The Benutan Reservoir began to fill following impoundment in 1989, and had filled completely by 1991. Physicochemical and biological data obtained on a monthly basis since February 1990 indicate that this is a stratified, dystrophic black-water lake with low levels of inorganic nutrients, high organic loads, and high productivity. Currently (1991), semi-commercial fishing is being undertaken,
... [Show full abstract] based on seven or eight local riverine fish species which have become established in the lake. The catchment area, covered with mixed dipterocarp forest and containing abundant wildlife, is spectacular and of great biological interest. In addition to its role in the country's freshwater supply strategy, the reservoir and catchment could also be used for a variety of recreational and pollution-free economic activities which are relevant to current government policies of economic diversification and enhancement of eco-tourism and recreation. Well laid out trails, together with support facilities, could be established in the catchment forest with lake views and lake access points. The lake could be stocked with sport fish to encourage recreational angling. Non-motorized boating and water sports would be feasible on a limited scale. If well managed, such developments would optimize lake utilization and generate revenue without adverse ecological effects.