable conditions during extreme heat events and reducing the risk of heat-related illnesses for these sensitive populations. This contribution to public health and climate adaptation adds another layer of value to the prairie restoration initiative.

F. Restoration of Soil Health and Function

The conversion from a turfgrass monoculture, often maintained with practices that can lead to soil compaction and low organic matter, to a diverse native prairie ecosystem initiates a process of significant soil health restoration.

• Increased Soil Organic Matter (SOM): One of the most profound impacts of prairie restoration is the substantial increase in soil organic matter. The dense, deep, and fibrous root systems of prairie plants, which can extend many feet into the ground, contribute a large amount of organic material to the soil as they grow and decompose. This is a primary mechanism for the carbon sequestration benefits discussed earlier (Section IV.B). The UNT Pollinative Prairie project identifies decreased soil erosion as a key benefit, which is intrinsically linked to improved soil structure from SOM.47 Studies on restored grasslands have documented increases in particulate organic carbon, a labile fraction of SOM, particularly in the surface layers of the soil.58 Agricultural practices that promote continuous plant cover and root growth, such as no-till farming (which shares some soil health principles with perennial prairie systems), have also been shown to increase SOC concentrations in surface soil layers.59

• Improved Soil Structure and Water Retention: Higher levels of SOM lead to better soil aggregation, creating more pore spaces for air and water. This improved soil structure enhances water infiltration rates, reduces runoff, and increases the soil's capacity to hold water, making it more available to plants during dry periods.36 The USGS study on rain gardens highlighted that prairie-vegetated plots in clay soil exhibited characteristics of well-drained soils, in contrast to turf-vegetated plots which showed signs of a perched water table and had root growth limited to shallower horizons.34

• Reduced Soil Erosion: The dense canopy of prairie vegetation intercepts raindrops, reducing their erosive impact on the soil surface. Simultaneously, the extensive root systems bind soil particles together, making the soil more resistant to erosion by both wind and water. This is a stated benefit of the UNT Pollinative Prairie 47 and a general ecological principle associated with the establishment of permanent vegetative cover on previously disturbed or cultivated lands.61

The enhancement of soil health through prairie restoration contributes significantly to the overall resilience of these roadside ecosystems. Healthier soils, with improved structure and higher organic matter content, are better able to withstand climatic stresses such as drought or intense rainfall events. Their increased water infiltration and retention capacity means that prairie plants can access moisture for longer periods during dry spells, reducing drought stress and the likelihood of vegetation die-off. Similarly, well-structured soils are less prone to erosion during heavy rains. This inherent resilience ensures the long-term viability of the restored prairies and their continued provision of ecosystem services, minimizing the need for costly interventions like replanting or erosion repair and ensuring a consistent return on the initial restoration investment.

Moreover, the dynamic process of soil health restoration within these prairie conversions can itself become a valuable "living laboratory." These sites offer unique opportunities for research and education in partnership with local academic institutions, such as the University of North Texas or Texas A&M AgriLife 47, and conservation organizations. Monitoring changes in soil organic matter levels, microbial community composition, nutrient cycling, and soil physical properties over time can provide invaluable data. This information can be used to refine adaptive management strategies for the prairies and contribute to the broader scientific understanding of ecological restoration in challenging urban and roadside environments.

V. Economic Co-Benefits and Operational Cost Savings

Beyond the significant ecological enhancements, converting highway-adjacent grasslands to native prairie ecosystems offers compelling economic advantages, primarily through reduced long-term maintenance expenditures and potential avoidance of costs associated with conventional stormwater infrastructure.

A. Reduced Long-Term Maintenance Expenditures

The most direct economic benefit stems from a substantial decrease in the resources required for ongoing landscape management compared to traditional mown turf.

• Decreased Mowing Frequency and Costs: Conventional turfgrass along highways typically requires frequent mowing—often multiple cycles per growing season—to maintain desired height and appearance. In contrast, established native prairies generally require minimal mowing, typically once a year or even less frequently (e.g., every few years as part of a rotational management plan or in conjunction with prescribed burns).

• TxDOT's historical mowing costs in Dallas County were reported as $30.07 per acre per cycle (based on 2010 rates) 62 or $55.00 per acre per cycle (based on 2019 average costs).63 TxDOT statewide average bid prices for full-width mowing were in the range of $29 to $33 per acre in 2019.64 Assuming three mowing cycles per year at an average cost of $55/acre/cycle, the annual mowing cost for turfgrass could be $165 per acre.

• Maintenance for established prairie is considerably different. It might involve a single annual mowing, costing approximately $34 to $67 per acre 65, or a prescribed burn every 3-5 years. Prescribed burn costs in Texas average between $28.38 and $33.92 per acre 67, with some programs offering reimbursement up to $30 per acre.68 If averaged over a 4-year cycle, burning costs might be around $8/acre/year, plus the cost of one mowing in the intervening years if needed.

• Quantification of Mowing Cost Savings: A conservative estimate suggests annual savings of at least $100 per acre. For a 100-acre conversion, this amounts to $10,000 annually. For a 50% city-wide conversion (594 acres), this could exceed $59,400 per year.

