Guest Editorial: Towards a National Stormwater Criteria

Nature-based, sustainable, and resilient with community benefits beyond stormwater

A stream buffer in west Austin
A stream buffer in west Austin
Tom Hegemier

Our country is large in area and diverse in nature and covers many ecoregions with many weather patterns. From deserts to swamps, from the mountain tops to the lowlands, from less than 10 inches to more than 60 inches of rainfall per year, Americans live in vastly different ecosystems. Considering these differences, what should each community ask of their stormwater criteria? From my observations, stormwater practices should be implemented in a similar manner across our nation, with the goals being to protect streams, rivers, and lakes from degradation; preserve natural habitat to maximize ecosystem services; maintain environmental integrity; minimize flood risk; manage water withdrawals from aquifers, rivers, and lakes; and encourage stormwater reuse for beneficial purposes.

In other words, we are more alike than we are different. While water scarcity is a big issue in the west and efficiently managing large water volumes in the east can be challenging, the common thread of a stormwater criteria can be summed up to protect the natural character of our receiving waterways. If we can do that, then all other goals can be addressed through the stitching of regionally appropriate hydrologic criteria and measures into the fabric of local stormwater criteria. This can flow from a national criteria that sets the building blocks for local jurisdictions to adopt and modify so that we have equitable stormwater practices that most importantly protect our water resources and oceans. That’s right, oceans—they have the incredible power to inflict great damage and loss of life, as we experienced in Hurricanes Sandy and Harvey, to name just two. Yet the oceans of the world continue to accumulate massive amounts of plastic and floatables each year from our cities and rivers.

In my company’s effort drafting the Texas coastal nonpoint source (NPS) program plan to seek federal approval, we found that the Coastal Zone Act Reauthorization Amendments (CZARA) management measures drafted by EPA in the early ’90s layout a well-thought-out guidance. We extracted the key measures to develop a model ordinance/criterion that is concise and simple to implement. The guidance incentivizes green infrastructure, low impact development, and multi-purpose facilities to meet the region’s stormwater goals in an affordable manner. The goal is for local jurisdictions to adopt and implement these basic tools and criteria. Yet, the measures for the Texas Coast can be applied to the mountain west with a few slight modifications for their hydrologic conditions. We found six major measures for stormwater management.

Construction Site Runoff can dramatically impact stream geomorphology, aquatic habitat, stream health, and species. Many view construction runoff as the most serious water quality threat, as it can foul waters with excessive turbidity, smother habitat, and, in areas of high deposition, increase flooding and divert flows generating impacts to roads, homes, and infrastructure. Construction runoff sediment loads can be 1000 times higher than land in an undeveloped state. Cleanups can run into the millions of dollars and often it doesn’t happen due to lack of enforcement and funds. The key to successful erosion control is a regulatory jurisdiction that has experienced staff who require comprehensive erosion control plans that adapt with the changing construction site. Most importantly, the jurisdiction staff must verify that the field execution is timely and properly performed as the construction phases play out. They must also be willing, able, and supported by elected officials to take enforcement action and require cleanups in the event of sediment discharges.

An extended detention basin in central TexasAn extended detention basin in central Texas

Stream Buffers are the sharpest tool in the stormwater toolbox. The nation’s rivers and lakes originate from a network of small and headwater streams that are known to significantly influence the quantity and quality of downstream waters. We know that headwater streams make up at least 80% of the nation’s stream network. In addition to water quality benefits, these small streams mitigate flooding, generate local recharge, recycle nutrients, provide habitat for plants and animals, and sustain the biological diversity of rivers, lakes, and estuaries.

Stream buffers, beginning at drainage areas of five acres, are a low impact development (LID) approach to ensure that land use change and drainage practices do not occur in the natural waterways. In Central Texas, stream buffers have been part of the regulatory requirements by the City of Austin and other jurisdictions since the 1980s to protect surface and groundwater supplies.

Stream buffers provide every-day ecosystem service benefits when compared to constructed stormwater practices that only function during rainfall/runoff events. They also generate recreation and trail opportunities to connect communities to their local waterways and serve as a recreation amenity that can bring children to the water. See education below.

A creek in a natural state.A creek in a natural state.

Stream Protection Volume and Water Quality Treatment work hand-in-hand to protect streams from the hydrologic and water quality impacts of urbanization. Urbanization’s impact on hydrology, rate, volume, and frequency can increase the depth and width by a more than a factor of five, essentially eliminating the natural resource and threaten public infrastructure, homes, and property.

Volume control for 24 to 48 hours has been shown both in studies and in the field to minimize channel degradation in urbanizing watersheds. It is a design approach that ends hydrologic gamesmanship in the peak to peak design analysis. For more on this, see “Voodoo Hydrology,” published in Stormwater July/August 2006.

The same creek, just downstream of the previous photo, but lined with concrete.The same creek, just downstream of the previous photo, but lined with concrete.

