Watershed management for water quality protection: Are GIS and simulation models THE answer?

Managing various land uses in watersheds is advocated by many natural resource agencies as THE answer to our agricultural NPS water pollution problems. These agencies often propose using geographic information systems (GIS) to manage the massive quantities of data required to run models to predict the exact sources of pollution and the land use changes required for meeting water quality objectives. As a scientist, I prefer more precise measurements and predictions. In fact, as early as 1985 I was advocating the use of simulation models for “micro-targeting” our conservation efforts in order to increase the environmental efficiency of our conservation expenditures (Lovejoy et. al. 1985). However, from the perspective of a local manager, land owner, taxpayer, or environmentalist, I am also concerned about the cost of acquiring and using the information necessary to utilize GIS and simulation modes for making better land-use decisions. In addition, it may be more important for local hnding, public relations, and so on, to achieve short-term goals of improving water quality.The data necessary to utilize simulation models (for example, AGNPS, ANSWERS, GLEAMS, SWRRB, etc) are substantial. The models need spatially orientated information on soils, present and future land use