Based on the dramatic price differentials among sectors for nutrient mitigation options, water quality trading has emerged as a market-based mechanism for cost-effectively meeting water quality goals and the TMDL in three states - Pennsylvania, Virginia and Maryland. Furthermore, given that there are no load allocations for future growth under the Chesapeake Bay TMDL, there is the risk of stifling development without flexible mechanisms in place for handling growth. Trading is considered to be a critical mechanism for accommodating growth through acquiring pollution offsets.