Using a watershed nutrient dynamics model, WEND, to address watershed-scale nutrient management challenges

Nutrient management has become a major focus for watershed-scale planning t o sustain or improve groundwater quality in certain areas. The USDA Natural Resources Conservation Service (NRCS) Watershed Science Institute (WSSI), in cooperation with a number Of partners, is developing a process for creat ing unique, watershed-scale models to examine dynamic phosphorus (P) flows into, out of; and within watersheds using a mass balance approach. The Wate rshed Ecosystem Nutrient Dynamics (WEND) model tracks watershed P balances over time within each of the several land-use sectors. Long-term impacts of various strategic policy decisions on P cycling both within and export fro m watersheds can be modeled The Winooski River Watershed in Vermont is a ca se watershed in which WEND has been used to evaluate the impacts of long-te rm strategies an nutrient use efficiency. The objective of this study was t o describe the effects of three scenarios (status quo, increased rate of de velopment, and increased conservation policies) an P cycling. The model sho wed increased water quality impairment over 80 years under the status quo a nd development scenarios. Under the conservation scenario, P movement into the drainage network was significantly reduced. This suggests that the WEND model could be adopted as an NRCS tool for improved watershed-scale P mana gement.