Nutrient Chemistry in the Elizabeth Lake Subwatershed: Effects of Onsite Wastewater Treatment Systems on Groundwater and Lake Water Quality, Los Angeles County, California

Nutrient (nitrogen [N] and phosphorus [P] chemistry) down-gradient from onsite wastewater treatment system
(OWTS) was evaluated with a groundwater study in the area surrounding Elizabeth Lake, the largest of three sag lakes within the Santa Clara River watershed of Los Angeles County, California.

Elizabeth Lake is listed on the “303 (d) Impaired Waters List” for excess nutrients and is down-gradient from more than 600 OWTS. The primary objective of this study was to develop a conceptual hydrogeological model to determine if discharge from OWTS is transported into shallow groundwater within the Elizabeth Lake subwatershed and contributes nutrients to Elizabeth Lake in excess of the total maximum daily load limit.