Aquatic Invertebrate Dam Removal Monitoring

A primary uncertainty concerning the removal of four dams on the Klamath River is how such actions will affect native biota, including salmon stocks. Dam removal is expected to mobilize millions of cubic yards of stored sediment, functionally shifting river dynamics and changing channel morphology. Removal of the dams will also force biota from reservoirs and enable them to invade the riverine environment. Such changes will elicit a strong biological response. In order to understand the impact and subsequent recovery of native species, before- and after-dam removal studies are necessary. Quantifying changes to river biota through time is critical to inform adaptive management and define the response trajectory of the Klamath River post dam removal. Quantifying the response of dam removal and communicating how the river is changing to tribal members, local constituents, stakeholders, rural communities, and those contemplating dam removal in other river systems is fundamental to measuring dam removal success.

The primary goal of this project is to determine the species composition and relative abundance of macroinvertebrates in the Klamath River. It is anticipated that after dam removal, this study could be repeated and the results compared to previous data collections. Our specific objectives for this task are to quantify the relative amount and types of benthic organisms over time and space for mainstem Klamath River environments and analyze the data and make it available for use in determining effects of management actions such as dam removal, and to refine future management actions.



In order to achieve project outcomes, we propose to collect macroinvertebrate relative abundance data from the bed (benthos) of the river. This data will be collected four times per year at approximately ten different study locations. The exact locations of study sites will be chosen based on their geographic locations and accessibility. Sampling sites will be more numerous in the first ten miles downstream of Iron Gate Dam as this is where we expect the greatest amount of habitat change to occur. If this project continues after dam removal, additional sampling sites may be established in the newly formed river channel within the reservoir reach, or in geographically associated tributaries.



Macroinvertebrate benthic samples will be collected using a kick net with a mesh size of 500 µm and a one by one-foot sampling square. All rocks within this square will be rubbed for 60 seconds, with the invertebrates floating into the kick net. Macroinvertebrate samples will be preserved in bottles using a 90% ethanol solution for later processing. Sample processing will be conducted by the Center for Watershed Sciences at the University of California, Davis (or other qualified contractor) and this project will allow the YTFP to process any previous collections made related to this study. All samples will be quantified and have a taxonomic breakdown provided for the invertebrates contained in the collections.

Project Objective: Klamath River salmon stocks have declined significantly from historical levels and the recovery of Klamath River Basin salmon populations is a priority for federal, state, and tribal governments. Although the decline of salmon in the Klamath River system is complex, the primary cause is the presence of the Klamath River Hydroelectric Project. Direct habitat alterations caused by this project include lack of fish passage, interruption of sediment routing, streambed alteration, shifting nutrient and water quality dynamics, and changes to the natural hydrograph and thermal regimes. These changes have shifted the physical environment, impeded fish passage, increased fish disease, degraded water quality, facilitated the invasion of non-native fishes, and precipitated a strong decline in native salmon stocks.

Following nearly 20-years of effort by Klamath Basin tribes, Federal Agencies, State Agencies, NGO’s, and numerous other partners, the Klamath River Dams are on a trajectory to be removed in 2023 or 2024. To the best of our knowledge, this will be the largest dam removal project ever implemented. Assessing the effects of the removal is critical to those interested in the health of the Klamath Basin and of global interest to those contemplating large-scale dam removal projects. We (the Yurok Tribal Fisheries Department) are proposing to continue our previously funded work to evaluate the effects of dam removal on the ecosystem by monitoring changes to the aquatic invertebrate communities of the Klamath River.



We are facing a unique opportunity to continue collecting baseline information regarding conditions in the Klamath River prior to dam removal and during the subsequent recovery of the Klamath River ecosystem. Some physical baseline information has been collected to create an elevational model of the Klamath River above the hydroelectric project to the mouth of the Klamath River. However, little attention has been dedicated to assessing biological conditions of the Klamath River prior to dam removal. This study proposes to help fill this data gap, so that we have a solid assessment of biological conditions prior to (and during) dam removal and can quantify ecosystem response. The primary objective of this study is to collect monitoring data in the form of aquatic invertebrate samples. This data and subsequent analysis is extremely important to the overall understanding of the ecosystem prior to, and during dam removal, as it allows us to account for inter-annual variations in the riverine biota.Project Benefit: The benefit of this project will be shown through the high-quality data that we plan to collect. This data set will be extremely important to researchers and river managers before, during and after dam removal is complete. Information gathered during this venture will help inform adaptive management, fish re-population efforts and river restoration projects. Data from these invertebrate collections can inform researchers and river managers of baseline riverine conditions before and during dam removal.



An extremely important measure of the project’s success will occur after dam removal is complete. River managers will be closely monitoring how fish (especially salmonids) are responding to the changes that come with dam removal. It is imperative that biological data from the pre-dam removal period exists in order to make assumptions regarding the response of Klamath River fish stocks. For example, if SONCC ESU Coho Salmon populations seem to be suffering after dam removal, this baseline data set can help to ascertain whether the food web has recovered or if the problem lies elsewhere. Priority 2