Ventura County’s Freeman Diversion Dam

By Sheryl Hamlin

The Museum of Ventura County hosted an on-site tour of the Freeman Diversion Dam. Two senior members from United Water Conservation District (UWCD) presented the dam and water management strategies:  Dan Detmer, Supervising Hydro-geologist, and Murray McEachron, Senior Hydrologist. Mr. Detmer focuses on groundwater, while Mr. McEachron, who has been with UWCD since 1998, focuses on surface water.

The site for the Freeman Diversion Dam is about one mile east of the 118 near Vineyard. Road access passes through private agriculture and industrial properties and near-dry percolation ponds. The “nose” of the South Mountain Ridge is visible as shown in the following picture. UWCD owns the dam, the land and the Saticoy spreading grounds.

Freeman Diversion Trough

Freeman Diversion Trough

United Water Conservation District (UWCD) is a conservation district, which was formed in 1927 as Santa Clara River Water Conservation District (SCWCD) to protect water rights in Ventura County. There are over 3000 water conservation districts in the United States. The district boundaries of UWCD cover the Santa Clara watershed from the border of Ventura and LA Counties to the Ocean. The image shows the geographic boundaries of UWCD. The Freeman Diversion dam lies within the Santa Paula Basin. UWCD is governed by a seven member, publicly elected board of directors receiving revenue from property taxes, extraction fees, recreation fees and water deliver charges. A recent report detailing the history, objectives and plans of UWCD may be viewed at this link:  “2013 Groundwater and Surface Water Conditions Report”.


UWCD Boundaries


The early mission of SCWCD was to recharge ground water against over-drafting of irrigation wells. SCWCD joined with the City of Oxnard in 1950 to form UWCD. Realizing that the Oxnard plain with its Mediterranean climate is one of the most fertile regions in California, which can produce agricultural crops essentially year-round given sufficient water, it was logical to protect and manage this resource. Three major UWCD projects include the Santa Felicia Dam (1955), the direct pipeline from the river to farms (1986), and the Freeman Dam (1991) to capture storm water and recharge the ground water.

Sea water intrusion was first noticed in the 1940’s during a major drought which caused over pumping of groundwater. Chronic over pumping can destroy the underground storage causing subsidence, as has been evidenced in the Central Valley and the Coachella Valley. Early diversion dams were made of mud and eroded easily. During the post-war growth period, the concrete plants which had been removing boulders to grind into concrete had pitted the river bed. So the idea of a permanent dam was born of necessity. The Freeman Dam would hold back the riverbed and divert storm water to farms and percolation ponds. The dam itself is 90 feet below ground and 1700 feet across the river. The dam was controversial initially, but the $2 million fish ladder appeared to be an acceptable solution at the time, per this report. The dam could have diverted more water than initially designed, but was scaled back due to concerns from public hearings.

The two pictures below show the dam in different conditions, the first with no water on the day of this tour taken from the east side and the second picture taken from the west side by UWCD from a presentation entitled “Southern California Steelhead” by Steve Howard showing a day after a storm with water running over the dam.


Freeman Diversion Dam  with no water

Freeman Diversion Dam with water

Freeman Diversion Dam with water








The dam was designed and built by UWCD in 1991 with funds it collects from fees, plus a grant from the Federal Bureau of Reclamation. The good news is that the $30 million Freeman Diversion Dam was completely paid off in 2011. The city of Ventura sued UWCD because it did not want to pay for the dam saying it received no benefit. Both parties settled out of court for a reduced sum.

The bad news is that the planning and construction of the original $2 million fish ladder is not optimal by current standards. Steelhead trout, an anagenesis of Rainbow trout, is considered an endangered species. There is a only small number of Steelhead fish who navigate the existing ladder. One reason suggested is that the current fish ladder does not provide “volitional migration” for the fish. The Wishtoya sued UWCD over the Steelhead trout in 2009.

One of the mitigation measures suggested by a panel of experts involves cutting an 80’ wide passage in the concrete dam for a “fish ramp”. The cost could equal the original cost of the dam.  The extra cost will also include more water to push through for the fish, so this will have to be compensated elsewhere with water in the system. This fish issue is not a low-cost issue for UWCD. The picture below is a computer simulation of a fish ramp taken from the report “Fish Passage for Southern California Steelhead and Pacific Lamprey at the Freeman Diversion” authored by Environmental Planning and Conservation Department of the UWCD.


Fish Ramp


In 2013, UWCD started development of a multi-species Habitat Conservation Plan in conjunction with the U.S. Fish and Wildlife Services which includes planning for the steelhead preservation and other species.

Additionally there is a joint action against UWCD filed in 2014:  Wishtoyo, CAUSE and the Center for Biological Diversity have filed a public trust complaint with the State Water Board against United for its wasteful and unreasonable diversion and use of water from the Santa Clara.

In September of 2014, the State of California has recently passed laws that change ground water management from the historic ‘drill with impunity’ model to the ‘drill with sustainability’ model. The State is giving Water Management Agencies two and a half years to get a plan and fund it. After that, the water agency has 20 years to attain sustainability. United Water will provide records on wells, extractions, water level and quality, maps and aquifer conditions to the Ground Water Management Agencies (GMA), such as Fox Canyon  GMA, who administer regulatory controls. Additionally UWCD is using these data sets to feed two computer models: ground water flow and surface water. Such data and computer models put the areas serviced by UWCD ahead of other agencies in the state because the models are driven by actual data, so that no estimates are necessary. Thus, the activities of UWCD are designed to complement the GMA.  The chart below shows the various basins and conditions within the UWCD boundaries.


Basin and Conditions within UWCD boundaries


It was noted that the Santa Clara River Valley is unique in that is receives no Colorado river water and no Owens Valley water and is primarily served by ground water. A question was asked about development projects in the east end of the county such as Newhall Ranch’s Master Planned Community with respect to the river. Response: Such developments change the runoff dynamics. A faster runoff reduces the percolation time so that more water goes to the ocean. Slow runoff allows for more percolation so less water is lost to the ocean.

There are significant water reuse projects in Ventura county:  two desalination plants and a cross-county brine line. Oxnard has been working on a plant for advanced treatment of reclaimed water which should be on-line within this time period.  UWCD is looking to build a desalting facility for to pump brackish water from aquifers on the Oxnard plain for water already degraded by sea water intrusion. Calleguas Water District is building a “brine line” from Simi Valley to the Ocean, which is partially complete and could be used for the brine from the proposed brackish water desalter. To view the Calleguas Salinity Management plan click here. Agencies near the path of the brine line can connect for a fee if they plan to build their own desalination facilities.

There will be a workshop about the new California Sustainable Groundwater Act on April 1 in Fillmore, California.

Please be sure read the follow-on article about the workshop and the California Sustainable Groundwater Act.


Sheryl Hamlin: With an MS in Industrial Engineering, Sheryl Hamlin spent years in technology with stints at Motorola, Tandem Computers and various startups. She has been on the boards of neighborhood organizations both in San Francisco and Palm Springs where planning issues were her specialty. She now resides in Santa Paula and loves the historic fabric of the city.  Ms. Hamlin’s blog Stealth Fashion  and  technology product ‘ Plug and Play Webmaster’.

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2 Responses to Ventura County’s Freeman Diversion Dam

  1. Mark Thompson May 29, 2018 at 9:26 am

    Hi, can I fish off the damn for catfish?

  2. Citizen Reporter March 30, 2015 at 9:13 pm

    Very informative, thanks, Sheryl. Hopefully people will demand some common sense applied here.


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