Pollutant Load Reductions for Total Maximum Daily Loads for Highways

Abstract

Increasingly, state departments of transportation (DOTs) are being required to meet water quality goals for stormwater runoff from their highway assets. These goals are characterized as “Total Maximum Daily Loads” (TMDL) by the U.S. Environmental Protection Agency. TMDL is a calculation of the maximum amount of a pollutant that a waterbody can receive and still safely meet water quality standards. To meet TMDL goals, the DOTs must often employ best management practices (BMPs) for mitigating the impacts of stormwater pollutants. This report presents information on the types of structural and non-structural BMPs currently being used by DOTs for meeting TMDL water quality goals for stormwater runoff. The study approach includes two major components: interviews with 12 state DOTs to identify the existing state of the practice as it relates to TMDL implementation, and a review of selected literature sources. Detailed quantitative BMP performance and cost data, including life-cycle costs, are presented.