AWWA SOURCES55686

South Bay Water Recycling (SBWR) is a regional program that serves nonpotable recycled water to more than 300 irrigation and industrial customers in San Jose and Santa Clara and several other communities in the Silicon Valley area of northern California. Within the past two years, power companies have proposed building nearly a dozen water-cooled electrical generating facilities within the SBWR service area, ranging in size from 50 to 600 megawatts (MW). Currently, salinity of recycled water distributed by SBWR averages between 780-800 mg/L, which is considered to be near the upper limit of salinity for certain irrigation uses. As a result the cumulative impact of blowdown from the proposed power plants could make SBWR recycled water unsuitable for various industrial, landscape, or agricultural uses, jeopardizing the entire regional program. This paper presents an approach to estimating the impact of salt discharges based on relationships between salinity and plant yield, crop quality, horticulture, and industrial use, as well as a qualitative review of customer perception issues. An economic evaluation of physical and commercial impacts is developed, along with various alternative means of regulating salinity to protect recycled water quality. This paper attempts to quantify the cumulative impact of total salinity and specific ion toxicity on agricultural and landscape irrigation and industrial reuse. Includes 20 references, tables, figures.