If You Build It, They Will Come – Essential Fish Habitat at Cosumnes Floodplain Mitigation Bank


Last weekend a friend and I took a kayak from the Cosumnes River Preserve, up the Lower Cosumnes River, and into the WES Cosumnes Floodplain Mitigation Bank.  Along the way we greeted fellow kayakers and stopped to chat with a couple fishermen on the bank of the river.  They had only been fishing a few hours, but had already caught several fish a piece.

“The fishing hasn’t been this good in a couple years,” they raved as we pulled the kayak away from shore.

“It must be the increase in essential fish habitat,” I called back and waved goodbye.

As we continued on our trip up the river and entered into the channel system of the Bank, I explained to my friend what I had meant by essential fish habitat (EFH).

It all started back in 1976 when Congress enacted the Magnuson–Stevens Fishery Conservation and Management Act (MFCMA), commonly referred to as the Magnuson–Stevens Act.  It is the primary law governing marine fisheries management in the United States.  EFH is defined in the Act as, those waters and substrates necessary to fish for spawning, breeding, feeding or growth to maturity.  The Act mandates that Federal action agencies must consult with National Marine Fisheries (NMFS) on any activity which they fund, permit, or carry out, that may adversely affect EFH. NMFS is required to provide EFH conservation and enhancement recommendations to the Federal action agencies.

Because Cosumnes Floodplain Mitigation Bank (Bank) is permitted by a Federal agency and the construction of the Bank may adversely affect EFH, NMFS was consulted.  NMFS found that the Cosumnes Floodplain Mitigation Bank would increase and improve the availability of quality habitat in the lower Cosumnes and Mokelumne rivers for fall-run Chinook salmon and Central Valley steelhead.  It was concluded that, while the Bank was found to have localized and seasonal effects on the hydrology, water quality, and fish community of these water bodies, it is not expected to have substantial adverse individual or population-level effects on anadromous salmonids – fall run Chinook salmon and Central Valley Steelhead.

To the contrary, the Bank is expected to benefit populations of salmon and steelhead by increasing the amount of floodplain rearing habitat in the lower reaches of these water bodies. The habitat provided by the Bank is anticipated to result in faster growth rates of juvenile salmonids that utilize the floodplain for short-term rearing, thereby increasing fitness and likelihood of survival and thus is considered essential fish habitat.

“With the Banks completion last summer and a glowing review from NMFS, it’s no wonder the fishing downstream is better this year,” my friend exclaimed.

“If you build it, they will come,” I said as I laughed and we started our journey back down the river.

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