Watershed, Stormwater, & Integrated Water Management
- Charles River Basin MS4
the challenge According to the 1996 National Water Quality Inventory, urban stormwater runoff is a leading source of water pollution. The under NPDES Phase II of the Clean Water Act, the Stormwater Program for Municipal Separate Sewer Systems (MS4s) is designed to reduce the amount of sediment and pollution that enters surface and ground water from storm sewer systems. A regionally active non-profit advocacy group, the Conservation Law Foundation (CLF), engaged the Bioengineering Group to review the permit applications of three Massachusetts municipalities to assess their compliance with the regulations and their potential for achieving the required water quality objectives.
the interdisciplinary approach We first defined the critical issues important to the protection of water quality. Since stormwater runoff can change natural hydrologic patterns, accelerate stream instability, destroy aquatic habitats, and elevate pollutant loadings, our review focused on the proposed programs for source control. Source control that replicates the natural hydrologic cycle is one of the most effective strategies for dealing with urban runoff, a practice known as Site Scale Sustainable Hydrology. By collecting and infiltrating precipitation as near to where it falls as possible, runoff is reduced, groundwater is recharged, and pollutants are removed through physical, biological and chemical processes in the soil and vegetation. The MS4 regulations require the permittee to identify best management practices (BMPs) and measurable goals associated with each minimum control method. We reviewed the source control strategies in each permit application looking not only for effective measures for elimination of illicit connections, but for procedures to review permits for new development to ensure that appropriate BMPs were employed and that programs were in place to inspect and maintain such BMPs. Other factors reviewed included whether programs addressed existing problems with flashy hydrology and unstable streams that contribute to excessive sediment transport, the and the presence of programs to engage and educate the public in the importance of sound watershed management.
the resultsThe Bioengineering Group reported our recommendations to CLF for incorporation during the comment period for the draft plans. Those comments were, reviewed by the municipalities who then adjusted their programs (including local ordinances and maintenance practices) to address the identified deficiencies, which in turn will leverage further improvements. This process resulted in improved programs with measurable outcomes that together and over time will do much to improve the water quality of the Charles River Basin, based not only technical process, but on an effective strategy of establishing water quality goals and crafting the context sensitive programs to best achieve the targeted results.