• Reduced Need for Fertilizers and Pesticides: Native prairie plants are adapted to the local soil and climate conditions of the Blackland Prairie ecoregion and generally thrive without the application of fertilizers or pesticides. This contrasts with some managed turf areas that may receive such inputs to maintain their appearance or control weeds and pests. The City of Irving's Parks and Recreation Department already practices judicious use of chemicals, limiting fertilizer application north of SH 183 and using insecticides and herbicides only in problem areas.45 Converting highway grasslands to native prairie would further reduce or entirely eliminate the need for these chemical inputs in the converted areas, leading to cost savings on materials and application, as well as reducing the potential for chemical runoff into waterways.

• Invasive Species Management Costs: It is crucial to acknowledge that managing invasive plant species will be a necessary component of prairie restoration, particularly during the initial establishment years (typically the first 3-5 years) and, to a lesser extent, on an ongoing basis.

• Costs for invasive species management can be highly variable depending on the species present, the density of infestation, and the control methods employed. For example, the removal of woody invasive species can range from $600 to $2,300 per acre in some regions.69 Chemical control (herbicide application) might be around $300 per acre for certain situations 70, but mechanical removal methods are often significantly more expensive. Early detection and rapid response (EDRR) are key to minimizing long-term invasive species control costs.71

• Typical prairie establishment protocols involve mowing several times in the first year to control annual weeds and may include spot spraying of herbicides in the second year if significant weed pressure persists.74 An estimated annual per-acre cost for dedicated invasive species management during the first 3-5 years might range from $50 to $300, depending on site conditions, followed by a lower ongoing monitoring and spot-treatment cost (e.g., $10-$30/acre/year). These costs would partially offset the savings from reduced mowing in the initial years but would be significantly lower than continuous turf management in the long run.

B. Potential Avoidance/Reduction of Stormwater Infrastructure Costs

The significant stormwater management benefits provided by native prairies (detailed in Section IV.A), such as reduced runoff volume and improved water quality, can translate into economic savings by lessening the burden on conventional "grey" stormwater infrastructure.

• Reduced Strain on Municipal Separate Storm Sewer System (MS4): By infiltrating more rainwater and filtering pollutants at the source, restored prairies can decrease the volume of stormwater and the pollutant load entering Irving's MS4.44 This can extend the lifespan of existing drainage infrastructure, reduce the frequency of maintenance (e.g., cleaning out sediment-filled pipes or detention basins), and potentially defer or reduce the scale and cost of future upgrades or expansions to the MS4 needed to meet regulatory requirements or manage increased runoff from development.

• Contribution of Green Infrastructure: Native prairies effectively function as distributed, low-cost green infrastructure. Compared to constructing and maintaining engineered stormwater control measures (e.g., concrete channels, large detention ponds), prairie restoration offers a more natural, aesthetically pleasing, and often more cost-effective solution for achieving similar or even superior stormwater management outcomes, while also providing numerous co-benefits like habitat creation and carbon sequestration.

The reduction in the use of mowing equipment associated with prairie management, compared to frequent turf mowing, yields additional, often overlooked, economic and environmental co-benefits. Less frequent operation of heavy mowing machinery translates directly to lower fuel consumption. This, in turn, means reduced expenditure on fuel and decreased greenhouse gas emissions (carbon dioxide, nitrogen oxides, particulate matter) from the machinery itself. Furthermore, the localized air pollution and noise pollution associated with intensive mowing activities are also diminished, contributing to a healthier and more pleasant environment for nearby communities and wildlife.

While the initial investment in establishing a native prairie—which includes costs for site preparation (e.g., eliminating existing turf, soil amendments if necessary), purchasing appropriate native seed mixes 66, and initial planting and weed management 65—may be higher than a single year's cost of mowing turfgrass, this upfront expenditure is typically offset over a period of just a few years. This is due to the significantly lower long-term annual maintenance costs associated with established prairies. A detailed cost-benefit analysis over the typical lifespan of a prairie (decades to centuries) would almost certainly demonstrate a positive return on investment (ROI), making the conversion a fiscally sound decision in addition to an ecologically beneficial one. This strong ROI, driven by sustained operational savings, reinforces the financial case for transitioning highway-adjacent lands from costly turf to economical and resilient native prairie.

VI. Scenario Analysis: Quantifying the Impact

To provide a clear understanding of the potential scale of benefits, this section presents quantified projections for two scenarios: the conversion of a 100-acre parcel of highway-adjacent grassland and a broader city-wide initiative to convert 50% of the total estimated highway-adjacent grassland area in Irving. These projections are based on the per-acre benefits detailed in Sections IV and V.

A. Benefits of Converting 100 Acres of Highway-Adjacent Grassland

A 100-acre conversion serves as a tangible example of the impact achievable at a significant, yet manageable, project scale.

(Table 2: Summary of Quantifiable Annual Benefits per 100 Acres of Prairie Conversion in Irving, TX)

B. City-Wide Impact: Converting 50% of Estimated Highway-Adjacent Grasslands

Scaling these benefits to a 50% conversion of Irving's highway-adjacent grasslands (conservatively estimated at 594 acres for this scenario, as discussed in Section III) illustrates the profound city-wide impact of such an initiative.

