From redevelopment to parking policies to planting trees, stormwater planning meshes with ongoing local efforts.

Cities, counties, towns, and campuses around the country are well into developing stormwater plans as required by the National Pollutant Discharge Elimination System (NPDES) Phase II under the Clean Water Act. At times, the work to be done on outreach, planning, monitoring, and menus of best management practices (BMPs) may seem daunting. In particular, the post-construction rules have added a new dimension to how cities must monitor, control, and track stormwater management over the life of development projects.

What many local water-quality managers and their consultants might not realize is that their colleagues in the transportation, planning, and zoning departments are engaged in planning activities that parallel, and often overlap, watershed and stormwater planning. The cities and counties affected by Phase II also happen to be the fastest growing around the country. States and local governments have adopted growth management and smart-growth legislation for goals that include environmental protection, more efficient use of public investments, and improved quality of life. Embedded in those land-use and comprehensive plans are features at the site, neighborhood, and even regional levels that have a great impact on the quantity and quality of stormwater.

This article looks at several smart-growth techniques and how water-quality managers can take advantage of efforts already under way. You may be able to piggyback Phase II requirements for outreach, education, and post-construction controls onto programs that are already under way—and, in many cases, already funded and staffed.

What Is Smart Growth?

Simply put, smart growth is development that serves the community, the economy, and the environment. According to the Smart Growth Network, there are 10 guiding principles of smart growth:

• Mix land uses
• Take advantage of compact building design
• Create a range of housing opportunities and choices
• Create walkable neighborhoods
• Foster distinctive, attractive communities with a strong sense of place
• Preserve open space, farmland, natural beauty, and critical environmental areas
• Strengthen and direct development toward existing communities
• Provide a variety of transportation choices
• Make development decisions predictable, fair, and cost-effective
• Encourage community and stakeholder collaboration in development decisions 

Although better stormwater management is not explicit in these principles, the water-qualtity benefits are, quite literally, built in. Compact building design, including the building itself as well as parking, reduces the amount of impervious surface associated with a building project. Directing development toward existing communities makes better use of existing infrastructure and provides an economic base for ongoing maintenance and repair of pipes, treatment plants, and conveyance systems. Creating transportation choices lessens the adverse impacts that arise when automobiles are the sole option for transportation.

Cities and counties are adopting a range of policies, financial assistance, and planning techniques to meet smart-growth goals. EPA's model stormwater permit included several smart-growth techniques, in recognition of the water benefits that come with comprehensive approaches in deciding where and how to grow. Thus, many smart-growth strategies are emerging as BMPs for meeting the requirements of Phase II, particularly for the post-construction minimum measure.

Redevelopment Programs and Vacant-Property Policies

Perhaps one of the strongest policies for water quality is the reuse of underused property or vacant buildings. The property is already developed and can absorb development demand that might otherwise be put on undeveloped sites elsewhere in a watershed. Many cities are pursuing redevelopment programs as an economic revitalization strategy, but officials need to recognize the water-quality implications as well. Cities that have established programs to put vacant properties back into use, redevelop brownfields, or sponsor "Main Street" programs should consider these as part of a stormwater strategy.

Don Chen, executive director of Smart Growth America, is also a co-chairman of the National Vacant Properties Campaign. "Replacing a vacant strip mall or warehouse with new housing is the ultimate in conservation design," he observes. Housing built in older parts of cities is also likely to be located near existing retail stores, schools, and services. Joint stormwater and smart-growth planning is an approach to simultaneously consider the site level and the larger regional or watershed level.

Redeveloping already-impervious surfaces also means that a city can actually improve the stormwater handling on a site by fixing older pipes as part of the redevelopment plan or using part of the site to handle stormwater through landscaped areas or green building techniques.

By setting up a system to track how many vacant properties are redeveloped, a city has an automatic way to set up and track "measurable goals." A city or county could set a goal of redeveloping 10% of its abandoned building stock each year.

