Regional and farm-level analyses are conducted to evaluate the economic and environmental impacts of water quality protection policies. The regional analysis evaluates reducing nitrate losses by reducing per-acre nitrogen use, taxing nitrogen use, taxing irrigation water use, and reducing furrow irrigation. Incentives to convert furrow systems to sprinkler and LEPA systems outperform the other policies. The firm-level analysis derives farm plans that limit the expected values of environmental indices for nitrates and pesticides, and reduce the probability that specified targets will be exceeded. The analysis demonstrates the importance of evaluating environmental risk as stochastic process.