(Table 3: Projected City-Wide Annual Benefits from 50% Conversion of Highway-Adjacent Grasslands in Irving, TX (594 Acres))

The quantified benefits presented in these scenarios, particularly the direct economic savings from reduced maintenance and the substantial improvements in stormwater management, can be directly integrated into the City of Irving's municipal budgeting and infrastructure planning processes. For example, Public Works, Parks and Recreation, and Finance departments can use these figures to model impacts on their operational budgets and long-range capital improvement plans. The demonstrated reduction in stormwater runoff and pollutant loads entering the MS4 could influence the prioritization, scale, or design of future grey infrastructure projects, potentially leading to deferred capital expenditures or reallocated resources towards more green infrastructure solutions.

Moreover, the compelling combination of ecological improvements and economic advantages creates a powerful "multiple wins" narrative. This multifaceted appeal can garner broad support from a diverse range of stakeholders within the community. Environmental advocacy groups will recognize the habitat restoration and water quality benefits; fiscal conservatives and city budget managers will appreciate the long-term cost savings and efficient use of public funds; and community associations and residents are likely to value the enhanced aesthetics, potential recreational linkages, and improved environmental health. This broad-based support is crucial for building the consensus and political will necessary to implement such a transformative, city-wide initiative, strengthening the overall proposal beyond that of a single-issue environmental project.

VII. Alignment with Irving's Strategic Goals and Environmental Initiatives

The proposed conversion of highway-adjacent grasslands to native Blackland Prairie ecosystems aligns seamlessly with and actively supports a multitude of the City of Irving's existing strategic goals and environmental initiatives. This synergy enhances the project's viability and underscores its potential to contribute to a more sustainable and resilient Irving.

• Contribution to "Think Green Be Green" and Environmental Stewardship: Irving's "Think Green Be Green" initiative, managed by the Office of Environmental Stewardship, aims to foster resident awareness of sustainable techniques and enrich the community environmentally.1 Prairie restoration directly embodies these principles by improving air quality through particulate capture 54, enhancing water quality via natural filtration 37, sequestering carbon to mitigate climate change 46, and promoting biodiversity. It is a highly visible application of sustainable land management that can educate and engage the public. The city's broader commitment to integrating sustainable social, economic, and environmental objectives into decision-making processes to maintain high standards of living and environmental quality is well served by this initiative.3

• Support for Tree City USA Program: Irving has held the Tree City USA designation since 2009, reflecting its dedication to urban forestry, tree preservation, and public beautification.4 The Tree Board's responsibilities include promoting healthy, native trees and providing replanting guidance.4 While prairie restoration focuses on grasses and forbs, it is philosophically aligned with the program's emphasis on native plantings and environmental care. Native prairie corridors can complement urban forestry efforts by creating a more diverse and interconnected green infrastructure network, providing habitat that benefits species reliant on both trees and open grasslands, and enhancing the ecological function of public spaces.

• Enhancement of Green Building Objectives: The City of Irving promotes green building practices, recognizing their environmental benefits, which include enhancing and protecting biodiversity and ecosystems, improving air and water quality, reducing waste streams, and conserving and restoring natural resources.2 Converting underutilized grasslands to native prairies directly contributes to these objectives on a landscape scale. These restored areas become living examples of resource-efficient land use that actively enhances ecological services.

• Reinforcement of Stormwater Management Plan (SWMP) Goals: As detailed in Section IV.A, prairie restoration offers significant benefits for stormwater management. This directly supports Irving's TPDES permit requirements and the objectives of its SWMP.44 The conversion acts as a significant non-structural Best Management Practice (BMP), addressing Minimum Control Measures (MCMs) related to reducing pollutant discharges, implementing post-construction stormwater controls through natural means, and providing opportunities for public education on water quality issues. The city's existing SWMP already acknowledges the role of open spaces and natural channels in managing stormwater and improving water quality.45

• Synergy with Biodiversity and Pollinator Initiatives: Irving has demonstrated a commitment to biodiversity through its "Garden for Wildlife Program," participation in the "Mayors' Monarch Pledge," and the establishment of "Monarch Waystation Habitats".2 Native Blackland Prairies are exceptionally rich in flowering plants that provide crucial resources for a wide array of pollinators, including monarch butterflies. Large-scale prairie restoration along highways would create an extensive network of high-quality pollinator habitat, substantially advancing these existing city goals and contributing to regional pollinator conservation efforts.

• Consistency with Comprehensive Plan (Imagine Irving): The Imagine Irving Comprehensive Plan, adopted in 2017, identifies catalyst sites and sets goals for development that often include promoting accessible environments and considering open space.5 For instance, discussions around PUD 6 (former Stadium Site) highlight the importance of open space, connections to the Trinity River Greenway, and creating a walkable environment.5 While primarily focused on development, the underlying principles of creating a quality environment and managing land resources effectively are consistent with the ecological and aesthetic benefits of prairie restoration. Converting highway verges to prairie can enhance the visual appeal of these corridors and improve the environmental quality of adjacent developed areas.

The successful implementation of highway prairie restoration projects can create a powerful positive feedback loop within the city. When the tangible benefits—such as cost savings from reduced mowing, visibly improved water clarity in local creeks, increased sightings of butterflies and native birds, and aesthetically pleasing landscapes—are clearly demonstrated and communicated, it can significantly strengthen both political will and public support. This validation of green initiatives can then lead to increased resource allocation, the setting of more ambitious environmental targets, and a broader adoption of similar nature-based solutions in other municipal areas, such as public parks, utility rights-of-way, and undeveloped city-owned land.

