A Crisis on Three Fronts

It does not get any easier for the state Water Resources Control Board to sort out the way California’s water supply and demand affects the Sacramento-San Joaquin Delta. Now the board has a new report of potential contamination in the delta that cannot be eliminated by the modern water treatment plants now in operation. The report also heats up the debate between conservationists who want to leave more water in the delta and those who seek to export more from the estuary to farms in Central California and urban areas in both Northern and Southern California.

The state board is in the years-long process of determining how to manage delta supplies to protect the delta environment and to meet the water quality and quantity needs of exporters. The federal Central Valley Project and the state Water Project pump millions of acre-feet of water each year from the delta southwest of Sacramento. Conservation groups want pumping slowed to let more water to flow naturally through the delta into San Francisco Bay. But the state Water Project has contracted to deliver about twice as much water from the delta as it does now, and the U.S. government also wants to export more water.

The new report by a group of water agencies, scientists and environmentalists is most alarming for domestic water suppliers such as the Metropolitan Water District of Southern California. Two-thirds of all Californians receive some portion of their drinking water supply from the delta. Officials already knew that heavy pumping of water from the delta sucks salty sea water into the estuary. This mostly affected drinking water because the salt gave the water a bad taste. The new study has found that bromides in sea water are transformed into a suspected cancer-causing agent, trihalomethane (THM), when it is processed in treatment plants with chlorine or ozone.

At present, all agencies are meeting current health standards for trihalomethanes. But the Environmental Protection Agency is expected to cut the acceptable levels of THMs about in half in the next two years. There already was a known THM problem, primarily caused by agricultural runoff from farms in the delta, but existing treatment facilities have been capable of keeping it within present standards. The advanced treatment plants that would be needed to meet the new EPA standards are far more expensive than present technology and would take time to build. Cleaning their charcoal filters would contribute to air pollution and might not be allowed in California.

One short-term solution offered by water managers is to construct barriers and other structures in the delta that would limit both the agricultural runoff and sea water that gets to the pumps, or possibly to bypass the delta altogether with a slimmed-down version of the controversial Peripheral Canal for domestic water supply only. Environmentalists have said that the water managers will just have to release more fresh water through existing delta channels, but this would seriously deplete reservoir supplies and might not be possible at all during drought periods.

California’s available water supplies are shrinking every day in the face of population growth. The delta environment is under unacceptable stress. The situation is further aggravated by the new report on bromide contamination. Perhaps now the governor and legislative leaders can be persuaded that California faces a combined crisis of water supply, environmental protection and growth that commands their immediate and urgent attention.