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Russian River Estuary

The Russian River Estuary closes throughout the year as a result of a sandbar forming at the mouth of the Russian River.  The sandbar usually closes during the spring, summer, and fall when river flows are relatively low and long period waves transport sand landward, rebuilding the beach that was removed by winter waves and river outflows.  Closures result in ponding of the Russian River behind the sandbar and water level increases in the Estuary.  Natural breaching events occur when estuary water surface levels exceed the sandbar height and overtop the sandbar, scouring an outlet channel.  Public agencies have been involved in breaching the sandbar since at least the 1960s.  The Sonoma County Water Agency became responsible for breaching activities in 1994.

The Sonoma County Water Agency mechanically breaches the sandbar to alleviate potential flooding of low-lying shoreline properties near the town of Jenner.  Breaching is performed in accordance with the Russian River Estuary Study 1992-1993  when the Estuary water surface level is between 1.4 and 2 meters (m; 4.5 and 7.0 feet) as read at the Jenner gage (located at the Jenner Visitor’s Center).  The Agency holds permits from the U.S. Army Corps of Engineers, California State Parks and Recreation, North Coast Regional Water Quality Control Board, California Department of Fish and Game, California State Lands Commission, and the California Coastal Commission for the breaching activities.

How the Sandbar is Breached

Breaching activities occur on the closed sandbar.  The sandbar is accessed from the paved parking lot at Goat Rock State Beach.  Equipment is off-loaded in the parking lot and driven onto the beach via an existing access point.  A bulldozer or similar equipment is used to breach the sandbar.  A cut in the sandbar is created at a sufficient depth to allow river flows to begin transporting sand to the ocean.  The sand is placed onto the beach adjacent to the pilot channel.  After the pilot channel is dug, the last upstream portion of the sandbar is removed, allowing river water to flow to the ocean.  The size of the pilot channel varies depending on the height of the sandbar to be breached, the tide level, and the water surface level in the Estuary.  A typical channel would be approximately 30 m long, 8 m wide, and 2 m deep (100 feet long, 25 feet wide, and 6 feet deep).  The amount of sand moved can range from less than 100 cubic yards to approximately 1,000 cubic yards.  The Agency contacts State Parks lifeguards within 24 hours prior to breaching activities to minimize potential hazards to beach visitors.  Signs and barriers are also posted for 24 hours prior to and after breaching events to warn beach visitors of the hazards of the breaching area.

Studies

Russian River Estuary Study

The Russian River Estuary Study, 1992-1993, was prepared for the Sonoma County Department of Public Works to evaluate the physical processes associated with sandbar closure, the changes to water quality and biological conditions following sandbar closure and breaching, the flooding impacts of sandbar closure, and develop a management plan for the Estuary.  The current management plan specifying breaching the sandbar when the water surface level in the Estuary is between 4.5 and 7 feet NGVD was a result of this plan.

Annual Biological and Water Quality Monitoring, 1996-2000

The Agency evaluated the impact of artificially breaching the sandbar at the mouth of the Russian River on water quality, pinnipeds, nekton, and fisheries from 1996 through 2000.  Monitoring included continuous water quality sampling and observations of pinnipeds, nekton, and fisheries before, during, and following sandbar breaching.

Russian River Estuary Fish and Macro-Invertebrate Monitoring

This monitoring evaluated the distribution and abundance of aquatic species in the Russian River Estuary during late spring through early fall.  The 2003 study evaluated the feasibility and effectiveness of using several field survey techniques to sample for fish and macro-invertebrates.  Subsequent monitoring in 2004 and 2005 found juvenile steelhead in the upper Estuary during the entire period and juvenile Chinook salmon in the Estuary until mid-summer.  This monitoring effort has since been incorporated into the current sandbar breaching monitoring plan.

Current Sandbar Breaching Monitoring

The Agency developed the Russian River Estuary Sandbar Breaching Monitoring Plan in 2005 in response to permit requirements from the U.S. Army Corps of Engineers and National Marine Fisheries Service.  The monitoring plan includes documenting salmonid presence in the Estuary.  The goals of the monitoring plan are to: document the distribution, abundance, and condition of listed salmonids in the Estuary; document salmonid residence times in the Estuary; and to assess the habitat parameters that affect salmonid presence and distribution in the Estuary.

The Agency is employing continuous water quality monitoring, fisheries seining, macro-invertebrate sampling, and acoustic telemetry to learn more about how salmon are using the Estuary and how they may be impacted by sandbar breaching.

 

Artificial breaching of the Russian River Estuary takes place in the late spring, fall and during dry winters to manage storm flow inflows to the Estuary to prevent flooding of local properties.  Agency staff in these photos taken in January of 2007 breach the Estuary by hand with shovels because of the difficulty getting equipment over the jetty remnants safely.  A bulldozer or excavator is typically used to open the sandbar.