Winter storms brought heavy snowfall to the Sierra Nevada and other California mountains in December. Snow accumulation is critical to the state’s spring water outlook because when snow melts, it runs down streams that fill reservoirs that hold about 30% of the state’s water supply . This water is moved throughout the state via the State Water Project and the Central Valley Project (CVP).
On December 30, the Sierra snowpack was estimated to be about 160% of the average for that date. By early February, the snowpack had fallen to 92% of the historical average for that period, according to state data. The snowpack begins to melt due to abnormally warm temperatures and dry weather.
Our Water Year begins October 1 as the state collects most of its precipitation during the months of November through April, better known as the “wet season.” Some long term forecasts show that it will be dry for the rest of our rainy season this year.
Warmer temperatures lead to higher evaporation rates. This affects how much water goes down into state and federal reservoirs and what water will be allocated to our county later this year.
San Benito County Water District (SBCWD) is a US Federal Bureau of Reclamation (USBR) contractor and imports water from CVP. Our county’s share of this water is stored in the San Luis Reservoir before being pumped through Pacheco Pass to our county.
Imported surface water helps maintain the balance of our local groundwater basin, is used to improve the quality of our drinking water, and helps produce high quality specialty crops.
Groundwater is used when surface water supplies are reduced due to drought or environmental needs in the delta, and groundwater is replenished when surface water supplies are available. Groundwater quality in our basin can be described as naturally harsh (typical of similar basins in the Coast Range) and less than ideal for drinking and agriculture. Although groundwater is considered hard, it has been and is being used for a range of beneficial uses with reasonable accommodation from users.
Over the past decade, our county’s average import surface water delivery allowances have tended to decline. On average, SBCWD received approximately 30% of its Federal Government Contract Amount (CVP) for surface water deliveries.
To help offset this deficit, SBCWD worked with the City of Hollister to build a water recycling facility at the city’s reclamation plant. This project is very efficient because the imported water is first used as drinking water for urban areas. When the imported water leaves residents’ homes as sewage, it goes to the reclamation plant where it is treated and used for agricultural and landscaping purposes.
The SBCWD also purchases water on the spot market to help offset the CVP’s small allocations of surface water deliveries. There are contracts and agreements with other agencies to acquire this water. However, this water can be quite expensive.
The SBCWD also stored water during wet years with higher allocations in a groundwater bank in the Central Valley. But this too has drawbacks. Storage has costs and a considerable amount of water is lost due to evaporation and/or infiltration when water is exchanged.
The District Manager is always looking to the future and planning for the next water year. Surface water storage is important due to variability in CVP water due to drought and environmental concerns.
The SBCWD “carries” water when it can. Residual water is the water supply that a district does not use in a previous hydrological year and which can be stored in CVP reservoirs. Each contractor has a certain “carry-over capacity” negotiated in the contract that allows them to store up to this amount in CVP tanks, particularly in San Luis. Typically, this “waste water” is subject to loss if the USBR needs capacity.
Many districts have purchased reserve water in recent years to compensate for unreliable or, in some years, non-existent CVP supplies. Last year, for example, the SBCWD only received 2,000 acre-feet of water from the CVP, but was able to provide 12,000 acre-feet of water to customers due to water deferral.
Other ideas are explored on how to store water in wet years that can be used in dry years. One idea is for an Aquifer Storage and Recovery (ASR) project. Aquifer storage and reclamation is a man-made or man-enhanced natural process that transports water underground. The process replenishes groundwater stored in aquifers for beneficial purposes. ASR is used to store water, which is then collected for use.
ASR projects are increasing across the country, especially in areas with potential for water scarcity. ASR projects are frequently found in areas of the United States that have high population density, proximity to intensive agriculture, dependence on and growing demand for groundwater for drinking water and agriculture, and the availability limited ground or surface water.
The purpose of ASR is to replenish water from an aquifer. The stored water can be recovered from the same well used for injection or from nearby injection or recovery wells.
Water managers, state officials and elected officials are all working to diversify, improve and strengthen our water supply. However, we still need each person to use water efficiently and conserve as much as possible, because water is a finite resource. Not just when we’re in a drought, but always.
The first thing to do is call the San Benito County Water Resources Association (WRASBC) for a free leak check and irrigation system assessment and evaluation. WRASBC represents the City of Hollister, City of San Juan Bautista, Sunnyslope County Water District, and San Benito County Water District in all of their water conservation and water resource protection programs .
The WRASBC can be contacted at: 831.637.4378 or check their website at www.wrasbc.org for a list of water saving programs, services and ideas.
Shawn O. Novack is the manager of water conservation programs for the San Benito County Water Resources Association and the San Benito County Water District.