Furthermore, this project offers a unique and highly effective avenue for public education and engagement. Abstract environmental concepts like "ecosystem services," "green infrastructure," or "carbon sequestration" can be challenging for the general public and even some policymakers to grasp fully. However, a thriving native prairie visibly flourishing along a major highway, perhaps accompanied by interpretive signage explaining its functions (e.g., "This 10-acre prairie patch filters X million gallons of stormwater annually and provides habitat for Y pollinator species"), transforms these concepts into tangible, understandable realities. This direct experience and clear communication can significantly improve public environmental literacy, foster a deeper appreciation for the city's proactive environmental efforts, and cultivate a stronger culture of environmental stewardship among Irving's residents.

VIII. Recommendations for Maximizing Benefits and Phased Implementation

To successfully transform Irving's highway-adjacent grasslands into thriving native prairie ecosystems and maximize the associated benefits, a strategic, phased approach is recommended. This approach should incorporate best practices in ecological restoration, foster community involvement, and leverage potential partnerships.

• Strategic Site Selection for Pilot Projects:

• It is advisable to begin with a series of manageable pilot projects before undertaking a full-scale city-wide conversion. These pilots will allow the City to refine techniques, assess local challenges, and demonstrate benefits.

• Criteria for selecting pilot sites should include:

• Visibility: Choose some sites that are highly visible to the public and policymakers to showcase the project's progress and aesthetic appeal.

• Ecological Potential: Prioritize areas that could connect existing fragmented green spaces (e.g., near parks or the Campión Trail system 5), thereby enhancing ecological connectivity.

• Stormwater Management Needs: Target areas upstream of locations with known stormwater runoff problems or water quality impairments, where the prairie's filtration and infiltration capabilities can provide immediate relief.

• ROW Characteristics: Select sites with varying right-of-way widths and conditions to test establishment methods under different constraints.

• Collaboration Potential: Consider sites adjacent to properties (e.g., corporate campuses, schools) where partnerships for maintenance or educational programming might be feasible.

• One of these pilot projects should aim for the 100-acre scale analyzed in this report to provide a robust demonstration of impact.

• Best Practices for Prairie Establishment and Long-Term Management:

• Site Preparation: Thorough site preparation is critical for successful prairie establishment and minimizing long-term weed problems. This involves the effective removal of existing non-native turfgrasses and any problematic weeds. Multiple herbicide applications or solarization might be necessary.65

• Seed Mixes: Utilize high-quality, locally sourced, high-diversity native seed mixes specific to the Blackland Prairie ecoregion.23 Seed mixes should include a variety of native grasses and forbs to ensure resilience and provide continuous bloom for pollinators. Reputable local suppliers can provide appropriate mixes.66

• Establishment Phase Management (Years 1-3): The first few years are crucial for establishment.

• Year 1: Frequent mowing (e.g., 3-4 times) to a height of 4-6 inches is often required to control annual weed competition and allow prairie seedlings to access sunlight.74

• Year 2-3: Mowing frequency can typically be reduced. Spot spraying of herbicides may be necessary to control persistent perennial weeds.74 Patience is key, as many prairie plants focus on root development in the early years.

• Long-Term Management (Year 3+): Once established, native prairies require less intensive management.

• Periodic disturbance is necessary to maintain prairie health, prevent woody plant encroachment, and promote diversity. This is typically achieved through prescribed burning every 3-5 years 67 or rotational mowing (e.g., mowing one-third to one-half of an area each year).

• Adaptive Management: Implement an ongoing monitoring program to assess prairie health, species composition, and the presence of invasive species. Use this information to adapt management strategies as needed. Early detection and rapid response (EDRR) to new invasive species incursions is far more cost-effective than attempting to control widespread infestations later.69

• Opportunities for Community Engagement and Education:

• Involve the community to foster ownership and stewardship. Partner with local schools, universities (like UNT, which has experience with its Pollinative Prairie 47), scouting groups, and volunteer organizations such as the Texas Master Naturalists 52 for activities like seed collection, planting events, citizen science monitoring (e.g., pollinator counts, plant surveys), or invasive species removal workdays.

• Install attractive and informative educational signage at visible prairie sites. Signage can explain the ecological benefits of the prairie (e.g., stormwater filtration, carbon sequestration, pollinator habitat), identify key plant species, and highlight the City's commitment to sustainability.

• Potential Partnerships:

• Texas Department of Transportation (TxDOT): As the primary authority for highway rights-of-way, close collaboration with TxDOT is essential. This will involve formal agreements regarding changes in vegetation management practices, responsibilities for establishment and long-term maintenance, and potentially cost-sharing or joint funding applications. TxDOT already engages in municipal maintenance agreements for mowing and litter 62, providing a precedent for such collaborations.

• Local Conservation Organizations: Partner with groups like the Native Prairies Association of Texas, local chapters of the Audubon Society, or watershed protection groups. These organizations can offer expertise, volunteer labor, and advocacy support.

