Integrate smart growth into the State's stormwater program
Action
The federal Clean Water Act directs states to implement stormwater management programs to reduce erosion and floods from runoff. Stormwater washes pollutants from roads, parking lots and other hard surfaces into streamsand other bodies of water. As more land is converted to impervious surfaces or when agricultural lands are not properly buffered with trees, stormwater runs off faster causing erosion, sedimentation contamination and, in some cases, flooding.
Stormwater is best understood at the site level, where conventional drainage practices basically divert runoff to the nearest waterway. The cumulative impact of connected drainage has been detrimental to streams, because collected pollutants, excess volume, and fast-flowing water have altered habitat, water quality, and floodplains. At the larger watershed scale, land alteration, grading and loss of natural cover affect aquifer recharge, stream flows and floodplain management. Many state costs related to property damage, inter-basin water transfers and regional detention can be traced back to poor development practices.
State stormwater programs and permits can provide less expensive, more effective, and more flexible alternatives for communities when they take into account the role that more sustainable development practices can play in achieving clean water. In October 2008, the National Academy of Sciences released a report urging transition from the current permitting structure to one that is watershed based. This approach would look at broad land conservation and green infrastructure as a first step in managing water resources, including stormwater. For new development, requirements would be shaped by their location in the watershed but at a minimum would emphasize low-impact techniques. Infill and redevelopment come with very different stormwater needs, in part because brownfields and other redevelopmentsites require carefully selected combinations of best management practices to address urban pollutants and to overcome site constraints.
Process
The program elements that states administer for stormwater programs include: 1) the permit, 2) lists of accepted practices and performance standards, 3) guidance or design manuals, and 4) outreach and education materials.
States can rewrite their stormwater permits and associated manuals to recognize the effectiveness of smart growthapproaches in preventing and reducing stormwater runoff. Depending on the existing environmental and economic conditions, this may include:
- separating the National Pollutant Discharge Elimination System (NPDES) and program elements for new development, redevelopment and infill;
- establishing a credit system to account for "imperviousness avoided" through redevelopment, compact development and/or vertical development; and
- developing stormwater projects, through an economic development fund, tied to NPDES compliance as an incentive within identified growth and redevelopment areas.
For example, states can provide a methodology for determining the how much runoff could be avoiding by reusing a brownfield site versus thesame level of development as built under conventional zoning on a greenfield site. Such an type analysis would move away from conventional engineering assessments that only consider runoff from individual sites, to a more robust evaluation of watershed-level impacts, improvements and tradeoffs.
Brownfield redevelopment reveals a level of stormwater planning that is often overlooked: planning at the district level. Most permits require either large-scale watershed planning or detailed site design.. One of the most powerful tools for shrinking the environmental impacts of new development and redevelopment, however, involves coordinating development within a district. The coordination can result in shared impervious cover (such as parking and loading areas), support for higher density and mixed-use development, and low-impact transportation choices. The stormwater benefits are likely to include advanced planning to control runoff within the district and a smaller overall development footprint.
In addition to watershed plans and low impact site design, states can develop permits, performance standards, and design manuals for districts. In fact, states may have prepared the groundwork in manuals directing transit-oriented development, traditional neighborhood design or downtown redevelopment.
Examples
- California’s Regional Water Quality Control Boards
California has divided the state into nine Regional Water Quality Control Boards to address differences in rainfall, flooding and restoration. The Los Angeles Regional Water Quality Control Board has issued draft permits with innovative approaches to district-level stormwater management. The draft Ventura County permit establishes a "Redevelopment Plan Area Management Plan," which can serve to control stormwater runoff from the developed area. The premise of such a district is that the rigorous performance standards established for individual developments may not be feasible in areas struggling to attract investment or may encourage building rehabilitation instead of redevelopment to circumvent permit requirements. By pursuing both site improvements and district-wide approaches, cities have expanded options to leverage capital investment, economic development funds and shared solutions to stormwater runoff management. Several cities in Ventura County are exploring use of this, or some similar approach, to control stormwater.
— California State Resources Control Board - Michigan’s Water Program
The State of Michigan is recognized as a national leader in flexible and innovative water programs, including the Rouge River demonstration project and the alternative watershed-based stormwater permit. Michigan has worked closely with towns wishing to pursue innovative use of permitting flexibility. One of the more recent examples involves Grand Rapids.In seeking to direct growth downtown, the city formulated a credit system for high-density development in its core. The system compares the footprint and runoff of a multistory building to the footprint of the same amount of development if constructed under conventional zoning. For example, a five-story building with 20 apartments would produce far less runoff than would 20 single-story, single-family homes with their additional rooftops, driveways and road networks.The city also determined that the receiving body of water could accept the runoff from previously developed areas since the buildings were replacing impervious cover.
— Presentation on Grand Rapids’ program
