California Agriculture

In many parts of coastal California, agricultural water needs during the summer are met by tapping riparian and groundwater resources, which has led to documented decreases in stream flow during the dry season. This has consequences for salmon, including sudden drying of habitat, higher water temperatures and changes in the invertebrate prey base. We developed a new, spatially explicit analytical tool to quantify and map human and environmental needs, model daily stream-flow rates, and estimate regulatory flow requirements and cumulative impacts of reservoirs. This tool is part of a decision support system that can be integrated in a Geographic Information System (GIS) with other restoration considerations. This research provides a basis for placing additional reservoir storage where projects are not likely to affect adult salmon passage, while reducing water demand from surface and subsurface flows during spring and summer, ultimately improving both habitat for salmonids and water supply for growers.