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Water Supply

Russian River Water Supply Report (Updated 7/01/08)

Press release: Severe dry spring means using less water

California State Water Resources Control Board

Agency presentation on May 6 in Sacramento, CA

Water Supply Forecast
The terms of the Agency's water rights permits define what constitutes "normal," "dry," and "critical" water supply conditions based upon cumulative inflow into Lake Pillsbury since the beginning of the water year (October 1). The cumulative inflow on May 1, 2008, was 266,558 acre-feet, well above the level needed for "normal" water supply conditions to exist through the end of the calendar year. The water supply pools at Lake Sonoma, Lake Mendocino, and Lake Pillsbury are approximately 97.5, 86.2, and 84.4 percent full, respectively. Lack of rainfall and reduced flows of water to the East Fork Russian River from Pacific Gas & Electric Company's Potter Valley Project may reduce the water supply available from the Russian River this summer. The Agency is continuing to monitor the situation. As always, water should be used wisely and efficiently.

Warm Springs Dam/Lake Sonoma

Stage: 443.68 feet (Maximum allowed: 451.1 feet)

Storage: 226,068 acre-feet (Maximum allowed: 245,000 acre-feet)

Rate of Release: 126 cubic-feet-per-second (cfs)

Required Dry Creek Flow Rate: 80 cfs

Coyote Valley Dam/Lake Mendocino

2008 water supply projection

Stage: 735.73 feet (Maximum allowed: 761.8 feet)

Storage: 65,480 acre-feet (Maximum allowed: 116,700 acre feet)

Rate of Release: 184 cfs

Required Upper Russian River Flow Rate: 75 cfs

Rate (Coyote + West Fork): 186

Scott Dam/Lake Pillsbury

Storage: 52,585 acre-feet (Maximum allowed: 78,901 acre-feet)

Rate of Release: 156 cfs

Cape Horn Dam/Lake Van Arsdale

Potter Valley Diversion: 131 cfs

Eel River Release: 19 cfs

Hacienda Bridge

Rate of Flow: 134cfs

Required Lower Russian River Flow Rate: 125 cfs

View current Russian River water levels.

BACKGROUND

The Sonoma County Water Agency was created as a special district in 1949 by the California Legislature to act as the local sponsor for federal flood protection and water supply projects known collectively as the Russian River Project. The Sonoma County Board of Supervisors acts as the Water Agency's Board of Directors. The Agency is authorized to produce and furnish surface water and groundwater for beneficial uses, and control floodwaters. Legislation enacted in 1994 added the treatment and disposal of wastewater to the Agency's responsibilities.

RUSSIAN RIVER SYSTEM Back To Top

The Russian River originates in central Mendocino County, approximately 15 miles north of Ukiah. It drains 1,485 square miles including much of Sonoma and Mendocino counties, and reaches the Pacific Ocean at Jenner, 20 miles west of Santa Rosa. Its main channel is 110 miles long and flows generally southward from its headwaters near Redwood and Potter Valleys, to Mirabel Park, where the direction of flow changes to generally westward as it crosses part of the Coast Range. There are five principal tributaries: the East Fork of the Russian River, Big Sulphur Creek, Mark West Creek, Maacama Creek, and Dry Creek.

Three major reservoir projects provide water supply for the Russian River watershed: Lake Pillsbury on the Eel River, Lake Mendocino on the East Fork of the Russian River, and Lake Sonoma on Dry Creek. Lake Mendocino and Lake Sonoma provide water for agriculture, municipal and industrial uses, in addition to maintaining the minimum stream flows required by Agency water rights permits. These minimum stream flows provide recreation and fish passage for salmon and steelhead. Most of the streamflow in the Russian River during the summer is provided by water imported from the Eel River. Streamflows are augmented by releases from Lake Mendocino and Lake Sonoma.

Scott Dam: This concrete gravity dam on the Eel River captures a drainage area of 298 square miles and forms Lake Pillsbury. View Scott Dam.

Lake Pillsbury: Lake Pillsbury has a storage capacity of 86,388 acre-feet. Since 1923, the lake stored water for diversion to the Potter Valley Project through a tunnel constructed through a mountain ridge. View Lake Pillsbury.

Coyote Valley Dam: Located on the East Fork of the Russian River, this rolled earth embankment forms Lake Mendocino.

Lake Mendocino: This U.S. Army Corps of Engineers project began storing water in 1959. It captures a drainage area of about 105 square miles, and provides a total storage capacity of 118,000 acre-feet with a water supply pool of 70,000 acre-feet. View Lake Mendocino.

Warm Springs Dam: Located about 14 miles northwest of Healdsburg, this rolled earth embankment dam forms Lake Sonoma. The Sonoma County Water Agency generates electricity at Warm Springs Dam and sells the power to PG&E to offset the Agency's energy costs. View Warm Springs Dam.

Lake Sonoma: Located at the confluence of Warm Springs Creek and Dry Creek, this lake began storing water in 1984 and has a total storage capacity of 381,000 acre-feet with a water supply pool of 212,000 acre-feet. View Lake Sonoma.