Urban Forestry Programs

Programs to establish, maintain, and increase trees and tree canopy are becoming a popular element in local plans. Some plans call for street trees in residential and commercial districts, while others aim to save older and historically significant trees. Setting a tree canopy goal for a community helps maximize the ecosystem services trees can provide. The environmental benefits for cleaner air and stormwater management are well established. The stormwater benefits are typically presented in terms of erosion control, or by how much rainfall can be intercepted and stored or released over time. Phase II offers one of the best opportunities for regulatory recognition of those benefits.

New software programs are available to assess how much rainfall can be intercepted by trees. American Forests has developed an urban ecosystem analysis that can track tree canopy, impervious surface, and other land-cover changes over time. The nonprofit association's CITYgreen software calculates the ecosystem services that trees provide for stormwater control as well as for water and air quality. Cheryl Kollin, director of the Urban Forest Center at American Forests, helps people connect the environmental benefits of tree cover with their cost savings to promote better planning and public policy. She delivers technical assistance to cities across the country. "With Phase II's emphasis on measurable goals, programs that can be readily and easily measured will stand out as cities make decisions on stormwater strategies," she notes. "What makes tree programs so beneficial are not only the measurable environmental benefits, but the related cost savings on infrastructure as well."

The City of Roanoke, VA, used CITYgreen to measure cost savings associated with its tree canopy. Roanoke's 32% tree canopy provides 64 million cubic feet in stormwater retention capacity, valued at $128 million (based on construction costs estimated at $2 per cubic foot). The city council passed a 40% tree canopy goal as part of the city's comprehensive plan.

As with other public investments, many cities find sustained funding for tree maintenance to be a constant challenge. Phase II may emerge as a new and creative way to fund tree maintenance as part of a stormwater management program. Cities that establish BMP maintenance programs might be able to tap funding, either through stormwater utilities or other funding streams, for tree care.

Parking Policies

For most communities, any comments on parking will be that there is not enough of it. In reality, though, development projects tend to build too much parking. In the past, excess parking spaces that are rarely used were seen as a development feature that came with little or no extra cost. However, the costs are becoming more apparent as localized flooding increases, infiltration is diminished for aquifer recharge, and local water quality decreases. For stormwater managers, this extra impervious surface presents a real challenge, but one that can be tackled by reviewing and fine-tuning development regulations.

Local governments and developers typically plan the number of spaces for a particular development project based on published standards. These standards suggest a given number of spaces per thousand square feet or per housing unit and tend to overestimate the number of spaces needed. EPA's menu of BMPs for post-construction stormwater management presents a section on parking and an analysis of how many spaces tend to get built compared to typical demand for a variety of uses. For example, the recommended parking ratio for shopping malls is five spaces per thousand square feet, and the typical range of spaces provided at shopping malls tends to be anywhere from four to six spaces. However, the actual demand is typically four spaces per 1,000 square feet. For more on background on "green parking" in EPA's BMP menu, see http://cfpub.epa.gov/npdes/stormwater/menuofbmps/post_12.cfm

Communities can adopt several policies to better manage parking and, hence, the stormwater that flows through lots. These can include:

• Shared parking arrangements among several building owners or tenants. Different types of businesses can have different demand for parking throughout a day. For example, spaces used by office workers during the day can be used for restaurant parking at night. Shared arrangements usually are based on an agreement signed by the users so that liability, patrol, and cleanup are agreed on ahead of time.
• Better use of on-street public parking spaces. Parking along public streets might be an overlooked resource for a community that wants to add parking efficiently. Unused travel lanes can be converted to spaces, or parallel parking spaces can be converted to diagonal spaces to add parking. In St. Louis, diagonal parking is allowed on Sunday near churches on spaces otherwise used for parallel parking during the workweek.
• Setting parking maximums, not minimums. Parking standards are usually expressed as the minimum number of spaces to consider for a particular use (e.g., retail or housing). Parking maximums put a cap on the number of spaces that can be built and gives water managers better control on the overall development footprint of building projects.
• "Unbundling" the cost of parking for apartments. Renters usually write one check a month for rent, which includes the cost of a parking space. By "unbundling" the cost of the parking into a separate bill, the real costs of a parking space are accentuated. Unbundling the costs of parking can be a good strategy to argue for fewer spaces where land costs are high and where other transportation options exist. This can also be a good strategy in college towns where parking pressures are severe and the potential for new or expanded transit is high.

