We analyze willingness to pay (WTP) for environmental programs whose time periods of benefit and repayment differ, using a net present value framework that identifies parameters of both WTP and personal discount rates. Respondents to a contingent valuation survey focusing on protection of critical habitat buffer zones for the endangered Steller Sea Lion in Alaska were asked their willingness to pay for 1-, 5-, and 15-year repayment periods. We jointly estimate the personal discount rates and WTP via maximum likelihood, and compare with a model assuming a fixed, market discount rate. (C) 2009 Elsevier B.V. All rights reserved.