Date of Award


Degree Name

MS in Environmental Sciences and Management


College of Agriculture, Food, and Environmental Sciences


Dr. Chris Surfleet

Advisor Department

Natural Resources Management

Advisor College

College of Agriculture, Food, and Environmental Sciences


The Watershed Sanitary Survey update evaluates the water quality of a groundwater aquifer utilized by the community of Santa Margarita as a municipal water source through Well No. 4. It was last conducted in 2011. The Watershed Sanitary Survey is a regulatory document for the compliance of Santa Margarita’s water system with the Surface Water Treatment Rule (SWTR), aimed at protecting the public from any sources of drinking water contamination. The unprecedented level of drought occurring over the last five years could spell unknown changes to the water quality of the aquifer, possibly increasing the concentration of pollutants. This poses new risks to public health and sanitation that could compromise the use of Well No. 4. Water quality was evaluated by identifying, examining and summarizing constituents of concern and if they exceeded allowable regulatory levels. Rainfall and well depths were summarized to determine the severity of drought conditions and to compare with water quality metrics to determine any possible patterns. Data was collected from 2011 to 2020, following the last published survey in 2011. Despite the lack of precipitation, water quality and well depths of Well No. 4 remained largely unchanged. Bacteriological results indicated no presence of E. Coli, with only four detections of naturally occurring total coliforms. Results for metals, turbidity, minerals, surfactants, nitrates and nitrites were all under regulatory limits. Well depths did not reach critical thresholds despite lack of recharge from precipitation. Over the last 10 years, Well No. 4 met all water quality standards even in critical drought conditions. Its groundwater continues to be of excellent quality and can continued to be used as a municipal water supply as long as current disinfection practices remain in place.