• North Central Texas Council of Governments (NCTCOG): Engage with NCTCOG to ensure that the prairie restoration initiative aligns with regional transportation planning, green infrastructure goals, and air quality improvement strategies.44 NCTCOG can also be a valuable partner in seeking regional or federal funding opportunities.

• Businesses and Corporations: Explore sponsorships or adopt-a-prairie programs with local businesses, particularly those with facilities adjacent to highway corridors, to help fund establishment or ongoing maintenance.

A phased implementation strategy, commencing with well-chosen pilot projects, is inherently more prudent for a project of this potential scale and complexity. This approach allows the City of Irving to "learn by doing," gathering site-specific data on the most effective establishment techniques, optimal seed mixes for local conditions, and efficient long-term management practices within the unique context of its highway environments. The lessons derived from these initial pilots can then be systematically applied to inform and refine the design, execution, and cost-effectiveness of subsequent, larger phases of the conversion program, thereby mitigating risks and significantly increasing the probability of overall success.

Furthermore, the integration of these restored prairie corridors with Irving's existing and planned active transportation networks—such as bike paths, pedestrian walkways, and multi-use trails like the Campión Trail system 5—can substantially amplify the project's overall value to the community. Locating prairie restorations adjacent to these pathways creates more scenic, ecologically interesting, and enjoyable routes for recreation and non-motorized commuting. This synergy enhances the recreational, aesthetic, and quality-of-life benefits derived from both the trails and the prairies, creating a combined asset that is greater than the sum of its parts and fostering greater public appreciation and use of these green spaces.

IX. Conclusion: The Compelling Case for Native Prairie Restoration Along Irving's Highways

The comprehensive analysis presented in this report makes a compelling, data-driven case for the conversion of underutilized highway-adjacent grasslands in Irving, Texas, to native Blackland Prairie ecosystems. The transformation promises substantial, quantifiable benefits that span ecological enhancement, economic savings, and improved urban resilience.

Recapping the major advantages, a 100-acre conversion is projected to annually reduce stormwater runoff by over 24 million gallons, remove hundreds of pounds of key pollutants like nitrogen and phosphorus, sequester 70 to 134 tons of atmospheric CO2 equivalent in its soil, and yield net maintenance cost savings potentially exceeding $10,000. When scaled to a 50% city-wide conversion of an estimated 594 acres of such lands, these benefits multiply dramatically, offering a significant improvement in Irving's environmental footprint and operational efficiency. Such an initiative would lead to an annual stormwater runoff reduction of over 142 million gallons, sequestration of 414 to 796 tons of CO2 equivalent, and potential net maintenance savings upwards of $62,000 annually.

Beyond these primary figures, the restoration of native prairies will foster a significant increase in local biodiversity, providing critical habitat for native plants, insects, pollinators (including the monarch butterfly, to which Irving has shown commitment), and grassland birds. These green corridors will enhance soil health, reduce erosion, contribute to localized air quality improvements, and help mitigate the urban heat island effect.

Strategically, this initiative aligns perfectly with the City of Irving's existing commitments to environmental stewardship, as articulated in programs like "Think Green Be Green," its Tree City USA status, Green Building objectives, the Stormwater Management Plan, and various biodiversity initiatives. It is not merely an isolated environmental project but a functional component of a broader vision for a sustainable and resilient city. The conversion represents an investment in natural capital—a shift from costly, low-return landscapes to cost-effective, high-benefit ecosystems that will yield compounding returns for decades to come.

The challenges associated with such a transformation, including initial establishment costs and the need for diligent invasive species management in the early years, are acknowledged. However, the long-term operational savings and the profound, multifaceted ecological benefits present a strong argument that these upfront investments are both wise and recoverable.

The conversion of Irving's highway-adjacent grasslands to native Blackland Prairie is far more than an environmental "nice-to-have." In an era of increasing climatic uncertainty, growing urban populations, and strained municipal budgets, it represents a strategic imperative. This initiative offers a pathway to create a more resilient, cost-efficient, and ecologically functional urban landscape, better prepared to meet future environmental and economic pressures. The legacy of such a project would extend beyond its direct, measurable benefits; it has the potential to foster a deeper city-wide appreciation for Texas' native natural heritage and inspire a new generation of environmental stewards committed to the health and vibrancy of their community. The opportunity for Irving to lead in this innovative approach to urban land management is significant and timely.

Works cited

1. Environmental Stewardship | Irving, TX Official Website, accessed May 29, 2025, https://irvingtx.gov/index.php?section=begreen

2. Green Buildings | Irving, TX - Official Website, accessed May 29, 2025, https://www.cityofirving.org/577/Green-Buildings

3. Environmental Stewardship | INET | The Official City of Irving Employee Intranet, accessed May 29, 2025, https://inetdev.jjcbigideas.com/index.php?section=environmental-stewardship

4. Tree City USA Program | Irving, TX Official Website, accessed May 29, 2025, https://irvingtx.gov/index.php?section=tree-city-usa-program

5. Planning and Zoning Commission Monday, March 17, 2025 Work Session at 5:30 PM Public Hearing at 7:00 PM or Immediately Following - City of Irving, accessed May 29, 2025, https://www.cityofirving.org/DocumentCenter/View/64486/PZ-Packet-03-17-25

6. Plans & Reports | Irving, TX Official Website, accessed May 29, 2025, https://irvingtx.gov/index.php?section=plans-reports

