Wednesday, September 22, 2010

Estuary breach kills fish

It happens several times a year. The Santa Clara River estuary fills beyond capacity and finally bursts. When the sand berm breaches, the wetland rapidly drains, and thousands of fish are left high and dry.

Last Thursday night the estuary drained rapidly. The timing was right, because Friday morning was scheduled for biologist surveys as part of ongoing studies for the City of Ventura's wastewater treatment plant. The photos here document six of the juvenile steelhead found stranded in the estuary.

Although this may appear to be a natural occurrence, this is a highly altered ecosystem. Upstream dams and wells reduce the Santa Clara to a dry riverbed during the summer and fall, while the Ventura wastewater plant delivers millions of gallons a day of treated effluent directly into the estuary. Under natural circumstances the estuary would reach an equilibrium until the first big rains flush down the river and breach the berm from above, opening the system to the Pacific ocean. But these days it slowly fills beyond capacity, and like a balloon it eventually pops. Humans often help this happen by digging small canals in the sand berm, but large swells and tides accomplish the same end.

The result is a huge flush of nutrient-rich water onto the beach, and the death of federally listed species such as steelhead and the tidewater goby. Ironically, it is these two species that have been pitted against each other in the ongoing debate over the management of this estuary.

Two separate federal agencies are charged with stewarding the fish - NOAA Fisheries for the steelhead trout, and Fish and Wildlife Service over the tidewater goby. Past decisions have been based upon the need for continued water for the tidewater goby, based upon the fear that reduced flows from the wastewater plant would limit habitat in the estuary. And although steelhead often struggle to get downstream with limited flows past migration barriers, studies have revealed that steelhead rely upon the estuary in order to grow to a size which ensures their survival once they enter the ocean.

The fish in these photos had grown much larger than they would have in the small freshwater streams. Had the lagoon breached later in the year from high flows in the river, these fish would have successfully entered the ocean with a high probability of returning to spawn in the future.

Santa Clara River Estuary Special Studies

Next Stakeholder meeting; Sept. 28, 2010 from 10 am - Noon
Ventura Water Reclamation Facility
1400 Spinnaker Drive, Ventura

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