Get Email Updates

Get Text Alerts

Sign up for recreational and commercial text alerts

Ladders and Licenses: Fish Passages Play Role in Relicensing Hydroelectric Facilities

By Bill McDavitt, Integrated Statistics, under contract to Greater Atlantic Regional Fisheries Office, Habitat Conservation Division

Hydroelectric facilities use the energy of river water spilling down the height of a dam to power turbines, which generate electricity. These facilities generally operate under a license from the Federal Energy Regulatory Commission (the Commission). These licenses typically last a long time—30 to 50 years. When licenses need to be renewed, we have an opportunity to review how the power plant operates, not just in terms of generating electricity but also in how it affects the environment. The Habitat Conservation Division works with these facilities to ensure that their operations are not harming diadromous fish and their habitats. Diadromous fish (river herring, shad, American eel) migrate between the ocean and rivers to complete their life cycles. In order for these fish to be successful, they have to pass safely upstream and downstream of these dams and turbines.

Fish lift in Lowell full of fish. Credit: Bill McDavitt/NOAA

Key Role in Ecosystem

Diadromous fish are prey for other commercially and recreationally important fish, such as striped bass, haddock, and lobster. The fish that pass these hydroelectric projects provide an important foundation not only for the freshwater river ecosystem, but also for estuary and ocean ecosystems. In addition, some of these fish are commercially important; for example, there is a commercial shad fishery in the lower reaches of the Connecticut River, and several alewife fisheries in Maine rivers supply bait for lobster fishermen.

Going with the Flow

The process of renewing a power plant license begins five years before an existing license expires. The Commission publishes information about a hydro facility’s operations, and at NOAA Fisheries, we review this information. If it isn’t clear that the facility is safe for fish, we ask for more information or ask the owner to determine whether the facility is in compliance with the Federal Power Act and the Magnuson Stevens Fishery Conservation and Management Act.

Figure 1 FERC Projects Currently Undergoing Relicensing (click to enlarge)

If a project operates a fish lift or fish ladder, two structures that move fish upstream of the dam, we ask for information about that structure and how it operates. We have a keen interest in data about water flow around dams, particularly through its turbines or powerhouse, through various gates, and through structures that help fish migrate upstream and downstream. We need this information because flow and the amount of water available for fish passage are critical for successful fish migration .

Once we have all the information we need, Section 18 of the Federal Power Act gives us authority to require changes to the project to improve fish passage. Sometimes we request minor improvements, but sometimes we request an entirely new fishway. We use this authority only at facilities where we know fish passed historically, and where we predict that the number of fish could significantly increase with new or improved passage.

Eight Projects in New England

Nationally, we have seen a dramatic increase in the number of facilities initiating the relicensing process since 2013. In the Greater Atlantic Region, we are currently working on relicensing eight hydroelectric projects (see Figure 1). At each one of these facilities, we are trying to increase the number of river herring, shad, sea lamprey, eel, and salmon that are able to migrate successfully past these projects on their way to and from spawning grounds.

Monitoring Returns

We also work closely with the hydroelectric power companies after a license has been issued to monitor the progress of fish passage at these facilities. For example, our efforts at two projects on the Merrimack River, at Lawrence and Lowell, have helped improve the number of returning river herring. State stocking efforts of herring have also helped improve the number of returning herring. As Figure 2 illustrates, with the combined efforts of improved passage and stocked fish, we have seen an encouraging increase in the number of herring passing through these projects in recent years. 

We look forward to seeing similar increases in these diadromous fish populations as they gain access to valuable habitat in New England rivers.  

Figure 2 Number of River Herring Counted at the Lawrence and Lowell Projects

Read more about how fish passages connect habitats and support coastal communities