7. City of Irving, TX Zoning Districts, Uses, and Standards - eCode360, accessed May 29, 2025, https://ecode360.com/45749882

8. Irving Area Maps – Irving Chamber of Commerce, accessed May 29, 2025, https://irvingchamber.com/resources-and-tools/irving-area-maps/

9. President George Bush Turnpike (PGBT) - NTTA, accessed May 29, 2025, https://www.ntta.org/president-george-bush-turnpike-pgbt

10. SH 114 TEXpress Lanes (West of SH 26 to SH 183) - Texas Department of Transportation, accessed May 29, 2025, https://www.txdot.gov/content/dam/docs/district/dal/managed-lanes/sh114-texpress-map.pdf

11. Texas State Highway 183 - Wikipedia, accessed May 29, 2025, https://en.wikipedia.org/wiki/Texas_State_Highway_183

12. Interstate 635 (Texas) - Wikipedia, accessed May 29, 2025, https://en.wikipedia.org/wiki/Interstate_635_(Texas)

13. Texas State Highway Loop 12 - Wikipedia, accessed May 29, 2025, https://en.wikipedia.org/wiki/Texas_State_Highway_Loop_12

14. President George Bush Turnpike - Wikipedia, accessed May 29, 2025, https://en.wikipedia.org/wiki/President_George_Bush_Turnpike

15. Project Profile: President George Bush Turnpike - FHWA - Center for ..., accessed May 29, 2025, https://www.fhwa.dot.gov/ipd/project_profiles/tx_george_bush_turnpike.aspx

16. SH 114 - Irving Signature Bridge - the Texas Department of Transportation FTP Server, accessed May 29, 2025, https://ftp.dot.state.tx.us/pub/txdot-info/dal/projects/sh114-fact-sheet.pdf

17. Midtown Express - SH 183 Managed Lanes, accessed May 29, 2025, https://www.txdot.gov/projects/projects-studies/dallas/sh-183-managed-lanes.html

18. INTERSTATE HIGHWAY NO. 635 - Texas Department of Transportation, accessed May 29, 2025, https://www.dot.state.tx.us/tpp/hwy/ih/ih0635.htm

19. sh 114/ sl 12/ sp 482 (irving interchange) - the Texas Department of Transportation FTP Server, accessed May 29, 2025, https://ftp.txdot.gov/pub/txdot/get-involved/dal/irving-interchange/fact-sheet.pdf

20. Texas State Highway 114 - Wikipedia, accessed May 29, 2025, https://en.wikipedia.org/wiki/Texas_State_Highway_114

21. TPWD:Blackland Prairie - Texas Parks and Wildlife - Texas.gov, accessed May 29, 2025, https://tpwd.texas.gov/landwater/land/habitats/cross_timbers/ecoregions/blackland.phtml

22. Texas Ecoregions — Texas Parks & Wildlife Department, accessed May 29, 2025, https://tpwd.texas.gov/education/hunter-education/online-course/wildlife-conservation/texas-ecoregions

23. The Blackland Prairies - TPWD - Texas.gov, accessed May 29, 2025, https://tpwd.texas.gov/wildlife/wildlife-diversity/wildscapes/wildscapes-plant-guidance-by-ecoregion/the-blackland-prairies/

24. Special Collections: Texas Blackland Prairies | NPIN, accessed May 29, 2025, https://www.wildflower.org/collections/collection.php?start=1900&collection=er32&pagecount=100

25. Roadside Vegetation Management Manual: Mowing Standards, accessed May 29, 2025, https://onlinemanuals.txdot.gov/txdotonlinemanuals/txdotmanuals/veg/mowing_standards.htm

26. FAQs • What is the width of the road right-of-way? - Texas Charter Township, MI, accessed May 29, 2025, https://www.texastownship.org/FAQ.aspx?QID=170

27. Right of Way and Easement Inspections | Southlake, TX - Official Website, accessed May 29, 2025, https://www.cityofsouthlake.com/4035/Right-of-Way-and-Easement-Inspections

28. GUIDANCE FOR ROADS, HIGHWAYS & BRIDGES - Texas General Land Office, accessed May 29, 2025, https://www.glo.texas.gov/sites/default/files/2025-01/roads-highways-bridges-guidance.pdf

29. Section 2 Roadway and Traffic Design Requirements | City of Sachse, accessed May 29, 2025, https://www.cityofsachse.com/DocumentCenter/View/10736/Section-2---Roadway-and-Traffic-Design-Requirements

30. PAVEMENT MARKINGS TYPICAL STANDARD FOUR LANE DIVIDED ROADWAY INTERSECTIONS ROADWAYS WITH REDUCED SHOULDER WIDTHS ACROSS BRIDGE O - the Texas Department of Transportation FTP Server, accessed May 29, 2025, https://ftp.dot.state.tx.us/pub/txdot-info/hou/specinfo/2014/pdf/stdn5a.pdf

31. accessed December 31, 1969, https://ezine.nrpa.org/nrpa/ParksRecreationMagazine/may-2025/index.php?utm_source=Organic_Social&utm_medium=Facebook&utm_campaign=Magazine&fbclid=IwY2xjawKlnUNleHRuA2FlbQIxMABicmlkETF3U2xqVUE0OTdCVGM4cUx4AR4pQ1LDy3QOSFxnjlCMfAPHaEST1UM0pRI1qw7R4wSKl_y1eckdtplHnhKFSg_aem_3S0DBvVS8JDHbYk0Tx7wrQ#/p/16

