南加州大都会水区是一个区域公共机构，负责开发、储存、处理补充水，并以批发价格向27个成员机构分配生活和市政用水，并为农业提供剩余水。评估当地地下水供应状况很重要，因为任何损失都会给该地区有限的进口供应带来更大的压力，而盆地污染限制了联合使用和储存的机会。本文描述了服务区地下水质量状况的综合评估，涵盖了南加州的15个主要地下水盆地。 开发了一个广泛的地下水数据库，包括从46个公共机构收集的现有数据，包括200种水质成分的浓度和3500口市政供水井的生产信息。从1976年到1989年的分析期间，得出了每年140万英亩英尺的区域地下水质量和生产条件。根据可用数据进行线性推断，以预测整个服务区的影响。

The Metropolitan Water District of Southern California is a regional public agency responsible for developing, storing, treating and distributing supplemental water supply at wholesale rates to 27 member agencies for domestic and municipal uses, and provides surplus water for agriculture. It is important to assess the condition of the local groundwater supply, as any loss puts more pressure on the District's limited imported supplies, and basin contamination restricts conjunctive-use storage opportunities. This paper describes the comprehensive assessment that was made of groundwater quality conditions in the service area, covering 15 major groundwater basins in Southern California. An extensive groundwater database was developed, consisting of existing data collected from 46 public agencies, including the concentrations of 200 water quality constituents and production information for 3,500 municipal water supply wells. The analysis period, from 1976 to 1989, yielded regional groundwater quality and production conditions for 1.4 million acre-feet per year. A linear extrapolation was made from available data to project the impacts for the entire service area.