Balancing Wetland Regulation with Stormwater Management on a Watershed-Wide Basis: A Case Study.
Maryland reconciles rapid growth, water-quality goals, and habitat protection.
In response to increasing regulatory authority over its water resources, the Maryland Department of the Environment (MDE) has combined various programs and processes into a 'one-stop shop' where various issues can be addressed in a uniform and consistent manner. As part of this process, onsite conditions are assessed, potential primary and secondary impacts are identified, and mitigative practices are proposed sufficient to offset habitat loss and comply with water-quality standards. This is an effective approach when large-scale, complex projects are submitted for applicable wetland and waterway permits.
Experience has shown that balancing growth and transportation needs with resource and water-quality protection can also involve balancing various approaches within this process to achieve this goal. Specifically, avoidance and minimization requirements of wetland/stream protection programs might not necessarily be compatible with more traditional stormwater management (SWM) strategies. Further, MDE's process may necessitate the consideration of requirements and practices that can exceed those required by the local municipality.
Presently, MDE regulates activities that may affect or impact water resources and features under the applicable regulations:
- Nontidal Wetlands: areas that are jurisdictional per 1987 US Army Corps of Engineers' Manual and their 7.6-meter (25.0-foot) buffer
- Tidal Wetlands: tidally influenced open ('navigable') waters and their wetlands
- Construction on Nontidal Waters and Floodplains: activities that can alter flow, current, or cross-section of streams and the 100-year floodplain
- Water-Quality Certification: Clean Water Act (CWA) Section 401 review of activity requiring federal authorization (e.g., Corps Section 404 permit)
Most federally regulated projects qualify for the corps Baltimore District's atate programmatic general permit that, in effect, allows MDE to authorize many projects on the corps' behalf.
Piney Branch Watershed
The development project discussed in this article is the first exampleóand therefore yields the most monitoring results—of several subsequent ones in a 405-hectare (1,000-acre) watershed, known as Piney Branch, in Montgomery County in the Greater Washington, DC, metropolitan area. This development is actually one of the first low-impact development approaches to water-quality management before the strategy was formalized in the industry. The initial project, submitted in 1989, proposed stream and wetland impacts for road construction and SWM ponds that were determined by MDE to be avoidable. Impacts were reduced and mitigated by design revisions and innovative approaches to wetland re-creation and SWM while accommodating the demands of a rapidly growing region. Subsequent development projects in this watershed are currently expanding in a manner that utilizes and refines data obtained from this initial project with completion expected by 2004. The positive outcome of this process is attributable to the following factors:
- An effective partnering of engineering and ecology
- Innovative best management practices (BMPs) and SWM strategies that will preserve more riparian habitat and minimize the violation of water-quality standards (especially temperature)
- A site-specific water-quality/stream-biomonitoring plan for the affected watershed to monitor BMP performance and develop state and county initiatives to coordinate future regulatory decisions
- A proactive and cooperative 'win-win' public involvement process, including the property owners
The area lies in the Potomac River watershed between the Mid-Atlantic Piedmont region and the coastal plain. Soils are Glenelg-Manor associations and well drained, silty, and micaceous with occasional subsurface rock. Predevelopment land use was approximately 31% agricultural, 43% woodland, 9% residential, and 17% commercial (includes a crushed stone quarry). Some near-pristine areas remain in the lower reaches of the watershed. Woodlands are primarily deciduous hardwood forest, some of it being regenerative from previous clearing. The remainder was actively cropped field and shrubby intermittently cleared areas. Higher-quality wetland habitat occurred downstream of impact areas.