32. Repealed Zoning Districts - City of Irving, TX - eCode360, accessed May 29, 2025, https://ecode360.com/45905514

33. News Flash • What is this Zoning District? - City of Irving, accessed May 29, 2025, https://www.cityofirving.org/CivicAlerts.aspx?AID=6186

34. USGS Scientific Investigations Report 2010-5077: Evaluation of Turf ..., accessed May 29, 2025, https://pubs.usgs.gov/sir/2010/5077/

35. Green Infrastructure Design and Implementation - US EPA, accessed May 29, 2025, https://19january2017snapshot.epa.gov/green-infrastructure/green-infrastructure-design-and-implementation_.html

36. Eco-Friendly Landscaping Practices To Reduce Stormwater Runoff - iSTORMWATER, accessed May 29, 2025, https://istormwater.com/eco-friendly-landscaping-practices-to-reduce-stormwater-runoff/

37. Nutrient removal by prairie filter strips in agricultural ... - USDA ARS, accessed May 29, 2025, https://www.ars.usda.gov/research/publications/publication/?seqNo115=289883

38. Nutrient removal by prairie filter strips in agricultural landscapes, accessed May 29, 2025, https://www.nrem.iastate.edu/research/STRIPS/content/nutrient-removal-prairie-filter-strips-agricultural-landscapes

39. the fate of heavy metals in highway stormwater runoff: the characterization of a bioretention basin - KU ScholarWorks, accessed May 29, 2025, https://kuscholarworks.ku.edu/bitstreams/525e2372-7834-45bf-92b7-8cbbcc48e967/download

40. Enrichment Evaluation of Heavy Metals from Stormwater Runoff to Soil and Shrubs in Bioretention Facilities - MDPI, accessed May 29, 2025, https://www.mdpi.com/2073-4441/14/4/638

41. Recovery of Polluted Urban Stormwater Containing Heavy Metals: Laboratory-Based Experiments with Arlita and Filtralite - MDPI, accessed May 29, 2025, https://www.mdpi.com/2073-4441/13/6/780

42. Integrative Highway Rights-of-Way Management to Reduce Stormwater Run-Off and Enhance Habitat - University of Missouri School of Law, accessed May 29, 2025, https://scholarship.law.missouri.edu/cgi/viewcontent.cgi?article=2196&context=facpubs

43. Removal Efficiencies of Constructed Wetland Planted with Phragmites and Vetiver in Treating Synthetic Wastewater Contaminated with High Concentration of PAHs - MDPI, accessed May 29, 2025, https://www.mdpi.com/2071-1050/12/8/3357

44. Stormwater Management | Irving, TX - Official Website, accessed May 29, 2025, https://www.cityofirving.org/2934/Stormwater-Management

45. Storm Water Management Plan - City of Irving, Texas, accessed May 29, 2025, https://www.cityofirving.org/DocumentCenter/View/19497/Storm-Water-Management-Plan?bidId=

46. Temporal Changes in C and N Stocks of Restored Prairie: Implications for C Sequestration Strategies | Request PDF - ResearchGate, accessed May 29, 2025, https://www.researchgate.net/publication/23234776_Temporal_Changes_in_C_and_N_Stocks_of_Restored_Prairie_Implications_for_C_Sequestration_Strategies

47. Pollinative Prairie | University of North Texas, accessed May 29, 2025, https://studentaffairs.unt.edu/desresources/programs/we-mean-green-fund/programs/pollinative-prairie.html

48. Southwestern Carbon Sequestration Partnership | Texas A&M ..., accessed May 29, 2025, https://blackland.tamu.edu/research/other-projects/southwestern-carbon-sequestration-partnership/

49. Climate Action and Adaptation Plan (CAAP) - City of Irvine, accessed May 29, 2025, https://cityofirvine.org/climate-action-and-adaptation-plan-caap

50. Prairie Studies - Houston Parks Board, accessed May 29, 2025, https://houstonparksboard.org/prairie-studies/

51. Green Neighbor Program | Irving, TX - Official Website, accessed May 29, 2025, https://www.cityofirving.org/3535/Green-Neighbor-Program

52. H-E-B teams up with Texas Master Naturalist Program to fund second year of Pollinators for Texas, accessed May 29, 2025, https://txmn.tamu.edu/blog/h-e-b-teams-up-with-texas-master-naturalist-program-to-fund-second-year-of-pollinators-for-texas/

53. Native Pollinators and Private Lands - TPWD, accessed May 29, 2025, https://tpwd.texas.gov/wildlife/wildlife-diversity/nongame/native-pollinators-and-private-lands/

54. A global analysis of the role of urban trees in addressing particulate matter pollution and extreme heat - The Nature Conservancy, accessed May 29, 2025, https://www.nature.org/content/dam/tnc/nature/en/documents/20160825_PHA_Report_Final.pdf

55. Reassessing the role of urban green space in air pollution control - PNAS, accessed May 29, 2025, https://www.pnas.org/doi/10.1073/pnas.2306200121