By reducing local standards for how much parking is built, cities can track how much less land is devoted to impervious surfaces. A city can compare how much parking is actually built under improved standards and compare the results with how much would have been built according to the older standards that allowed more spaces.

Low-Impact Development and Conservation Subdivisions

Low-Impact Development, or LID, mainly has its roots in residential subdivision design. However, there are many more applications that can be used in a number of development settings, including ultra-urban ones. The goal of LID is to mimic the natural hydrology of a site. In rural and suburban settings, this can mean a site layout that avoids low-lying areas and leaves forests and habitat corridors intact.

In urban areas, the natural hydrology likely has been severely disrupted. However, communities can look at restoration techniques including multiuse parks, stream improvement, and rain gardens. Individual building projects can include landscaped areas and green building techniques that result in buildings with lower environmental impacts.

Conservation subdivision design is increasingly showing up in manuals as a BMP. As noted above, conservation subdivisions, or clustered housing, increase the density of housing on part of a site while leaving the rest of the larger plot of land untouched for both aesthetic and environmental reasons. Traditionally—and often mistakenly—density has been associated with a loss of water quality. However, on a per-unit basis for housing, the amount of land consumed, and the associated impervious surfaces for transportation and infrastructure to serve that housing unit, are far less than for conventionally platted subdivisions. Increasing density in preferred growth areas not only reduces the development footprint but also can result in communities that are more walkable and amenable to a variety of uses. By increasing the development intensity in designated areas, there is less pressure to spread outward into the watershed.

A spirited debate is emerging as to whether conservation subdivisions are environmentally preferable, or whether they merely introduce development into areas that are not slated for growth. The details of the debate are still being worked out, although water managers and land-use planners alike should recognize that conservation subdivisions and clustered housing have a role to play in promoting better development practices. For example, Ottawa County, MI, promotes conservation design as part of a comprehensive plan to support its agricultural economy. The county wants to attract new workers for its growing agricultural sector, and these new workers will need housing. The county has developed an entire suite of rural planning tools so that housing is considered in conjunction with other development goals. To read more on Ottawa County's programs, see http://www.co.ottawa.mi.us/PlanningGrants/OCPG.htm.

Outreach and Education

Aside from meeting the needs of post-construction requirements under Phase II, local governments should also look to their smart-growth programs to conduct the outreach and education components of Phase II. Community outreach is a standard part of developing comprehensive plans. By adding a stormwater component to local planning efforts, a community can fulfill its outreach commitments while developing a program that addresses land and water needs at the same time.

More Information

EPA and other organizations are developing a growing number of Web sites and publications to help communities develop plans and policies that consider both smart growth and stormwater. EPA's Web site on smart growth (www.epa.gov/smartgrowth) contains links to many free publications, some of which are listed below. If you are new to the subject of smart growth, a good starting point is "Why Smart Growth—a Primer." For communities looking for specific policies and implementation strategies, two primers—"Getting to Smart Growth" and "Getting to Smart Growth II"—offer information, examples, and additional resources. EPA also recently published "Protecting Water Resources with Smart Growth." EPA's Office of Water sponsors the Watershed Academy, which contains educational materials that can be downloaded for free. See http://www.epa.gov/owow/watershed/wacademy/. For other materials on smart growth, see the Smart Growth Network's Web site at www.smartgrowth.org.

Guest editor Lisa Nisenson works in EPA's Office of Policy, Economics, and Innovation.

SW November/December 2004