May 22, 2007 > Water - Are we tapped out?
Water - Are we tapped out?
A dry year in the Bay Area usually initiates media drumbeats of impending doom. Low snow levels in the Sierra-Nevada Mountains are met with cries of apocalyptic repercussions incorporated into headlines. The assumption is often made that we are a population living on the edge of annihilation with little or no reserves. Although these assertions can be traced to some basis in fact, headlines do not tell a complete story and often lead to erroneous conclusions.
TCV asked General Manager, Paul Piraino and Water Resources Planning Manager Eric Cartwright of Alameda County Water District (ACWD); communications and public relations manager Susan Siravo of Santa Clara Valley Water District (SCVWD) and Senior Maintenance Supervisor Steve Smith of Milpitas Public Works (MPW) to comment on current water conditions for local customers.
TCV: Where does the water of your district come from?
SCVWD: 50 percent of the water is groundwater stored here and the other 50 percent is imported from the Sierra Nevada via the Delta. A very small portion of our water comes from Hetch-Hetchy. We are a wholesale distributor of water in our area except we do sell direct to customers with wells.
ACWD: We have four sources of supplies - the state water project, South Bay Aqueduct from the Delta which accounts for about 40% of our supply. The San Francisco Public Utilities Commission (Hetch-Hetchy) supplies about 25% and local ground water as well as desalinated brackish water makes up the remainder.
MPW: Our water comes from two sources, SFPUC commonly known as Hetch-Hetchy and Santa Clara Valley Water District (SCVWD). The majority of our residential water is supplied by SFPUC and industrial customers draw primarily from SCVWD. Hetch-Hetchy water comes through the same pipeline that serves Fremont.
TCV: How is water stored?
SCVWD: In percolation ponds that keep maintain a usable groundwater level in our aquifer and ten reservoirs. Our website, www.valleywater.org lists the current stream and reservoir levels in the Emergency Information section.
ACWD: Our water is stored underground in a natural aquifer that underlies the Tri-City area, called the Niles Cone Groundwater Basin. This year, water resources are about 70 percent of normal. Snow pack in the Sierras is about 30 percent of normal. Overall, this means that replacing water in reservoirs will not be at a normal rate. That is the big concern.
TCV: What reserves does your organization have?
SCVWD: Our reservoirs and aquifer hold reserves for dry years, but a severe drought would create a severe strain on our resources.
ACWD: We have a limited amount of dry year reserves in our groundwater storage. ACWD has also invested in an off-site groundwater basin program called the Semitropic Groundwater Banking Program in Kern County. Our current storage capacity at that site is about 150,000 acre feet. Currently we have about 130,000 acre feet in storage that has been accumulated over the last 10 years. In wet years, we take a portion of our state water project allotment and save it. An acre foot of water is 328,000 gallons. In a typical year, we use 50,000 acre feet of water.
There are interconnections between water agencies - ways of moving water around in case of emergency. For instance, there are connections between SFPUC and East Bay Municipal Utility District (EBMUD) as well as ACWD, Hayward and Milpitas.
MPW: About 16.5 million gallons of water is currently in storage - about 11 million gallons of SFPUC water and 5 million gallons of SCVWD water. This represents approximately three days of water use. We also have an emergency well with another under construction. These tap into the aquifer monitored and metered by SCVWD.
TCV: What conservation plans do you have for this year?
SCVWD: We offer tips to consumers to conserve water and have, for instance, a free program called Water Wise House Calls which sends a crew to a home to assess and save water usage. Even though we are in good shape this year, if next year is dry and signals a drought cycle, we will have problems and evaluate our options.
ACWD: We always encourage water conservation but are affected by SFPUC actions which may cause us to be more aggressive in our conservation efforts. Our reserves allow a more flexible approach. The more people conserve this year, admittedly a dry year, the more it will reduce the impact if next year is dry as well.
Our customers have done an excellent job over the years using water wisely. If you compare where we were at the start of the last drought between 1987 and 1992, our average single family residential water use was 50 gallons per day higher than it is today. Per capita usage has reduced by 15 percent over the same time period. This is due, in part to technological advances, but also a water conservation ethic that has been adopted. We are balancing long range projections with storage plans.
MPW: There will be public outreach and tips on how to conserve. We structure our rates to discourage excessive use of water. Our department is echoing what other water agencies are telling the public. This year is not an emergency situation but if the dry weather continues, next year could be close to it. Storage capacity in reservoirs is limited since water needs to be pumped out in the fall for runoff from winter rain.
For water conservation tips and more information about your local water district, call or visit one of the following websites.
Alameda County Water District
Santa Clara Valley Water District
Milpitas Public Works