By Patrick Shirey, AFS Resource Policy Committee Chair
The impact of dams on aquatic ecosystems and fisheries is well established. For dams that have reached the end of their usable life, or that no longer provide societal benefits that exceed their costs, dam removal is often a desired management outcome for safety, cost efficiency, and habitat improvement (O’Connor et al. 2015). Though the dam removals of large, decommissioned hydropower facilities on rivers like the Elwha in the state of Washington and the Penobscot in Maine tend to receive broad news coverage, many active programs exist to remove the tens of thousands of antiquated low‐head dams that impact headwater streams.
The National Inventory of Dams maintained by the U.S. Army Corps of Engineers (2018) identifies 91,468 total dams in the United States (> 6 feet in height) with an average age of 57 years. In addition, an estimated 2.41 million smaller dams in the United States less than 6 feet also impact fisheries with many not being under any agency jurisdiction (Brewitt and Colwyn 2020). Though Canada (over 15,000 dams; Canadian Dam Association 2019) and Mexico (over 5,000 dams and levees; National Water Commission 2017) have fewer, their policymakers are also facing aging dams and removal decisions. Dam removals per year are increasing in the USA with 97 removed in 2018, and 1,590 total dams removed through the end of 2018, according to the American Rivers database (2019).
As dam removals will continue, the AFS Resource Policy Committee (RPC) identified policy engagement on dam removal as a priority concern brought forth by AFS members. In addition, AFS identified hydroconnectivity for fish passage as a pressing issue in the Future of the Nation’s Fisheries and Aquatic Resources report (Pool 2017). Our members have a history of engaging on this issue to fulfill two of the AFS core constitution objectives: to promote fisheries conservation and to disseminate fisheries information. In 2004, the RPC completed a study report and policy statement on dam removal (Bigford 2004) that expired as official AFS policy in 2009, due to the 5‐year sunset clause in AFS bylaws (Bigford 2015). Nearly 1,000 dams have been removed in the United States since the previous policy statement was published (Figure 1A).
An update is also necessary because the knowledge from dam removal studies has increased over the last 15 years (Bellmore et al. 2017), giving a better understanding of how ecosystems respond (Bellmore et al. 2019). Of the 565 publications mentioning the topic “dam removal” since 1994 (Figure 1B), 64 publications (articles and reviews) have been published in fisheries‐focused journals with 40 of those published in AFS journals. All but 1 of these 40 were published after the previous policy statement (Bigford 2004).
Given this increase in knowledge, AFS can help make sure the fisheries knowledge of our membership informs future decision making. If you are a student studying these issues or a seasoned professional who has worked on the science and management of dam removals, I am asking for you to volunteer and help give us a breadth of experience that represents our membership. The RPC has recruited volunteers to help from the Estuaries Section (Karin Limburg), Bioengineering Section (Patrick O’Rourke), and Fish Habitat Section (Thomas Bigford).
Our goal is to craft a succinct, accessible statement, summarizing the state of fisheries knowledge pertaining to dam removal that can be used by our leadership to engage policymakers and inform decisions. Such a report could be used to improve decisions on individual dams or to establish priorities and a framework for programs that include dam removal. Policy engagement on dam removal is critical for AFS to ensure that policymakers consider scientific knowledge on aquatic connectivity, ecosystem resilience, and tradeoffs like invasive species, all in the face of climate change and extreme weather events. Unlike when the most recent AFS policy on dam removal was completed in 2004 with no particular audience in mind (Thomas Bigford, personal communication), the current effort would be well timed for strategic success for fisheries as additional end‐of‐life dams are considered for removal.
- American Rivers. 2019. American rivers dam removal database. figshare. Dataset. Available: https://doi.org/10.6084/m9.figshare.5234068.v6
- 2017. Status and trends of dam removal research in the United States. Wiley Interdisciplinary Reviews: Water 4( 2): e1164. , , , , , , and .
- 2019. Conceptualizing ecological responses to dam removal: if you remove it, what’s to come? BioScience 69: 26– 39. , , , , , , , , , , , , , , and .
- 2004. AFS draft study report and policy statement on dam removal. Fisheries 29( 7): 34– 35.
- 2015. Our renewed effort to make the most of science. Fisheries 40( 3): 96– 97.
- Brewitt, P. K., and 2020. Little dams, big problems: the legal and policy issues of nonjurisdictional dams. Wiley Interdisciplinary Reviews: Water 7( 1): e1393. Available: https://doi.org/10.1002/wat2.1393 .
- Canadian Dam Association. 2019. Dams in Canada. Ottawa. Available: https://www.cda.ca/EN/Dams_in_Canada
- National Water Commission. 2017. Statistics on water in Mexico. Mexico City. Available: https://www.gob.mx/conagua
- 2015. 1000 dams down and counting. Science 348: 496– 467. , , and .
- 2017. Future of the nation’s fisheries and aquatic resources: challenges we face in 2017 and beyond. Fisheries 42( 1): 4, 66.
- U.S. Army Corps of Engineers. 2018. National inventory of dams. Available: https://nid.sec.usace.army.mil/