Rivers across the West are managed by large dams, many of them built and operated by federal agencies. Most of those dams were built in the middle third of the 20th Century, during a period when Congress seemingly believed that the answer to nearly any water problem was a new dam. By the time the “big dam era” came to an end around 1980, the government had built well over a thousand dams nationally. Congress authorized each dam to serve particular purposes: water supply (especially for irrigation) was the primary purpose of most Bureau of Reclamation dams, whereas flood control was the main mission of most Corps of Engineers dams. Both agencies would eventually build many “multi-purpose” facilities, serving purposes such as hydropower generation, reservoir recreation, and downstream flow regulation.
Most federal dams are now at least 40 years old, and the West has changed a lot since they were new, in several ways that should influence water management. For example, water demands have changed with population growth and economic shifts; science has improved our understanding of the impacts of dam operations; and environmental and recreational amenities have grown in importance in many parts of the region. In addition, climate change is already raising temperatures, changing the form and timing of precipitation, and altering historically “normal” runoff patterns. All of these changes seem likely to continue as we move deeper into the 21st Century, and all of them have implications for the operation of federal dams in the West.
Neither of the major federal dam-operating agencies, however, has a program of reviewing and revising the operating plans for its reservoirs. While the Corps’ rules on “water control manuals” call for reviewing them every ten years, and the Bureau has launched a “reservoir operations pilot initiative” to evaluate potential changes at a few select projects, neither has made a practice of reviewing its established operating plans. Congress has shown increasing interest in this issue, however, pushing the agencies (especially the Corps) to move ahead with operating plan reviews. For my part, I have made the case for both the Corps and the Bureau to review the long-term operating plans for their projects, considering a range of alternatives and engaging the public in the process. (Before clicking the link on my forthcoming article — reviewingresopspdf — be warned that the piece is long, even by the standards of committed water wonks.)
The good news is that one major federal dam, the Bureau’s Glen Canyon Dam on the Colorado River, will soon have a new operating plan. Glen Canyon was built in the 1960s as a major storage project for the Colorado River Basin; it also generates lots of hydropower and forms the popular Lake Powell. But downstream impacts of dam operations led Congress to pass the Grand Canyon Protection Act in 1992, and the Bureau followed with a new operating plan for Glen Canyon Dam that reduced some of those impacts. The new Long-Term Experimental and Management Plan (LTEMP) updates that earlier plan, and incorporates science that has developed over the past two decades. But it certainly does not re-purpose Glen Canyon Dam; to the contrary, LTEMP must remain consistent with two interstate compacts, multiple statutes, a treaty with Mexico, a major Supreme Court case, a series of administrative decisions on dam operations, etc.
In developing the LTEMP, the Bureau and the National Park Service worked with over a dozen cooperating agencies, and considered a wide range of potential effects of various operating scenarios. I cannot say whether the final LTEMP the agencies selected represents the best possible plan for operating Glen Canyon Dam, in light of all the values and interests involved. What I like about LTEMP is that the federal government engaged scientists, stakeholders, and the interested public; considered a range of alternative operating regimes; tested how those alternatives would perform in over a dozen different categories; and selected the alternative that the agencies regarded as the best overall for the environment. As the West continues to change, the federal government should undertake this kind of review for more of its old water projects, helping ensure that 20th century dams can adapt to 21st century needs.