Setting Passage Performance Standards

It is not enough to simply build a fish passage structure. It has to be effective at moving fish across a barrier. For example, the fish ladder at the Brunswick dam was built almost 50 years ago and even though hundreds of thousands of fish arrive at its base, only a tiny fraction pass above the dam. Experts from MDMR and NOAA have studied necessary performance standards for fish passage and have recently published the following recommendations.

Safe, timely, and effective passage for diadromous species is often required for hydroelectric projects regulated by the Federal Energy Regulatory Commission (FERC). These measures may be unilaterally required by FERC or drafted by resource agencies pursuant to the Federal Power Act (Lake et al., 2024). Within the FERC licensing process, safe, timely, and effective is a qualitative metric, which does not identify clear, measurable standards for practitioners. However, resource management agencies can define specific fish passage performance standards that would be required to achieve predefined management objectives. This information could help hydropower practitioners define alternatives, including fishways and associated infrastructure or operational modifications or dam removal that would be necessary to achieve species- specific objectives.

The American Shad Alosa sapidissima is an anadromous fish species native to the east coast of North America. American Shad populations once supported valued commercial, recreational, subsistence, and sustenance fisheries but have collapsed across their range due largely to pollution, overexploitation, and reduced connectivity through dam construction. Fish passage facilities designed to resolve upstream passage issues have a history of low effectiveness for this species relative to design standards.

We investigated “Maine” and “Connecticut” hypothetical restoration scenarios, which were based on current real- world management objectives specified within the Penobscot, Kennebec, and Connecticut River management plans.

 Results: A range of performance standards were required to meet both hypothetical restoration scenarios, but in general, high upstream passage (>80%) and downstream survival (>75%) was required. 

BUT

Low upstream passage effectiveness has been documented for American Shad in Maine and elsewhere, with 0% passage being documented at the first dam on the Androscoggin River…