Floyd Dominy, the commissioner of the federal Bureau of Reclamation during the 1960s, spearheaded the construction of Glen Canyon Dam on the Colorado River. While the dam’s completion in 1963 marked a monumental engineering feat, it could not have anticipated the profound climate shifts occurring today, characterized by dwindling snowpack, soaring temperatures, and persistently low water levels in Lake Powell. However, Dominy and his team possessed the foresight to recognize, and arguably should have acted upon, the inherent design limitations of the dam that would leave little operational flexibility in the face of a severe water supply crisis impacting the river and its vast watershed.

A crisis on the Colorado River has been steadily escalating for decades, exacerbated by ongoing disputes among the entities claiming rights to its rapidly diminishing flows. This situation has now entered a critical and precarious phase. A significant deadline passed on November 11th, when the seven Basin states—California, Arizona, Nevada, Utah, New Mexico, Colorado, and Wyoming—were expected to agree on a new water management plan, failing which the federal government would be compelled to impose its own, a scenario universally undesirable. Concurrently, the 30 Native American tribes holding water rights on the river have historically been excluded from these crucial negotiations, a continued oversight that perpetuates historical inequities.

The November deadline was extended, with the federal government deferring a decision until February 14th, a move that surprised few, as unmet deadlines and unfulfilled ultimatums have become routine on the Colorado River. Decades of declining reservoir levels and clear scientific warnings about global warming and persistent drought have prompted considerable concern and some temporary conservation measures, yet a fundamental shift in water usage patterns within the Colorado River Basin remains elusive.

For years, the seven Basin states have been drawing more water than the river naturally supplies, accessing reserves from the surpluses accumulated in reservoirs like Lake Mead and Lake Powell during the wetter periods of the 1980s and 1990s. This practice relied on water entitlements established in 1922 under the Colorado River Compact, which were based on an overestimation of the river’s flow. Consequently, the allocated water rights, often referred to as "paper water," have proven to be largely fictional and a perpetual source of conflict. This critical "savings account" has now been depleted, with both Lake Mead and Lake Powell operating at less than 30% capacity, and the trend indicates a steady decline. The accelerating impacts of global warming have further exacerbated this situation; since the turn of the century, the river’s flow has decreased by approximately 20% below its long-term annual averages, with scientific projections indicating a continued downward trend as the climate warms.

Meanwhile, the physical infrastructure designed to manage the Colorado River’s water is itself on the precipice of a significant and potentially catastrophic crisis. This critical issue has received minimal acknowledgement from the Bureau of Reclamation, with the exception of a brief mention in a technical memorandum released in 2024. The declining water levels in the reservoirs are exposing deeper operational challenges within Glen Canyon Dam, the colossal structure that impounds Lake Powell. The 710-foot-tall dam was engineered for a stable hydrological environment, a stark contrast to the inherent variability of the Colorado River, which is renowned for its extreme fluctuations, including devastating floods and prolonged droughts. Despite this known characteristic, the Bureau of Reclamation, perhaps emboldened by Cold War confidence or overconfidence, downplayed the potential risks. During the exceptionally wet winter of 1983, an El Niño event, the dam narrowly avoided disaster due to a combination of mismanagement and its design limitations, specifically its insufficient spillway capacity to handle major floods. It was only through emergency measures, including the temporary installation of plywood across the dam’s crest and a fortunate slowdown in snowmelt due to cooler temperatures, that Glen Canyon Dam was saved from overtopping.

Today, the dam faces a different, yet equally perilous, threat: a scarcity of water. By March 2023, the water level in Lake Powell had receded to within 30 feet of the "minimum power pool," the critical threshold below which hydropower generation ceases. At 3,490 feet above sea level, this level is only 20 feet above the generators’ intakes, known as penstocks. However, the dam’s eight turbines must be shut down at minimum power pool to prevent cavitation, a phenomenon where air is drawn into the penstocks, creating explosive bubbles that can lead to severe damage within the dam’s structure.

