In the Southwest, three major reservoirs now sit closer to “dead pool” than any others in the country. A reservoir reaches dead pool when its water level falls so low that water can no longer flow downstream through the dam’s outlets. At that point, water deliveries can be disrupted and the dam may no longer be able to generate hydropower.

Elephant Butte Nears Empty

One of the most striking examples is Elephant Butte Reservoir, the largest reservoir in New Mexico. Located along the Rio Grande, the reservoir plays an important role in a region where water is already a precious resource.

As of mid-July 2026, Elephant Butte had fallen to just 2–3% of capacity. The consequences of such low water levels extend well beyond the reservoir itself. Elephant Butte provides irrigation water for hundreds of thousands of acres of farmland in New Mexico and Texas and supplies a portion of El Paso’s water.

Low reservoir levels can also affect recreation and local communities that depend on visitors coming to the lake. As shorelines retreat, boat ramps and marinas can become difficult or impossible to use, changing how people are able to access and enjoy the water.

Lake Powell and Lake Mead Remain Critically Low

Elephant Butte isn’t alone. Lake Powell and Lake Mead, two of the largest and best-known reservoirs in the United States, also remain at historically low levels.

Both are part of the Colorado River system, a water source relied upon by approximately 40 million people and more than five million acres of agricultural land.

In July, Lake Powell was at roughly 27% of capacity. Its water level was about 70 feet above the elevation at which Glen Canyon Dam would no longer be able to generate hydropower.

Farther downstream, Lake Mead was also around 27% full. The reservoir stores water used by communities, farms and businesses in Arizona, California, Nevada and Mexico, while Hoover Dam uses water released from Lake Mead to generate electricity.

Years of drought, combined with the enormous demand placed on the Colorado River, have left both reservoirs far below the levels they once routinely reached.

The Effects Reach Beyond the Southwest

Drought isn’t only a concern in the desert Southwest. This summer’s conditions across other parts of the country are another reminder of how closely our communities are tied to reliable water supplies.

Lower water levels can affect agriculture, drinking water, hydropower and recreation, but they can also change the waterways themselves. Reduced flows and shallower water can lead to warmer water temperatures and changes in water quality and aquatic habitat. Fish and other aquatic organisms may have less suitable habitat available, while recreational access can become more difficult.

Reservoirs are designed to capture water during wetter periods and make it available when conditions turn dry. But when drought continues year after year, even enormous reservoirs have limits.

The conditions at Elephant Butte, Lake Powell and Lake Mead offer a striking reminder that the health and availability of our water resources cannot be taken for granted. Whether it’s a massive reservoir in the Southwest or a lake or river closer to home, reliable water supplies are essential to communities, agriculture, recreation, wildlife and healthy aquatic ecosystems.

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At 5:12am on Wednesday, April 18, 1906 an earthquake of between 7.7 and 8.25 in magnitude struck San Francisco. Fires broke out and destroyed nearly 80% of the city as the already inadequate water supply failed. If San Francisco wanted to rebuild, it was apparent that a new source of water was badly needed.

Using the Hetch Hetchy’s Tuolumne River as a water source was proposed 50 years before the earthquake, but the devastation was enough to motivate government officials to authorize the development of the river. Wilderness conservation was at its early stages and to appease the arguments, permission was given to flood the valley under the condition that the power and water it provided could only be used for the public good, with no private profit derived.

The O’Shaughnessy Dam began construction in 1919 and was completed in 1923. Construction of the 137-mile pipeline that would eventually carry the Hetch Hetchy’s water to San Francisco was able to begin, as was the construction of hydroelectric power stations and the lines they would use to transmit that power to the city. Unfortunately, the city of San Francisco ran out of money to fund the project in 1925 – coincidentally as it reached Pacific Gas & Electric’s newly constructed substation, just across the San Francisco Bay.

Hetch Hetchy After Dam

PG&E announced that the company would temporarily take over the delivery of that power to the city, buying the power from it and selling it back to its citizens at a profit. Legal challenges to the situation began in 1941 and still continue today as it is believed PG&E continues to profit from Hetch Hetchy’s water and power.

This is one of the largest and most successful gravity-fed and power-generating municipal water supply systems in the world today and it was built amidst protest and the argument to remove the dam continues today.  The flooding of the valley has not been an environmental disaster as protesters had thought; it provides over 2 million San Francisco residents with clean water and generates 1.6 billion kilowatt hours of electricity annually.  Many argue that without the reservoir, the Hetch Hetchy would become overdeveloped and overcrowded just as the Yosemite Valley is now.