DRAFT FINDING OF NO SIGNIFICANT IMPACT DWORSHAK LONG-TERM NUTRIENT SUPPLEMENTATION PROGRAM AHSAHKA, IDAHO JANUARY 2017

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1 DRAFT FINDING OF NO SIGNIFICANT IMPACT DWORSHAK LONG-TERM NUTRIENT SUPPLEMENTATION PROGRAM AHSAHKA, IDAHO JANUARY INTRODUCTION/PROPOSED ACTION The U.S. Army Corps of Engineers, Walla Walla District (Corps), proposes to implement a long-term nutrient supplementation program at the Dworshak Dam and Reservoir Project on River Mile 1.9 of the North Fork of the Clearwater River near Ahsahka, Idaho. This nutrient supplementation program would address biological productivity in the reservoir and assist with the management of certain undesirable bluegreen algae that adversely affect reservoir fisheries and interfere with public use of the The Corps has previously studied adding nutrients to Dworshak Reservoir to alter the food web. The Corps started a 5-year pilot study in 2007 in conjunction with the Idaho Department of Fish and Game (IDFG) to assess the feasibility of increasing the biological productivity of Dworshak Reservoir and abundance of edible phytoplankton 1 by adding inorganic liquid fertilizer (nitrogen). The Corps and IDFG agreed to suspend the pilot study in July 2010, then restarted the study in The continued pilot study ran from spring 2012 to fall Data collected through monitoring during this period indicated the effects of the nutrient supplementation were positive compared with data collected from the reservoir before the addition of the nitrogen. 2. PURPOSE AND NEED The purpose of the proposed long-term nutrient supplementation program is to enhance the biological productivity of Dworshak reservoir, primarily to improve the kokanee fishery, and to decrease the growth of undesirable blue-green algae. Any alternatives considered must not adversely affect water quality in the reservoir or operations of the two fish hatcheries downstream of the dam. The alternatives must also comply with applicable laws including the Endangered Species Act (ESA) and the current Biological Opinion for the operation for the Federal Columbia River Power System (FCRPS). The biological productivity enhancement is needed because of the low nutrient concentrations in the reservoir and the effects this has on the food web, including the fish populations, primarily kokanee. The enhancement would also address the periodic increases in certain blue-green algae species that can release toxins into the reservoir which may adversely affect the health of visitors, their pets, or other animals that drink the water. 1 Plankton are tiny aquatic organisms that form the base of the food web. They can be plant-like (phytoplankton) or animal-like (zooplankton). PM-EC a 1 January 2017

2 In the years immediately following the completion of Dworshak Dam, nutrients were plentiful within the reservoir because of the decomposition of organic matter on the thousands of acres that were inundated. The result was high biological productivity. However, this was a temporary situation and over time, Dworshak Reservoir productivity declined as a result of a loss of marine derived nutrients, nutrients being tied up in reservoir bottom sediments, and the low amount of nutrients flowing into the reservoir from the North Fork Clearwater River and its tributaries. Since its introduction into Dworshak Reservoir in 1972, kokanee salmon has become the primary fishery at the Because plankton is the main food source for kokanee, the amount of nutrients available in the reservoir becomes a critical factor in sustaining and growing this fishery as well as others. The decline in reservoir nutrients/productivity produced a corresponding decline in both the number and size of kokanee. In addition to effects on the kokanee fishery, current reservoir nutrient conditions have also affected phytoplankton species. The lack of sufficient nitrogen levels in the reservoir, especially towards late summer and fall, create conditions which promote the growth of inedible blue-green phytoplankton/algae. The blooms from two species of blue-green algae known to be present in the reservoir can present a public health risk (e.g. rash, illness) because of the toxins they may produce. The objectives of the nutrient supplementation program are to: provide a balanced nutrient loading for Dworshak Reservoir throughout the spring and summer improve the carbon flow within the reservoir, which may result in a change in the phytoplankton community that promotes an increase in more beneficial phytoplankton (which is consumed by zooplankton, a forage base for kokanee, rainbow trout, and smallmouth bass fry) and a reduction in the amount of inedible blue-green algae improve water quality by decreasing blue-green algae abundance, promote desirable phytoplankton and zooplankton, and improve late season water clarity improve the overall health and size structure of the kokanee population in the 3. ALTERNATIVES CONSIDERED The Corps considered five alternatives for enhancing the biological productivity of Dworshak Reservoir. These alternatives included different types of action including changing the reservoir operation and adding nutrients. The five alternatives are: Alternative 1 - No Action: Under this alternative, the Corps would operate the reservoir as it currently does to meet the authorized project purposes. The Corps would not implement any actions to enhance the biological productivity of the reservoir such as adjusting reservoir operations or adding nutrients to the PM-EC a 2 January 2017

