Dam removal continues to garner attention as a potential river restoration tool. The increasing possibility of dam removal through the FERC relicensing process, as well as through federal and state agency actions, makes a critical examination of the ecological benefits and costs essential. This paper reviews the possible ecological impacts of dam removal using various case studies. Restoration of an unregulated flow regime has resulted in increased biotic diversity through the enhancement of preferred spawning grounds or other habitat. By returning riverine conditions and sediment transport to formerly impounded areas, riffle/pool sequences, gravel, and cobble have reappeared, along with increases in biotic diversity. Fish passage has been another benefit of dam removal. However, the disappearance of the reservoir may also affect certain publicly desirable fisheries. Short-term ecological impacts of dam removal include an increased sediment load that may cause suffocation and abrasion to various biota and habitats. However, several recorded dam removals have suggested that the increased sediment load caused by removal should be a short-term effect. Pre-removal studies for contaminated sediment may be effective at controlling toxic release problems. Although monitoring and dam removal studies are limited, a continued examination of the possible ecological impacts is important for quantifying the resistance and resilience of aquatic ecosystems. Dam removal, although controversial, is an important alternative for river restoration.

Public Service Company of New Hampshire (PSNH) is a vertically integrated public utility that owns and operates nine hydroelectric projects in New Hampshire totaling approximately 70 MW. PSNH’s 1.1 MW Canaan Project is located on the upper Connecticut River in the states of New Hampshire and Vermont. The relicensing of this project was one of seven “pioneer” projects electing to utilize the Federal Energy Regulatory Commission’s (FERC or Commission) new Integrated Licensing Process (ILP) during the initial transition period.

During the ILP scoping process, resource agencies and intervenors requested that PSNH study the feasibility of upstream fish passage at the Canaan Project. There are no Atlantic salmon or other migratory fish in the project area: upstream fish passage was proposed for indigenous brook, and non-native brown and rainbow trout and other non-migratory resident fish. A standard Denil fishway and an Alaska Steeppass were determined to be technically feasible options and were evaluated for economic feasibility by PSNH’s consultant, Kleinschmidt Associates

A simulation model was created to identify dam operations and configurations that provided high survivals for Juvenile salmonids migrating out of the Snake River. Regional fisheries managers sought to identify ways to operate and configure the dams and the fish transportation system (barging) to provide safe passage conditions and survival rates that met or exceeded criteria set forth in the Biological Opinion. The challenge was to determine whether a candidate operation or construction item provided the expected survival benefits when the operations and configurations of the entire system were considered. The expected influence of candidate operations and configurations was simulated to screen many millions of combinations and identify the subset that met minimum criteria. Acceptable combinations exhibited a range of survival values, construction costs, and power revenues. This approach provided a set of cost effective combinations from which a mix of survival benefits, construction costs, and power revenues could be chosen to meet stewardship goals.

The Public Utility District No. 2 of Grant County, Washington (Grant PUD) owns and operates two hydroelectric projects on the Columbia River in Washington State: Wanapum Dam and Priest Rapids Dam - Priest Rapids Hydroelectric Project FERC License No. 2114. On May 3, 2004, the National Marine Fisheries Service (NMFS - then referred to as NOAA Fisheries) issued its Biological Opinion of the effects of the proposed action on listed species, in accordance with Section 7 of the Endangered Species Act of 1973 as amended (16 USC 1531 et seq.), regarding the Federal Energy Regulatory Commission’s (FERC’s) proposed action amending Grant PUD’s existing license for the Priest Rapids Hydroelectric Project (Project) to authorize implementation of an Interim Protection Plan for listed anadromous salmonids. Subsequent to NOAA Fisheries’ issuance of the Biological Opinion and consistent with the requirements of the Biological Opinion and within the scope of its own agency jurisdiction under the Federal Power Act, on December 16, 2004, FERC issued an Order requiring Grant PUD to “implement NOAA Fisheries’ Reasonable and Prudent Alternative (Actions 1 through 25) and sections 12.2 and 12.3 of NOAA Fisheries’ Biological Opinion filed with the Commission on May 6, 2004….”

In response to these requirements for downstream fish passage facilities, Grant PUD engaged in an extensive review of fish bypass concept designs to evaluate options available to increase the survival of smolts passing Wanapum Dam. Using a set of guiding principles related to the capture effectiveness, transport survival, construction costs, and construction feasibility of fish bypass options, the selection process resulted in the construction of the Wanapum Future Unit Fish Bypass (WFUFB) in early 2008. To evaluate fish responses to this newly-constructed fish bypass, in 2008 acoustically-tagged salmonid smolts were tracked as they approached and passed Wanapum Dam. The fish passage efficiency (FPE) and passage survival rate of three species of salmonid smolts that passed via the WFUFB were estimated.

Data analysis of the acoustically-tagged smolts showed a FPE of 57%, 34% and 31% for steelhead, sockeye and yearling Chinook (respectfully) and a passage survival estimate of 100%, 95% and 96% for steelhead, sockeye and yearling Chinook (respectfully).

This work, produced by John D. Echeverria  at Georgetown University Law Center, collects and describes the early cases that he and his research assistant Christine Faller have been able to locate involving takings and other constitutional challenges to laws requiring dam owners to install fishways to allow migratory fish to pass upstream and downstream.

A report submitted to the House Resources Committee, Subcommittee on Fisheries, Wildlife, and Oceans by the Office of Technology Assessment.

The focus of this report is technologies for fish passage around hydropower generation facilities and protection against entrainment and turbine mortality.Emphasis is given to Federal Energy Regulatory Commission (FERC)-licensed hydropower projects where fish protection is a subject of controversy and congressional interest due to the Federal Power Act (FPA) and the Electric Consumers Protection Act (ECPA). Thus institutional issues related to FERC-relicensing are also discussed. (Major points of controversy are highlighted in box 1-1.) Federal hydropower projects,especially in the Columbia River Basin, and irrigation water diversions in the Pacific Northwest and California are included to the extent that they provide information on fish passage technologies(see table 1-1). Many of the technologies discussed are applicable to other types of dams and water diversions. In fact, there are many more obstructions to fish passage that are not covered by FERC-licensing requirements, than are(approximately 76,000 dams versus 1,825 FERC-licensed facilities) (70).

The development of waterways, for hydropower and other industrial uses, has substantially altered many of the freshwater habitats of the planet and this has had considerable impact upon aquatic organisms. Industrial changes in aquatic ecosystems, including hydropower development, can restrict or delay fish migration, increase predation, affect water quantity and quality, and subject fish to direct damage and stress. This review will focus on the consequences for fish welfare and the progress towards developing the means to pass and protect fish at hydropower dams, at water withdrawal facilities, and in other engineered aquatic environments. It primarily concerns the large mainstem hydropower dams in the Columbia-Snake River Basin in the northwestern United States. Some methods for improving fish passage and protection at hydropower damsinvolve modifications and additions to engineered structures and occasionally use sensory stimuli such as light, sound, turbulence, or electric fields to influence fish distributions. Measures to improve fish survival, like spilling water at a dam to provide non-turbine passage, can cause other problems for fish, for example higher dissolved gas concentrations downstream. Reducing losses of fish in industrial environments is desirable in both the industrialized world, where many fish-related problems currently exist, and in the developing world, here lessons already learned may make future development more cost-effective and benign.