This study used stated preference methods to estimate the economic value of protecting water quality in the Catawba River basin of North and South Carolina at its current level. Telephone interviews were completed with 1085 randomly selected households, who were also mailed a short information booklet about these issues. Respondents expressed a mean willingness to pay $139 for a management plan designed to protect water quality at its current level over time. Aggregation of this mean willingness to pay value amounted to an annual economic benefit of over $75 million for all taxpayers in Catawba basin counties. By using a split-sample survey design, this study also compared the effectiveness of different combined mail and telephone survey formats. Results indicated that while a phone-mail-phone approach is preferred for some reasons over a mail-phone approach, the survey format did not significantly affect the economic valuation results.