Local Shallow Groundwater Drawdown and Baseflow Cessation Due to Regional Groundwater Pumping

The existing concept of buffers presupposes that local-scale easements can protect ecosystem structure and function. However, regional-scale processes control many elements of ecosystem structure and function in riparian systems. In this study, we show how local-scale easements fail to protect dry-season shallow groundwater and associated baseflow from the effects of regional groundwater pumping on Little Stony Creek above East Park Reservoir on the east front of the Coast Range, California. Isotopic and geochemical procedures indicate that shallow groundwater and associated baseflow are recharged primarily by regional groundwater discharge, while hydrometric procedures suggest that groundwater pumping in the regional groundwater flow system results in shallow groundwater drawdown and associated baseflow cessation. We believe that the existing concept of buffers must be changed to reflect current understanding of ecosystem structure and function in riparian systems if resource conservation efforts are to be successful. Therefore, we propose that the existing concept of buffers be extended to include regional-scale management of areas critical to the structure and function of the larger hydrologic systems in which riparian systems exist such as groundwater recharge zones and hydrological flowpaths.