3 Alternative 2 - Discontinue Reservoir Drawdown in Summer: Under this alternative the Corps would cease its current practice of drawing down Dworshak reservoir during the summer to improve passage conditions for Endangered Species Act-listed fish in the lower Snake River. If the Corps did not release the water, the reservoir level would remain at full pool during the growing season. This would allow riparian and wetland vegetation to grow along the shoreline and add nitrogen to the Alternative 3 - Mix Reservoir Sediments: Under this alternative the Corps would use an aerator or bubbler system to facilitate mixing of sediment and any associated nutrients from the bottom of the reservoir with the upper layers of the reservoir, thereby making nutrients available to phytoplankton. Alternative 4 Distribute Fish Carcasses: Under this alternative the Corps would distribute fish carcasses, or pellets made from ground and baked fish carcasses, around the reservoir to mimic the pre- Dworshak Dam conditions when adult steelhead returned to the North Fork Clearwater to spawn and die. Their spawned out carcasses provided a source of nutrients including trace nutrients derived from the ocean. Alternative 5 Continue Applying Liquid Fertilizer (Proposed Alternative): Under Alternative 5 the Corps would continue to apply inorganic liquid fertilizer (nitrogen) to Dworshak Reservoir as performed under the two pilot studies. The Corps would continue to monitor the effects of the program on water quality and biological productivity in the Based on the results of the monitoring that would continue to be done, the Corps would use adaptive management to make adjustments to the program as needed. Alternative 1, the No Action alternative, does not meet the purpose and need as it does not address the need to enhance productivity in the reservoir, but was carried forward as required by NEPA to set the baseline from which to compare all other alternatives. Alternative 2 would not comply with the National Marine Fisheries Service (NMFS) Biological Opinion and was not carried forward. Alternative 3 would adversely affect water quality in the reservoir and was not carried forward. Alternative 4 has the potential to introduce disease into the downstream fish hatcheries and was not carried forward. Alternative 5 was the only alternative that met the criteria and was therefore carried forward for evaluation. 4. ENVIRONMENTAL EFFECTS The Proposed Action Alternative and the No Action Alternative were analyzed for potential effects to the following resources: Water Quality, Fisheries, Threatened and Endangered Species, and Recreation. This analysis is detailed in Section 3 of the EA. The analysis concluded there would be no adverse effects to any of the resources from the Proposed Alternative, and overall long-term effects on all analyzed resources would be insignificant or beneficial. The primary benefits of the nutrient supplementation program would be an increase in primary productivity, a reduction in the percentage of the algal population that is composed of the blue-greens, an increase in the edible forms of algae, and an increase in zooplankton biomass. Kokanee populations could PM-EC a 3 January 2017

4 still fluctuate under the Proposed Alternative, but they are likely to have adequate zooplankton to feed on and grow to a catchable size. The number of reservoir visitors participating in fishing or boating may increase if the number and/or size of kokanee, smallmouth bass, or rainbow trout increase because of the nutrient supplementation. Swimmers may experience fewer blue-green algal blooms as the additional nutrients are expected to help keep blue-green algae populations low. The potential effects of the proposed action, when combined with the effects of past, present and reasonably foreseeable future actions, is not expected to result in significant effects to the resources identified above. 5. PUBLIC COMMENT/INVOLVEMENT Agency and public involvement regarding nutrient supplementation in the Reservoir have been ongoing since the original pilot study started in The Corps distributed an EA and FONSI for public review in The EPA received public comments in 2011 on its proposal to issue a National Pollutant Discharge Elimination System (NPDES) permit to the Corps for the pilot study. The Corps made this EA and draft FONSI available to individuals, businesses, organizations and agencies for a 30-day review and comment period from January xx, 2017 February xx, The District received xxxxx comment documents from interested members of the public. (Dates and numbers to be filled in for the Final FONSI.) (A summary of the comments received will be included in the Final FONSI). 6. COMPLIANCE WITH OTHER LAWS AND REGULATIONS Section 4 of the EA provides a discussion of compliance with other laws and regulations. The proposed action complies with other federal laws and applicable regulations. The Corps received a Clean Water Act NPDES permit from the Environmental Protection Agency (EPA) in 2011 for the pilot study. EPA has administratively extended this permit indefinitely. Idaho Department of Environmental Quality issued Clean Water Section 401 Water Quality Certification for the NPDES permit in Endangered Species Act consultation was completed twice as part of the pilot studies. The Corps received concurrence with its not likely to adversely affect determination from U.S. Fish and Wildlife Service (USFWS) and NMFS in The Corps and EPA received concurrence from USFWS and NMFS in 2011 for the issuance of the NPDES permit. The Corps notified the USFWS and NMFS it was proposing to indefinitely continue the annual nutrient supplementation program, consistent with the 2006 and 2011 consultations. The Corps stated it did not anticipate any adverse effects to listed species in the future from the program. In their responses dated January 19, PM-EC a 4 January 2017

5 2017 and January 23, 2017, respectively, USFWS and NMFS concurred continuation of the program would not have any effects to listed fish or critical habitat not considered in the two consultations and their previous concurrence with the Corps determination of affect to ESA-listed species remained in effect. The Corps completed compliance with the National Historic Preservation Act for the nutrient supplementation pilot study in 2011 when it performed a cultural resources assessment and made a determination of No Potential to Affect Historic Properties. The Corps confirmed this determination would also apply to an indefinite continuation of the supplementation program. 7. CONCLUSION/FINDING Having reviewed the Dworshak Long-Term Nutrient Supplementation Program EA, I find the document provides sufficient discussions on the purpose and need for the proposed action, alternatives, the environmental effects of the proposed action and alternatives, and a listing of agencies and persons consulted. I have taken into consideration the technical aspects of the project, best scientific information available and public comments received. These documents provide sufficient evidence and analysis to meet the District s requirements pursuant to the National Environmental Policy Act. Based on this information, I find that implementation of the proposed action would not result in significant impacts on the quality of the human environment and that an environmental impact statement is not required. The District will implement Alternative 5 (Continue Applying Liquid Fertilizer-Preferred Alternative) at the earliest opportunity, subject to availability of funding and competing Project priorities. Damon A. Delarosa Lieutenant Colonel, Corps of Engineers District Commander Date PM-EC a 5 January 2017