Applying Offsets for Cost-Effective Stormwater Management

Stormwater management is experiencing a paradigm shift. This shift involves an increased focus on reducing the environmental impacts as sociated with stormwater runoff. However, treating stormwater to reduce pollutant loading is expensive and the costs tend to be highly variable. A cost-effectiveness analysis enables managers to select treatment practices that will provide the maximum reductions for the least cost. In addition, allowing stormwater entities to apply offsets toward pollution reduction requirements can accelerate water quality improvements.Existing offset programs provide a model for cost-effectively reducing pollutant loads from stormwater runoff. Offsets helped Western Michigan University in Kalamazoo, Michigan surpass its phosphorus load reduction goal. An offset program being developed for Lake Simcoe in Ontario, Canada will help reduce phosphorus loads associated with urban development. These programs, as well as efforts in Virginia, Washington, D.C., and Lake Tahoe, demonstrate the role of offsets as a flexible, cost-effective option for stormwater management.