An incomplete demand system is developed for recreation and donation choices, subject to both money and time constraints. The model results in a three-good system, with an endogenous marginal value of time for estimation. The model is implemented by adapting Deaton and Muellbauer's locally flexible almost ideal demand system to a two-constraint recreation model of trips and donations of California whale watchers. Exact welfare measures are calculated for changes in costs, as well as for whale population changes. Results indicate a use and a nonuse component of overall willingness to pay for increases in environmental quality.