A mail survey was conducted in Minnesota in 1997 to estimate the value of reducing phosphorus levels in the Minnesota River by 40%. The general population survey of river basin residents was designed to gather information about respondents' use of the Minnesota River in addition to their valuation of a hypothetical water quality improvement program. An estimate of the value of a specific recreational site along the River, the Minnesota Valley National Wildlife Refuge, was also obtained. Three distinct models were estimated in this research. The first was a contingent valuation model estimating the willingness to pay (WTP) for water quality improvements in the Minnesota River using only stated preference data. There were two different payment vehicles used in this question, an increase in the state income tax and a water bill surcharge. Respondents' annual mean willingness to pay for a 40% reduction in phosphorus was estimated to be $14.07 using this model and the tax vehicle, while the mean willingness to pay via the water bill surcharge was estimated to be $19.64 annually. The second model utilized stated preference data from respondents along with responses about their actual visit behavior. A panel model was constructed using the responses to three separate questions concerning the value of a 40% reduction in phosphorus pollution and yielded an estimate of $38.88 per year. The final model used only data from the subset of respondents who had actually visited the Minnesota Valley National Wildlife Refuge. The recreational value of a typical trip to the Refuge was estimated to be $28.71 per individual.