Monday, August 20, 2012

Arundell Barranca - flood control or green infrastructure?

Ventura County Watershed Protection (formerly Flood Control) District is undergoing studies to address potential flooding impacts in the lower Arundell Barranca watershed.  According to hydraulic models, flood risk is higher than past FEMA models, with potential estimated 100-year flood damages of $62,170,700.  The District initially hoped to enlarge the concrete channel to accommodate the 100 year flows, and repair deterioration of Arundell Barranca Channel.

The diagram above shows the affected area - Arundell Barranca drains a large urban and agricultural area and discharges into the Ventura Harbor.

The diagram above illustrates the extent that the urban area has been channelized - compare this infrastructure with the historic condition in the 1945 aerial below.

The photo below shows the current state of the concrete in Arundell Barranca.  This channel conveys a constant flow of no less than 0.67 - 2 cfs in dry weather into the Ventura Harbor.  This amounts to up to 1400 acre feet per year of wasted water. If reused in some manner within the City of Ventura, this stormdrain discharge is sufficient volume to offset the proposed extraction at Saticoy Well #3.

During peak storm events, the channel conveys extremely high flows and tons of sediment into the harbor.  This sediment is periodically dredged and placed on nearby beaches.  Because of the direct hydrologic connection between urban, industrial, and agricultural runoff, these sediments and the water in the harbor contain high levels of toxins ranging from bacteria and metals to agricultural chemicals.

According to Watershed Protection District, the CEQA process has included:
  • Initial Study/Notice of Preparation Review : 1/20 – 2/18/2011
  • Scoping Meeting: 01/27/2011
  • Ventura Port District Board Meeting: 03/30/2011
  • Initial Study on line at:
  • EIR On Hold due to Public Comments Received
  • District Contracted with NHC for a Study to Quantify Baseline Condition and Further Investigate Existing Conditions and Potential Alternatives ($310,000 Contract)

Comments received included:
  • Increased Capacity = Increased Sediment & Harbor Dredging Costs
  • Increased Capacity = Increased Pollutants (Trash, Debris, Bacteria, Nitrates, Pesticides, etc.)
  • Project Should Provide Multiple Benefits
  • Coordinate with City of Ventura on Potential Treatment Wetlands Upstream of the SCR Estuary – Increases Grant Funding Eligibility
  • Redirect Channel to the Santa Clara River
  • Modify Outlet to Avoid Eddy at Stub Channel Confluence
  • Redirect Outlet to Avoid Damage to Boats, Docks, and Revetment
  • Build a Detention Basin on Farmland Instead

Next Steps:
  • Public Meeting to Present NHC Alternatives Study Results: July 19, 2012
  • Consider Public Comments and Feasibility, Narrow Down the Alternatives to Carry Forward in the EIR
  • Resume Preparation of the Draft EIR, to Include Additional Opportunities for Public Review and Comment
  • Draft EIR Public Meeting
  • Final EIR Board of Supervisors Hearing


The Surfrider Foundation has provided comments to this process, expressing concern that re-constructing the existing flood control channels to accommodate the 100-year storm flows will perpetuate a water quality problem that is in dire need of mitigation. We strongly recommend that alternatives be seriously considered in order to realize the opportunity for an integrated project that will mitigate flooding and improve water quality in the lower Santa Clara River watershed and Ventura Harbor.

The 2011 Water Quality Report provides a good overview of the water quality issues of concern. It is
noted that industrial discharges from Harris Water have ceased, but there is no indication of the volume of other industrial discharges into the barranca. Such discharges often have a negative short-term effect that is not captured in grab samples. For instance the recent spill reported in the news delivered hydrocarbon effluent to the harbor directly affecting summertime recreational uses (Spill near Ventura Harbor traced to barranca drain outlet -VCStar, Aug 1, 2012)

Industrial and agricultural discharges and spills also have a long term effect, as toxins accumulate in
sediments that are routinely dredged and discharged onto recreational beaches, as well as bioaccumulate in shellfish and other aquatic life which can negatively affect the productivity of the food chain and ultimately impact human health.  And repeated fish die-offs may be related to accumulated nutrient levels in the stagnant backwater channels in the harbor (most recently, Officials believe a lack of oxygen killed thousands of small fish Monday in the Ventura Harbor.
- April 18, 2011)

Therefore, although the report indicates that “a large fraction of the constituents were mostly above method reporting limits, but below regulatory objective levels,” this should not trivialize the seriousness of the discharge from Arundell Barranca.

There is a significant volume of water constantly flowing from this storm drain system, and an analysis of upstream sources should be conducted to determine opportunities for flow reduction and/or stormwater capture upstream of the project site, before flows reach Harbor Blvd. Various ‘green infrastructure’ approaches may be applicable within the urban watershed to mitigate both low and high flow volumes currently present in the concrete channel. Even modifying portions of the channel to include a soft bottom low flow channel may help reduce flows through infiltration.  We have previously presented a vision for such an 'urban retrofit' for the Sanjon Barranca in Ventura.


This is not a new problem, and in 1999 the City of Ventura was leading the charge on a creative approach to redirect flows away from the harbor and treat the water with a green infrastructure approach.

One proposal that has been circulated recently illustrates a vision for an Arundell Estuary Park, that would combine engineered treatment wetlands with public access and trails to beatify the area and solve the water quality problem in the harbor.

One thing is certain: a single purpose flood control project will perpetuate this problem for many decades to come.  Now is the time to develop a multi-purpose multi-agency solution to one of the most serious water quality problems on our coast.

More info:

Arundell Barranca Channel Improvements, Ventura County Watershed Protection District website,

Arundell Barranca Environmental Monitoring Final Report

City of San Buenaventura's May 1999 "Ventura Keys and Arundell Barranca Watershed Project Alternatives Report" (7.3MB, PDF)