Water at the Grass Roots
by Wendy Grey, AICP
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Several other articles in this issue of Quality Cities address federal mandates, state policies and intergovernmental cooperation regarding water resources. In this article, we will take a look at water resources from the perspective of cities. Since water does not respect jurisdictional lines, it is logical that various levels of government have a responsibility to address the protection of water resources. Nevertheless, for all the regional, state and federal interest in water issues, local governments are the true stewards of water. Development and landscaping practices and stormwater treatment regulations are the first level of water-resource management. In this article, we will take a look at a local water-management approach called low impact development, or LID. LID literally takes a grassroots approach to water protection. It is becoming popular in many cities around the country.
Background
Prince George’s County, Md., is credited with starting the LID movement in the mid-1980s. LID principles now are being studied and applied nationally.
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What is LID? LID is based on the following principles:
- Stormwater management isn’t just about flooding and water quality. Stormwater actually begins as rainfall, which is a resource critical to our quality of life. In nature, rainwater provides us with drinking water and preserves habitat. LID design seeks to replicate all those benefits of rainfall, using the same principles that are found in nature.
- LID is about treating stormwater closest to the area where it falls. If the application of LID techniques is successful, a developed site will have many of the hydrological characteristics that it did before it was developed. For example, much of the rainwater will be retained on site; it will filter into the ground and support native vegetation.
- LID is site-specific. Since LID is based on the concept of treating stormwater close to where it falls, there is no one-size-fits-all design. Since each site is different – the vegetation, the soils, the topography – and since the proposed use of a site will vary (a shopping center or subdivision, for example) – the range of tools that are used must be tailored to each site.
The tools of LID are varied. They may include swales or other types of depression, specially designed landscapes, or pervious paving materials. The literature even includes a review of grassed roofs!
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LID vs. Conventional Stormwater Management
How does LID compare with conventional stormwater management? You probably already have identified a number of differences. For one thing, conventional stormwater management is based on a highly centralized approach. From a pond on an individual site, water is conveyed through a series of pipes or ditches to another location, where it may receive additional treatment, and is eventually discharged. This centralized system tends to result in dramatic volumes of water being pushed through the system during heavy storms. LID seeks to mitigate the extreme flooding peaks the way nature does – by providing more opportunities for the water to stay close to where it falls.
Another difference is cost. Conventional systems are expensive to build and maintain. Land acquisition for ponds and conveyances grows as land becomes more expensive. Although research still is being conducted, there is evidence that LID systems are less expensive to build and maintain.
Since LID is decentralized, it can put more responsibility on the property manager or owner, versus a stormwater authority. LID is intended to be low maintenance, but it is not no maintenance. However, LID facilities, generally composed of small ponds and landscaped areas, may be easier and more desirable for people to maintain than conventional facilities.
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Rain Gardens: A Neighborhood Approach to LID
LID techniques can be used in development of any scale. In fact, an article on the Environmental Protection Agency Web site referenced a study of the Florida Aquarium parking lot in Tampa, showing how pervious pavement was more effective than cement or asphalt in reducing pollutants.
There is a small-scale application of LID that may be a good way for your city to experiment with this new technique: rain gardens. Rain gardens are not much more than a small depression, pond or swale integrated into a residential yard. The area is planted with native vegetation. It is intended to catch the water from roofs and driveways, and keep it from running off. The rain garden also treats the rainwater before allowing it to soak back into the soil.
On first glance, this may not sound like a very practical technique – fixing one yard at a time. But think about the many subdivisions in your city that were developed before stormwater regulations were in place. There may be hundreds or thousands of homes whose roofs, patios and driveways create a tremendous amount of runoff. Or think about infill development in older subdivisions, where flooding suddenly becomes a problem for downstream neighbors. If each house in one of these subdivisions treats the water that lands on its lot, the cumulative effect in terms of flooding and water quality can be significant. I have heard the concept of rain gardens compared to recycling. If one family recycles, there is no effect. When a whole neighborhood recycles, things get noticeably different.
The Ochlockonee Soil and Water Conservation District is implementing a residential rain garden program in Leon County and Tallahassee. Master gardeners and others are working with neighborhood associations to spread the word. Local businesses also are involved. The program’s Web site is referenced on below.
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Conclusion
Water is a vitally precious resource. These days, the approach to stormwater seems to think “out of sight, out of mind.” Whether your city is interested in a whole range of LID approaches, or wants to start with rain gardens, the basic premise of LID is worth considering. Stop thinking of stormwater as a “waste product” to be disposed of, and start thinking about the importance of rainwater to the sustenance of your city. Then consider the range of techniques that can bring the magic of water back into the heart of your city.
Web References
Wendy Grey, AICP, is a planning and land-use consultant. Previously she was director of the Tallahassee-Leon County Planning Department for 10 years and worked for the Florida Department of Community Affairs. For the Florida League of Cities, Grey provides educational programs on planning and growth management to League members and analyzes the impact of proposed planning legislation on cities. For more information, she may be contacted by phone at (850) 566-0155, or via e-mail.
Reprinted from Quality Cities January/February 2005
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