source water assessment report

The Source Water Assessment identifies activities to which water sources are considered “most vulnerable.” There were NO contaminants from the “possible contaminating activities” found in Sweetwater Authority’s water supplies.

Recently enacted Federal and State laws require that either the California Department of Health Services or the water suppliers evaluate every water source in California to determine the vulnerability of the sources to “possible contaminating activities” that could lead to contamination of a drinking water source. In 2002, source water assessments were completed for Sweetwater Authority’s water supplies.

The following report discusses Sweetwater Authority’s sources of supply and the “possible contaminating activities” to which the sources are considered to be “most vulnerable.” To request a summary of the assessments, please contact Dorothy Ryan, Water Quality Secretary, at (619) 409-6804 or dryan@sweetwater.org.

The California Department of Health Services considered the following factors to determine where each water source was “most vulnerable”:
- the presence of a “possible contaminating activity”
- the proximity of the activity to the source
- the risk associated with the activity
- the construction and setting of the source.

The factors were combined to develop a priority ranking. The source is considered to be “most vulnerable” to those activities at the top of the ranking. Listing an activity as “most vulnerable” does not mean that any related contamination was found in the water supply.

Sweetwater Authority proactively protects and monitors its water supplies. The agency participates in a nationwide screening program for potential contaminants conducted by the U.S. Geological Survey, controls urban runoff flows to Sweetwater Reservoir, monitors development within the watershed, reviews development plans, and requests conditions on projects that could impact the Sweetwater River water supply.

Imported Water Supply
Metropolitan Water District of Southern California completed its source water assessment of its Colorado River and State Water Project supplies in December 2002. Colorado River supplies are considered to be most vulnerable to recreation, urban/storm water runoff, increasing urbanization in the watershed and wastewater.

State Water Project supplies are considered to be most vulnerable to urban/storm water runoff, wildlife, agriculture, recreation and wastewater.

Sweetwater Authority treats the imported water supply at the Perdue Water Treatment Plant. The water undergoes complete “conventional” water treatment, including filtration and disinfection, before it is delivered. Alternatively, imported water can be added to Sweetwater Reservoir where it is blended with the local water supply before being treated at the Perdue Plant. Occasionally, Sweetwater Authority may purchase water that has been treated by Metropolitan Water District’s filtration plants using treatment technology similar to that of the Perdue Plant. Before it is delivered to customers, the water is tested to assure that it complies with all State and Federal standards.

Sweetwater and Loveland Reservoirs
Sweetwater Reservoir receives water from three sources: runoff from the Sweetwater River watershed; imported water; and released water from Loveland Reservoir (releases occur only when the quantity and quality of the water is sufficient).

There have been NO contaminants detected in the Sweetwater and Loveland Reservoirs. However, the supplies are considered to be most vulnerable to the following activities located nearby: a recreation area on a surface water source.

The two primary activities of concern for Loveland Reservoir are the use of the lake area for non-body contact recreational activities such as fishing and horse riding, and the Viejas Landfill eight miles upstream of Loveland Reservoir.

Possible contamination resulting from surface water recreation is limited because body contact activities and boating are prohibited. Prior to 1997, when Sweetwater Authority began operating the fishing program at Loveland Reservoir, fishing had been allowed within the boundaries of the Cleveland National Forest. There were no sanitary facilities provided on the U.S. Forest Service lands leading to concerns that water quality could become compromised. In 1996, Sweetwater Authority negotiated a land exchange with the U.S. Forest Service and relocated the fishing access to property owned and controlled by Sweetwater Authority. Since Sweetwater Authority began operating the shoreline fishing program, in January 1997, the unsupervised activities have been greatly curtailed.
The location of the small Viejas Landfill eight miles upstream of Loveland Reservoir contributes total dissolved solids (salts) to the groundwater, but is sufficiently distant to permit any effects to be negligible.

The two primary activities of concern for Sweetwater Reservoir are the use of the lake area for non-body contact recreational activities (such as the fishing program at Loveland Reservoir and horse riding), and the Jamacha Landfill three miles upstream of Sweetwater Reservoir.

Possible contamination resulting from surface water recreation is limited because body contact activities and boating are prohibited.