The implications of reaching minimum power pool are profoundly concerning. Once the penstocks are closed, the only remaining method for releasing water through the dam involves the river outlet works (ROWs). These consist of two intakes on the rear face of the dam, feeding into four 96-inch-diameter steel pipes with a combined maximum discharge capacity of 15,000 cubic feet per second. However, these ROWs, also referred to as bypass tubes, suffer from a significant design flaw: they are not engineered for prolonged use and are susceptible to erosion when reservoir levels are low.

In 2023, during a high-flow release into the Grand Canyon conducted at low reservoir levels, damaging cavitation was observed within the ROWs. The Bureau has cautioned that extended use would likely lead to further cavitation. In practice, the safe release of water downstream may be significantly less than their stated capacity, and any onset of cavitation could necessitate a complete shutdown of flows. Such a scenario would render the dam incapable of meeting its legal obligations for downstream water delivery. This means that the 25 million people downstream who rely on the Colorado River, as well as the multi-billion-dollar agricultural sector, could face severe water shortages. Consequently, Lake Powell, and by extension the entire Colorado River system, stands precariously close to operational failure.

Should the reservoir levels drop to the elevation of the ROW intakes, approximately 3,370 feet above sea level, Lake Powell would reach "dead pool." At this point, water would only pass through the dam when the river’s inflow exceeded the amount lost to evaporation from the reservoir. There are no further intakes or spillways situated below the ROWs. Critically, there is no "drain plug" to release the remaining water. However, a substantial volume of water—approximately 1.7 million acre-feet—would remain impounded behind the dam, becoming stagnant and susceptible to heating, algal blooms, and potentially lethal anoxic conditions. Due to the distinctive martini-glass shape of Lake Powell’s vertical cross-section, the water level could fluctuate dramatically, potentially by as much as 100 feet within a single season.

The absence or severe restriction of water flow through Glen Canyon Dam would trigger a disaster of unparalleled proportions. This would profoundly impact major population centers, some of the world’s most significant economies, and the fragile ecosystems stretching from the river’s headwaters to the Gulf of California in Mexico. The Lower Basin states of California, Arizona, and Nevada articulated these concerns in a recent letter to Interior Secretary Doug Burgum, arguing that the Bureau’s omission of the dam’s plumbing issues in its current environmental impact statement for post-2026 operations violates federal law. The letter emphasized, "Addressing the infrastructure limitations may be the one long-term measure that would best achieve operation and management improvements to the Glen Canyon Dam."

To date, the Bureau has not issued a formal response to these critical concerns.

It is evident that modifications to Glen Canyon Dam are imperative to ensure its continued legal and operational viability. In this process, the ecological health of Glen Canyon, upstream of the dam, and the Grand Canyon, downstream, must be a paramount consideration. The most effective strategy to avert operational failure and the attendant economic and ecological catastrophes is to re-engineer the dam to allow for the passage of the river at its natural level, facilitating the transport of sediment into the Grand Canyon.

Fortuitously, Floyd Dominy himself conceived a straightforward yet ingenious solution. In 1997, the former commissioner sketched a proposal on a cocktail napkin illustrating the potential for new bypass tunnels to be excavated through the soft sandstone surrounding the dam. These tunnels would be equipped with waterproof valves to regulate both water and sediment flow. This concept essentially proposes treating the Colorado River, now critically ill, with a form of open-heart surgery—a full bypass. Dominy’s napkin sketch, signed and presented to Richard Ingebretsen, founder of the Glen Canyon Institute, serves as a visionary blueprint for a more sustainable future for the Colorado River and the myriad life forms and human communities that depend upon it.

However, the window of opportunity to avoid dead pool is alarmingly narrow and rapidly closing, particularly given the extensive time required for governmental study, design, and implementation of any corrective measures. The degradation of federal agency expertise and capacity during the Trump administration further amplifies the urgency of this issue. Regardless of the decisions made on February 14th, federal authorities and the Basin states must transcend the ongoing "water wars" and proactively focus on constructing a resilient and sustainable future for the Colorado River.