Instead of requiring complicated water quality models that most land development engineers are not familiar with, a simple design spreadsheet tool can compute the runoff volume for the 85 to 90 percentile storm that is managed through extended detention. Extended detention basins can manage from 75% to nearly 90% of the total suspended solids load according to the Texas Edwards Aquifer Protection Program. The EPA has identified that sediment is the leading cause of impairment in urban areas with road sources listed as the most detrimental to the aquatic system and includes vehicle and exhaust emissions, vehicle and tire wear, road salts and paints, brake lining material, and high concentrations of metals.

With the focus on suspended solids and the knowledge that stream buffers will provide polishing treatment, we can rely on extended detention to manage urban runoff rather than chasing high removal rates of dissolved constituents that leads to costly and difficult to maintain systems. It will be difficult to convince a community to initiate a watershed protection ordinance that requires high-cost systems and the corresponding long-term maintenance expenses.

We are implementing techniques to draw water off the top of the extended detention pool through the use of a J. W. Faircloth skimmer and the smartBatch Detention system from Eco Construction Services to further improve runoff quality. At the Lower Colorado River Authority in central Texas, we developed an enhanced extended detention system that includes down-gradient vegetated filter strips and infiltration trenches. We can design stream protection/water quality volume to be distributed around the site development in rain gardens, rainwater harvesting, previous pavement, conservation landscaping, disconnected runoff, bioswales, and natural area protection that can generate water supply benefits in the drier west. In other words, a green infrastructure plan.

Table 1. Six Key Measures for Stormwater CriteriaTable 1. Six Key Measures for Stormwater Criteria

Flood Risk Management has been practiced for decades across the US and continues to be an important requirement to manage urban runoff to protect downstream residents. The advantage of extended detention for water quality and stream protection is that it can also provide flood detention in the same facility. Flood management should be designed per the hydrologic conditions in each region and use the available hydrologic and hydraulic tools to size storage and outflow structures. Stormwater basins should also function as recreational amenities to gain further general public and elected official acceptance. The Urban Land Institute recommends that everyone should be within a 10-minute walk to a park and smartly designed stormwater basins can provide the recreational space in the urban environment

Water Quality Education Materials should be a permit condition and shared with new residents and commercial operators so that they are aware of their local water resources and the actions that they take can help protect water quality and aquatic habitat. The materials can be provided at move-in to new residents to guide the proper use and storage of fertilizer, herbicides, pesticides, and chemicals. A customized document for commercial and industrial operations is also necessary. The local stormwater authority through their MS4 permit or other tools should be active in sharing brochures, web posts, and event information. It’s important that the residents know that the creeks their children play in are safe and healthy and educating children about water quality and stormwater can create life-long water stewards.

Stormwater Maintenance is a must to ensure that the stream buffers are protected and stormwater basins are properly installed and maintained in perpetuity. The local stormwater jurisdiction must have proper funding to ensure that maintenance happens. Typically, water utilities are better funded than stormwater agencies and they receive the benefits of clean and managed stormwater. If possible, water utilities should help fund stormwater agencies as the benefits of cleaner and recharged runoff can reduce treatment costs and help the utility defer long-term water supply development costs. It comes down to the local watershed—if we create healthy watersheds, we will have healthy cities.

We have national standards for water and wastewater treatment, and now is the time to consider the same for stormwater management. Keep stormwater management simple so it can be accepted and adopted by local jurisdictions and become a standard part of the development process. Our nation’s waterways and oceans will reap the rewards, aquatic habitats can thrive, and future generations will be able to enjoy our rivers, lakes, and beaches. 

References
Barret, Michael, Tom Hegemier, and The Meadows Center for Water and the Environment at Texas State. Guidance for Sustainable Stormwater Drainage on the Texas Coast: For Nonpoint Source Pollution and Flood Management. 2nd ed. June 2019.

George, Patrick. “Hays County gets $425,000 in Hamilton Pool Lawsuit,” Austin American-Statesman, September 1, 2012. www.statesman.com/article/20120901/NEWS/309004238.

Hegemier, Tom. “Are We Aiming at the Right Stormwater Management Target?” Stormwater July/August 2015, 10–11. www.stormh2o.com/home/article/13018547/guest-editorial-are-we-aiming-at-the-right-stormwater-management-target.

Hegemier, Tom. “Stream Buffers.” Stormwater January/February 2017, 16–25. www.stormh2o.com/home/article/13027970/stream-buffers.

Lower Colorado River Authority. “Permanent Water Quality Treatment Best Management Practices.”Highland Lakes Watershed Ordinance: Water Quality Management Technical Manual, 4-1–4-80.

Reese, Andrew. “Voodoo Hydrology.” Stormwater July/August 2006, 42–78. www.stormh2o.com/home/article/13003575/voodoo-hydrology.

Urban Land Institute Center for Sustainability and Economic Performance. “10-Minute Walk Campaign.” www.americas.uli.org/research/centers-initiatives/10-minute-walk-campaign/.

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