In my first article regarding the state’s Delta Conveyance Project, I provided some background on the initiative and introduced that there are some important design changes we should be fighting for as advocates of the Delta.

The first change I introduced is the need for any design to incorporate the project’s ability to deliver fresh water to the South Delta as necessary to support wildlife and better water quality conditions.

State Department of Water Resources (DWR) and the Design and Construction Authority (DCA) leaders have been open and helpful by giving me access to experts within their organizations.

The experts have indicated that if multiple islands flooded in the South Delta and salt water was rushing in, as might be the case in an earthquake or terrorism situation, having a source of fresh water in the South Delta could help reduce salinity intrusion initially, but more importantly, could be valuable in flushing salinity out of the South Delta after a problem.

A 6000 CFS source of water right in the South Delta would greatly improve the flushing out of salt, which would reduce the length of time during which water is unusable by farmers or exporters.

Of course, more analysis is needed, but this capability seems pretty logical and important to me. Once in place, a system to improve water quality in the South Delta could also be used operationally to better fight algae issues and support fish and wildlife.

This concept is so logical that it was actually included in the original design of the Peripheral Canal that was shot down in the 1970s. This is amazing! So this idea is not new.

Included in the design of the ‘70s was an ability to refresh the Delta at spots where the canal intersected Delta waterways, and deliver up to 6300 CFS of water to the Delta.

The designers back in the ‘70s knew that their design might reverse flows in the Delta, where pumps are pulling water out of the Delta. The reverse flows confuse fish and disrupt migratory patterns. The benefits of refreshing flows are discussed in the environmental impact report for the 1970s project, including the benefit of helping prevent the strong reverse flows that have been a problem with the current through delta conveyance.

The recently proposed tunnel conveyance has a design capacity of only 6000 CFS in total, much less than the canal, so it could not support the level of refresh flows listed for the canal project. However, the fact that the design from the ‘70s shows that using a conveyance to improve water quality and emergency response in the delta is logical and actually has been analyzed in depth before.

Any new tunnel design should have some capacity to benefit the delta with refreshing flows especially in emergency situations.

David Gloski

Bethel Island

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