As the number of impaired waters in New England, continue to climb the region is experiencing unprecedented losses of undeveloped lands. Recent research indicates that we are losing about 33 square miles of forest to development per year in New England and the greatest threat to forest (a land cover that can support aquatic and terrestrial ecosystems) is proximity to developed areas. An analysis of the Narragansett Bay Estuary concluded that protecting undeveloped lands would be one of the best ways to protect the Bay and its ecosystems from further degradation and only a small proportion of the remaining undeveloped lands were protected. Stormwater-quality simulations done by using the Stochastic Empirical Loading and Dilution Model (SELDM) developed by the U.S. Geological Survey in cooperation with the Federal Highway Administration indicates that traditional end-of-pipe treatment of highway and developed-area runoff cannot fully mitigate receiving-water quality issues. Developed-area pollutant yields are about an order of magnitude greater than yields from forested basins, even when stormwater treatment is universal. Stormwater treatment has little if any effect on downstream water-quality at individual sites and cannot achieve water-quality standards in the receiving waters downstream of developed areas, even if implemented basin-wide. Installing each structural stormwater control unit incurs perpetual costs for maintenance and replacement. For example, a recent National Cooperative Research Program study found that the long-term life-cycle costs for removing a pound of sediment, phosphorus, or copper by using conventional stormwater (BMPs) were, on average, about $9, $5, 100, or $38,500, respectively. When such costs are applied to runoff-constituent loads across large areas, the total annualized costs of end-of-pipe treatment could be hundreds of millions of dollars per year. State DOTs nationwide need scientifically defensible information to inform management decisions to go from an end-of-pipe to a watershed-based approach to stormwater management. A program of land conservation coupled with a strategy to use structural BMPs to maintain or extend high-quality stream reaches may help slow the growth in the number of impaired reaches. In some States, DOTs have used the watershed approach to improve receiving-water quality without incurring long-term financial liability for maintaining structural BMPs on site. Offsite mitigation strategies that include in-lieu fees to put forests into land conservation may help preserve stormwater quality and ecosystems in such areas without incurring a permanent BMP maintenance liability. While structural end-of-pipe stormwater BMPs have questionable cost-benefit ratios, it is widely accepted that forests produce millions of dollars per year of benefits including maintenance of air quality, flood reduction, water quality, terrestrial, riparian, and aquatic habitat, reduced climate change, and many economic benefits from recreation. However, quantitative scientific information is needed to support a shift from treatment to conservation