Federal wildlife agencies continue to express concerns about how two giant water-diversion tunnels proposed in the Delta may harm imperiled species such as salmon and Delta smelt.
In letters made public last week, the U.S. Fish and Wildlife Service and National Marine Fisheries Service praised Gov. Jerry Brown's administration for making progress on many issues they raised last year in so-called "red flag letters."
But the agencies said the Bay Delta Conservation Plan still presents a number of major concerns. The letters respond to revised draft chapters of the plan released to the public over the past month.
The $14 billion proposal would divert a portion of the Sacramento River's flow into two 40-foot-diameter tunnels, fed by three new intakes on the Sacramento River near Courtland. It aims to balance potential harmful effects of the tunnels by restoring 100,000 acres of habitat to create a net benefit for wildlife.
Among the concerns expressed by the National Marine Fisheries Service is the potential that, in combination with climate change, the tunnels may cause extinction of winter-run chinook salmon, an endangered species in the Sacramento River.
The agency also said water diversions into the tunnels may, under some conditions, leave insufficient flow in the Sacramento River to permit fish migration – and may even reverse the river's flow in some situations.
Bay Delta Conservation Plan officials responded with their own letter, saying the plan would not make winter-run extinction more likely. It noted the National Marine Fisheries Service in 2009 said extinction would be likely with climate change alone unless upstream dams are modified for fish passage.
The U.S. Fish and Wildlife Service noted that the intakes, besides diverting water, also would divert as much as 9 percent of the river's sediment load. That could make Delta water clearer, but smelt actually need muddier water.
"Besides potentially negative effects on Delta smelt and longfin smelt and their habitat clearer water would encourage growth of exotic aquatic plants," the agency wrote.
The agencies cited a lack of evidence that the proposed habitat restoration would work and questioned whether there is enough suitable land to achieve the restoration goals.
"There is no specific analysis of the feasibility of acquiring 65,000 acres of land appropriate for tidally influenced habitat restoration," the National Marine Fisheries service wrote. "All related analyses proceed as if restoration will be wholly successful."
Karla Nemeth, program manager of the Bay Delta Conservation Plan, said she is "very optimistic" such concerns will be addressed in the final plan, set for release this summer.
The letters can be found online at: http://ht.ly/k5mk8.
Contact The Bee's Matt Weiser at (916) 321-1264. Follow him on Twitter @matt_weiser.