U.S. Water News Online
SACRAMENTO, Calif. -- As California copes with its largest flood event in a decade, the quality of drinking water supplies from the Sacramento-San Joaquin Delta continues to be high, according to officials at the California Department of Water Resources.
In fact, officials say recent California floods have freshened Delta waters. Extremely high Sacramento and San Joaquin River flows, concurrent with the flooding, are pushing fresh water through the Delta and into San Pablo Bay. The Delta Outflow Index, a measure of fresh water discharged to San Pablo Bay, exceeded 500,000 cubic feet per second during New Years week and was 360,000 cfs as of Jan. 8. These values are about 10 times the values during early December outflows.
Salinity measurements at the state and federal pumping facilities are running about 60 percent lower than before the floods. This trend is expected to continue.
The Department of Water Resources provides water supplies to millions of Californians from the Delta through the State Water Project (SWP) and its 29 long-term contractors. Once treated, SWP water meets stringent drinking water quality standards of both the U.S. Environmental Protection Agency and the State Department of Health Services.
DWR routinely conducts extensive monitoring for water quality in both the Delta and the State Water Project system. During the flooding the agency increased monitoring in both locations.
Salinity intrusion into drinking water supplies from the Delta is not a problem, according to David Spath, chief of the Drinking Water Program for the State Department of Health Services. Spath said the huge storm runoff of fresh water through the Delta makes salinity intrusion impossible.
"From the salinity standpoint, we view it as a non-issue," said Spath. "We're not looking at this as a water treatment problem."
Spath indicated that California's water systems are equipped with "more than adequate treatment capability to assure safe, high quality drinking water." Local health officers in the flood areas are taking steps to assure disinfection and safety of local water sources affected by inundation, he said.
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