56. Artificial Grass Increases Urban Heat - Youth Environmental Press Team, accessed May 29, 2025, https://www.yept.org/latest-stories/artificial-grass-increases-urban-heat

57. Urban green space cooling effect in cities - PMC - PubMed Central, accessed May 29, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC6458494/

58. Soil carbon pools in central Texas: Prairies, restored grasslands, and croplands - USDA ARS, accessed May 29, 2025, https://www.ars.usda.gov/ARSUserFiles/30180000/DernerPDF/27.PotterandDerner2006.pdf

59. Management Effects on Soil Organic Carbon in Texas Soils - USDA ARS, accessed May 29, 2025, https://www.ars.usda.gov/ARSUserFiles/60100500/csr/ResearchPubs/torbert/torbert_10c.pdf

60. What Can I Do to Limit My Impact on Stormwater Runoff? | Carrboro, NC - Official Website, accessed May 29, 2025, https://www.townofcarrboro.org/2471/What-Can-I-Do-to-Limit-My-Impact-on-Stor

61. louisiana's coastal prairie restoration conservation reserve enhancement program agreement - Farm Service Agency, accessed May 29, 2025, https://www.fsa.usda.gov/Internet/FSA_File/la_crep_draft_032607.pdf

62. dallascityhall.com, accessed May 29, 2025, https://dallascityhall.com/government/Council%20Meeting%20Documents/qol_1_txdot-right-of-way-maintenance_briefing_011116.pdf

63. City Council Development Committee Meeting Agenda - Grand Prairie, accessed May 29, 2025, https://www.gptx.org/files/sharedassets/public/v/3/government/mayor-and-city-council/documents/city-council-development-committee-meeting-agenda-7-21-20.pdf

64. AVERAGE LOW BID UNIT PRICE - MAINTENANCE - LAREDO DISTRICT, accessed May 29, 2025, https://www.txdot.gov/insdtdot/geodist/lrd/cserve/bidpricm/s_0701.htm

65. www.nrem.iastate.edu, accessed May 29, 2025, https://www.nrem.iastate.edu/research/STRIPS/files/publication/the_cost_of_prairie_conservation_strips.pdf

66. Chapter 5: Economics | Science-Based Trials of Rowcrops ..., accessed May 29, 2025, https://www.nrem.iastate.edu/research/STRIPS/chapter-5-economics

67. Cost and Trends of Rx Fire in Southern Forestry Practices - West Texas Rangelands, accessed May 29, 2025, https://agrilife.org/westtexasrangelands/cost-and-trends-of-rx-fire-in-southern-forestry-practices/

68. Texas A&M Forest Service awards $951000 to landowners for prescribed fire, accessed May 29, 2025, https://tfsweb.tamu.edu/texas-am-forest-service-awards-951000-to-landowners-for-prescribed-fire/

69. Is this a reasonable invasive removal quote (for my parents) : r/NativePlantGardening, accessed May 29, 2025, https://www.reddit.com/r/NativePlantGardening/comments/1jddsz0/is_this_a_reasonable_invasive_removal_quote_for/

70. City of Austin Invasive Plant Management Cost Approximate Estimates, accessed May 29, 2025, https://www.austintexas.gov/edims/document.cfm?id=138267

71. Aquatic Invasive Species Management: Summary of Texas Statewide Efforts FY 2022-2023, accessed May 29, 2025, https://tpwd.texas.gov/landwater/water/aquatic-invasives/media/Statewide_AIS_Management_FY22_23.pdf

72. Aquatic Invasive Species Management: Summary of Texas Statewide Efforts FY 2020-2021, accessed May 29, 2025, https://tpwd.texas.gov/landwater/water/aquatic-invasives/media/Statewide%20Aquatic%20Invasive%20Species%20Management%20Efforts%20-%205%20year%20update_WEB.pdf

73. NAISMA Final Appropriations Recommendations Letter 3.22.2021, accessed May 29, 2025, https://naisma.org/wp-content/uploads/2021/08/NAISMA-Final-Appropriations-Recommendations-Letter-3.22.2021.pdf

74. FAQ: What do prairie strips cost? | Science-Based Trials of ..., accessed May 29, 2025, https://www.nrem.iastate.edu/research/STRIPS/content/faq-what-do-prairie-strips-cost

75. Blackland Prairie Mix | Native American Seed, accessed May 29, 2025, https://seedsource.com/blackland-prairie-mix/

76. Blackland Prairie Mix - Nativo Gardens, accessed May 29, 2025, https://www.nativotx.com/products/blackland-prairie-mix

77. Budgeting for Prairie Strips - UNL CMS, accessed May 29, 2025, https://cms.unl.edu/ianr/snr/applied-spatial-ecology-lab/sites/unl.edu.ianr.snr.applied-spatial-ecology-lab/files/media/file/Prairie%20Strips%20Ecological%20Benefit%2011x17%20.pdf

78. Public Works | GIS - Dallas County, accessed May 29, 2025, https://www.dallascounty.org/departments/pubworks/GIS.php

79. Sharrows, Lanes and Velowebs | Irving, TX - Official Website, accessed May 29, 2025, https://www.cityofirving.org/631/Sharrows-Lanes-and-Velowebs