Horse riding activities occur at least 200 feet from the shoreline of the reservoir. San Diego County operates the trail through an easement that allows Sweetwater Authority to permanently close the trail if its use damages water quality or sensitive habitat.

The Jamacha Landfill is located less than three miles upstream of Sweetwater Reservoir and is within 200 feet of the Sweetwater River. The Jamacha Landfill was operated from 1960 through 1978. San Diego County monitors groundwater quality and maintains the site to ensure the proper flow of surface water. Although no alarming concentrations of leached constituents have been observed in the groundwater monitoring test results, the landfill contributes total dissolved solids (salts) and other constituents to the groundwater that eventually reaches Sweetwater Reservoir.

To protect the water in Sweetwater Reservoir, Sweetwater Authority constructed and operates an Urban Runoff Diversion System (URDS). This system captures rainfall and irrigation runoff from the urbanized areas surrounding the reservoir. Captured water is diverted through a network of channels and ponds, where its quality is tested. Satisfactory water is allowed to enter the reservoir. Water that does not meet Sweetwater Authority’s quality standards is diverted into the Sweetwater River downstream of the reservoir.

National City Wells
Sweetwater Authority operates two wells in National City. There have been NO contaminants detected in the National City Wells supply. However, the source is considered most vulnerable to the following activities located near the drinking water source: confirmed leaking tanks, a repair shop, photo processing/finishing, dry cleaners, non-regulated tanks, freeway/state highways, and a parking lot/mall.

At one confirmed leaking gasoline tank in National City, a soil vapor extraction system is currently cleaning up contaminated groundwater. Although it is the responsibility of the gasoline station owner to monitor and remediate contaminated groundwater by this facility and other confirmed leaking tanks,

Sweetwater Authority is currently monitoring the National City Wellfield on a monthly basis for MTBE contamination. Sweetwater Authority has been conducting monitoring operations since being notified by the San Diego County Health Department of leaking underground storage tanks in the area. All monitoring tests have been negative for contamination to Sweetwater Authority’s wellfield.

Alluvial Wells
Sweetwater Authority owns four alluvial, or shallow aquifer, wells. Although designed to provide water for the Reynolds Groundwater Demineralization Facility, the wells have not yet been operated as a water supply.

There have been NO contaminants detected in the alluvial wells supply. However, the source is considered most vulnerable to the following activities located near the drinking water source: confirmed leaking gasoline tanks; gas stations; dry cleaners; military installations; non-regulated tanks; a repair shop; freeway/state highways; and a park.
At one confirmed leaking gasoline tank in National City, a soil vapor extraction system is currently cleaning up contaminated groundwater. Although it is the responsibility of the gasoline station owner to monitor and remediate groundwater contaminated by this facility and other confirmed leaking tanks, Sweetwater Authority is currently monitoring the alluvial wells on a monthly basis for MTBE contamination. Sweetwater Authority has been conducting monitoring operations since being notified by the San Diego County Health Department of leaking underground storage tanks in the area. All monitoring tests have been negative for contamination to Sweetwater Authority’s alluvial wells.

San Diego Formation Wells
Sweetwater Authority owns and operates five wells in the San Diego Formation, a deeper groundwater basin. The wells are high in total dissolved solids (“salts”). The San Diego Formation wells provide water to the Reynolds Groundwater Demineralization Facility. This facility provides advanced treatment using reverse osmosis membranes and disinfection. Reverse osmosis treatment is capable of removing microorganisms, total dissolved solids, and a wide range of inorganic and organic chemicals.

There have been NO contaminants detected in the San Diego Formation Wells supply. However, the source is considered most vulnerable to the following activities located near the drinking water source: golf courses and freeways/state highways. The golf courses are a potential concern because of the pesticides, herbicides, and fertilizers that may be used. Freeways and state highways may contribute particulate matter, gasoline, motor oils, and other potential contaminants. Sweetwater Authority monitors the wells on a regular basis for these contaminants. All monitoring tests have been negative for contamination to Sweetwater Authority’s wellfield.

To learn more or become involved in source water protection, please contact Mary Ann Mann, Director of Water Quality, (619) 409-6801, mmann@sweetwater.org.