May 11, 2004 > Water, Our Precious Resource: Part II
Water, Our Precious Resource: Part II
A panel of experts from Alameda County Water District (ACWD) agreed to talk with Tri-City Voice about Water Resources Planning and water quality activities at the District. The panel included Paul Piraino, General Manager; Karl Stinson, Operations Manager; Bob Shaver, Engineering Manager; Doug Chun, Water Quality Manager; Steven Inn, Groundwater Resources Manager; Jim Reynolds, Water Supply Engineer; Mike Halliwell, Groundwater Resources Engineer; Eric Cartwright, Senior Water Resources Planner. Part I of this series (TCV April 13 - 27, 2004) outlined the sources of water for the Tri-Cities.
Water resources planning in the Tri-Cities is the result of an "Integrated Resources" planning process that forecasts demand using both historical data and general plans (growth) of cities served. This estimate is compared with supply, storage considerations and other ACWD policies resulting in a strategy that meets future estimated demands through a variety of capital projects and other actions to be taken by the District, through the year 2030. Public input was solicited during the initial Integrated Resources Planning Study completed in 1995 and the accompanying Programmatic Environmental Impact Report. The short explanation is that it takes a lot of planning to make sure there are adequate supplies of high quality water to meet local water requirements both throughout the year and for years to come.
The District's development of several sources of supply (imported State Water Project Water, water purchased from the San Francisco Public Utilities Commission, local groundwater and desalinated brackish groundwater) affords the District considerable flexibility in periods of extended drought, changes in availability and cost. For example, aquifers under the surface act as "underground reservoirs" that can help smooth out seasonal demands and drought impacts. During the winter and spring runoff season, the groundwater level may rise from 10 feet above sea level to 18 or 19 feet and then settle back down as summer demands exceed incoming supplies. Local usable storage in the groundwater basin is approximately 20,000 acre feet annually (an acre foot is 325,900 gallons). Average daily consumption of the ACWD service area is about 45 million gallons!
Another reserve held by ACWD is off site storage in the "Semitropic Groundwater Banking Program" in Kern County. When ACWD is "water rich" due to abundant supplies, a portion of its State Water Project allocation can be diverted through the California Aqueduct to the Bakersfield area and stored in the groundwater of that district. This acts as a "bank" for dry years.
In a dry year or extended drought conditions when additional water resources may needed, ACWD can call upon these reserves to supplement its supplies. This is a key dry year reserve that has a storage capacity of 150,000 acre feet. About half (71,672 acre feet) of that total capacity is now in storage, creating a significant buffer for long-term drought conditions.
Desalination of brackish groundwater offers another cushion against the impact of an extended drought and it currently it represents ten percent of the District's average daily demand. Pumping this trapped brackish water from pockets of the aquifer also allows the District to reclaim these portions of the groundwater basin for fresh water storage. The ACWD Groundwater Resources group monitors wells for water levels and chloride concentration - a high concentration indicates brackish water - to inform the district of the status of groundwater aquifers. Measurements from hundreds of wells are taken in the spring to study a traditional high water period and in the fall for low levels. ACWD also works with state and local governmental agencies to investigate potential threats to the groundwater supply. Contamination problems have been contained in a shallow water zone and remedial actions taken before the problem can spread to deeper zones where drinking water is stored. Also, most "production wells" are located up-gradient (at higher elevation) from gas stations and industrial zones.
Assuring supply is only one part of the story. Once water is available, ACWD has the responsibility of assuring customers that the water is safe to drink. The local aquifer system provides a natural filter for surface water from Alameda Creek that percolates into the underground basin. However, all ACWD water must meet rigorous requirements before it is released for consumption. About 70,000 tests to analyze ACWD water are performed every year. These include physical, chemical, bacteriological and "flavor profile" analyses.
Testing ranges from "continuous" to periodic. At each treatment facility, on-line monitoring is constant as well as by "grab samples" taken manually and analyzed. An automatic monitoring system on Alameda Creek will notify the district of any contamination problems immediately allowing time to seal off the percolation facilities from the creek. The headquarters laboratory, staffed seven days a week, sends someone out every day to take samples that are analyzed for many components, but key among them is bacterial contamination. On average, about two hundred tests are run every day to assure water quality of ACWD.
According to Water Quality Manager, Douglas Chun, P.E., ACWD "easily meets or surpasses all federal and state drinking water standards." He says that often the perception of ACWD water is influenced by comparisons with other water sources in the Bay Area. For instance, Hetch-Hetchy water is primarily snow melt and very "soft" with little mineralization. Softer water will lather soap more easily and leave fewer deposits when it dries. Groundwater contains a much higher concentration of minerals, resulting in harder water. To address this problem, ACWD blends groundwater and softer Hetch-Hetchy water to moderate the effects of mineralization. A number of projects are also in line to help reduce hardness, including creating additional capacity to blend groundwater Hetch-Hetchy water (2005), as well as construction of a groundwater demineralization facility (2006). The goal is to create a lower hardness and more uniform water taste and hardness throughout the system even though different areas of the district are served by a variety of sources.
Although the ACWD system is integrated to provide maximum safety and hardness uniformity, planning includes the possibility of separation due to disasters such as a major earthquake along the Hayward Fault. Supply sources are found on both sides of the fault line and contain reserves in the event of a break at the fault. While ACWD staff has worked to assure smooth delivery of water, even in difficult times, there is no substitute for citizen preparedness. ACWD urges all residents to store a minimum of three gallons of water (one gallon per person per day) for each household occupant (don't forget your pets). Additional tips can be found at www.acwd.org.
The next installment of Water, Our Precious Resource will examine maintenance, construction and quality controls necessary to ensure a steady and safe supply of water for the Tri-Cities.