Visit the Army Corps of Engineers Springs Dam & Lake Sonoma Project Site at http://www.spn.usace.army.mil/projects/o&mlakesonoma.html

RIVER MANAGEMENT SYSTEM Back To Top

Ranney Collector

Mirabel & Wohler Collectors: The Agency has constructed six collector wells adjacent to the Russian River— two collectors near the Wohler Bridge and four collectors at Mirabel Park. Water is extracted by each collector from the deep gravel underflow of the Russian River. A typical collector has a 13-foot diameter concrete caisson (pipe) extending 50 to 60 feet below the surface of the natural streambed. Perforated pipes (horizontal wells) extend radially from the bottom of each caisson into the aquifer. Each collector well houses two large electric pumps.

Infiltration ponds: In the summer, algae can plug the riverbed and cause a reduction in the water reaching the gravel underflow. Cleansing winter floods restore infiltration in the riverbed, but during late summer and fall it is necessary to augment infiltration by diverting water to infiltration ponds. Fish-screening facilities ensure that fish are not diverted from the river into the infiltration ponds.

Inflatable rubber dam: The rubber dam is raised in the spring when potable water demand increases. The dam raises the water level and creates a small lake from which to draw water into the off-stream infiltration ponds. Permanent fish ladders provide fish passage when the dam is raised.

Well Field: As a stand-by water source, seven wells have been added near the Mirabel collectors, providing up to an additional 5-15 mgd (million gallons per day) of pumping and diversion capacity.

Chlorination facilities: The natural water entering the collectors is extremely clean; however, chlorine is added as a precaution against possible contamination in the distribution system.

pH Adjustment/Corrosion Control System: The Russian River water has a natural pH of about 7.1 - 7.6. To reduce corrosion of lead and copper present in indoor plumbing fixtures, it is desirable to raise the pH of the river water to 8.3 - 8.5. The Agency operates pH Adjustment/Corrosion Control facilities, located at the Wohler pumping plant and at the chlorination facility, where sodium hydroxide is added to the water supply. This treatment helps reduce dissolved metal content in recycled water as well.

AQUEDUCT TRANSMISSION SYSTEM Back To Top

Cotati Tanks The aqueduct system consists of storage tanks, pipelines, booster (pump) stations and emergency wells and is designed to carry the anticipated (average) daily demand during peak demand. Maximum demand usually occurs during July or August.

Tanks: Eighteen steel water storage tanks placed throughout the transmission system store about 128 million gallons.

Pipelines: The Agency has about 79 miles of underground pipeline extending from the Russian River to Santa Rosa, Cotati, Petaluma and Sonoma. The pipes range in size from 16 inches to 48 inches in diameter.

Santa Rosa Plain wells: Three wells are capable of providing about 4-6 million gallons per day, and were constructed in 1977 in response to drought conditions.

Booster stations: Seven booster stations are located in the water transmission system with pumps to maintain water flow within the aqueducts.

WARM SPRINGS DAM Back To Top

Completed in 1983 this multi-purpose reservoir serves as a flood control, water supply and recreational facility. The Water Agency is the local cost-sharing partner for Warm Springs Dam, and determines the amount of water to be released when the lake level is in the water supply pool, and the US Army Corps of Engineers manages flood control releases.

WATER RIGHTS Back To Top

As early as 1954, the Sonoma County Water Agency applied to the State Water Resources Control Board, which has the authority over water rights, for rights to appropriate Russian River water. Riparian water rights entitle the owner of land containing or abutting a natural stream the right to use natural flows by direct diversions for beneficial purposes without a permit. If water is to be stored for use in another season, owners must obtain an appropriative water rights permit. As the local project sponsor for the construction of the Coyote Valley and Warm Springs dams, the Agency retains rights to some of the water stored in these reservoirs and controls the releases from the reservoirs' water supply pools. The Agency also has rights for direct diversion and rediversion of water at the Wohler and Mirabel collectors. The Agency is required to maintain minimum streamflows, according to Decision 1610, at various points on the Russian River and Dry Creek in accordance with its water rights permits.

WATER QUALITY Back To Top

In addition to its water rights permits, the Agency operates under a water supply permit issued by the State Department of Health Services. This permit requires the Agency to operate and maintain its water supply system in compliance with state water law. This permit includes water quality monitoring requirements and various other conditions and criteria. The Agency consistently meets state and national standards for drinking water quality.

The quality of drinking water is generally considered in two ways: the presence of contaminants that might cause adverse health effects, and properties of water that affect aesthetics. Contaminants that may cause adverse health effects include inorganic and organic chemicals, and microbiological contaminants. The aesthetic qualities of drinking water include characteristics that make the water unpalatable or bothersome to customers. Examples are hardness, taste, odor, color, and the tendency to discolor plumbing fixtures.

Until 1995, Agency water received only chlorination to provide residual disinfection throughout the transmission system. In 1995, the Agency began adjusting the pH of its water with sodium hydroxide to address the inherent characteristics of Russian River water that tend to corrode copper plumbing.

The majority of Sonoma County residents are fortunate to have a water supply system that consistently provides some of the highest quality drinking water available. Because of the unique nature of the Ranney collector well system the water supply has been free from most of the water quality concerns that affect most public water systems throughout the United States. Maintaining the high quality of water will continue to be one of the Sonoma County Water Agency's highest priorities.