Monday, December 10, 2007

Ventura Wastewater Treatment Plant

Anyone who surfs or swims near the mouth of the Santa Clara River knows that there is something going on with the beach water quality. Although the estuary receives water from numerous upstream sources, the primary source during normal/dry weather is the Ventura Wastewater Treatment Plant.

Last week the Regional Water Quality Control Board (RWQCB) heard comments on a proposal to slowly phase out the discharge of treated sewage into the Santa Clara River estuary. The City of Ventura currently discharges over 8 million gallons a day, the last direct estuary discharge in the state. There is a lack of agreement on the effects of this, positive and negative. The Ventura County Star published a good summary of the issues.

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The aerial view on this map shows the existing treatment ponds that help clean the water before it flows into the estuary. In this image the sand berm at the beach is open and the river is flowing into the ocean.

One of the primary issues triggering the need to re-evaluate the discharge was the concentration of copper in the effluent. Copper is toxic to fish and wildlife, and originates from copper pipes in all the homes that flush into the sewer system. The discharge exceeded the toxicity limits for salt water species, many of which rely on estuary habitat for reproduction.
The RWQCB has also listed the 49 acre estuary for high levels of Coliform Bacteria, as well as agricultural chemicals. (Another new area of concern is the concentrations of pharmaceuticals in wastewater.) And although the city commissioned a study last year that highlighted the benefits of the discharge, this document did not mention the effects of nutrients, which can feed algae blooms which can lead to eutrophication (oxygen depletion in the water which can kill fish.)

Other impacts occur due to the unnatural volume of water that backs up in the estuary when the beach berm closes the rivermouth, which is most of the year. Apart from the fact that areas of McGrath State Beach flood as the water level rises, the stagnant nutrient-rich water tends to get fairly nasty before it flushes out when the berm breaches - directly onto the beach and into the lineup.

INTEGRATED SOLUTIONS: Oftentimes, solutions to a problem like this are considered in isolation from the broader regional issues. Although the city is planning to study the costs of an ocean outfall or moving the discharge point up the river, other alternatives may be possible. For instance, water conservation measures could reduce the volume of "waste" water arriving at the treatment plant. Considering that more than half of the "waste" has been used only once in a bathtub or shower, greywater systems would help reduce inflow at the plant, while also making better use of our limited water supply. (Landscaping irrigation uses a large percentage of the potable water supply.) Other integrated solutions may include strategically located "satellite" treatment plants that would provide reclaimed water to parks and other municipal facilities.