Dam removal and anadromous salmonid (Oncorhynchus spp.) conservation in California

Rebecca M Quiñones,Theodore E Grantham,Peter B Moyle,Brett N Harvey,Joseph D Kiernan,Alpa P Wintzer,Mick Klasson

doi:10.1007/s11160-014-9359-5

Abstract

Dam removal is often proposed for restoration of anadromous salmonid populations, which are in serious decline in California. However, the benefits of dam removal vary due to differences in affected populations and potential for environmental impacts. Here, we develop an assessment method to examine the relationship between dam removal and salmonid conservation, focusing on dams that act as complete migration barriers. Specifically, we (1) review the effects of dams on anadromous salmonids, (2) describe factors specific to dam removal in California, (3) propose a method to evaluate dam removal effects on salmonids, (4) apply this method to evaluate 24 dams, and (5) discuss potential effects of removing four dams on the Klamath River. Our flexible rating system can rapidly assess the likely effects of dam removal, as a first step in the prioritization of multiple dam removals. We rated eight dams proposed for removal and compared them with another 16 dams, which are not candidates for removal. Twelve of the 24 dams evaluated had scores that indicated at least a moderate benefit to salmonids following removal. In particular, scores indicated that removal of the four dams on the Klamath River is warranted for salmonid conservation. Ultimately, all dams will be abandoned, removed, or rebuilt even if the timespan is hundreds of years. Thus, periodic evaluation of the environmental benefits of dam removal is needed using criteria such as those presented in this paper.

Highlights

Dams are present in most California watersheds
Dam removal is often proposed for restoration of anadromous salmonid populations, which are in serious decline in California
The moderate benefits of removing Scott Dam were largely based on the number of salmonid taxa found in the Eel River (1a), the quantity (2c) of habitat upstream of the dam, and the few negative effects expected from dam removal (3b)

Summary

Introduction

Dams are present in most California watersheds. Whether constructed for flood control, irrigation, urban water use, or hydroelectric power generation, dams alter the movement of water, sediment, nutrients and organisms in riverine ecosystems (Magilligan andRev Fish Biol Fisheries (2015) 25:195–215 Species TaxaFederal/state listingStatus Impact from damsChinook salmon, Oncorhynchus tshawytschaSteelhead, Oncorhynchus mykissCoho salmon, Oncorhynchus kisutch Chum salmon, Oncorhynchus keta Pink salmon, Oncorhynchus gorbuscha Coastal cutthroat trout, Oncorhynchus clarki clarkiUpper Klamath-Trinity springUpper Klamath-Trinity fall. Dams are present in most California watersheds. Whether constructed for flood control, irrigation, urban water use, or hydroelectric power generation, dams alter the movement of water, sediment, nutrients and organisms in riverine ecosystems Rev Fish Biol Fisheries (2015) 25:195–215 Species Taxa. Oncorhynchus kisutch Chum salmon, Oncorhynchus keta Pink salmon, Oncorhynchus gorbuscha Coastal cutthroat trout, Oncorhynchus clarki clarki

Methods

Results

Conclusion