Ecosystem Services Modeling to Achieve Sediment and Phosphorus TMDL Goals for Lake Pepin, MN.

A full-cost-accounting framework was used to evaluate alternative methods of achieving watershed load reductions of sediment and phosphorus required by the Lake Pepin TMDL. Two types of models were used in three small Minnesota watersheds to evaluate how different spatial allocations in the watershed of practices such as conservation tillage, nutrient management practices, riparian buffers, cover crops, wetland restoration, or perennial energy crop plantings could be used to reduce phosphorus and sediment losses to surface waters draining to Lake Pepin.   Modeling approaches were based on the use of the Soil and Water Assessment Tool (SWAT) and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) models.  SWAT was used to estimate water quality impacts of various spatial configurations (location and area) for each conservation practice.  InVEST was used to predict ecosystem services associated with emissions of greenhouse gases, carbon sequestration, and spatial extent and quality of bird habitat.  SWAT estimates of crop yields and biofuel production were passed to InVEST in order to estimate market values associated with gain or loss of cropland in each conservation scenario.  Economic and ecologic tradeoffs associated with each scenario are described in a manner that can be used by policy-makers to inform conservation choices used to attain TMDL goals.