A Dam Waste: Outdated Reservoir Rules Dump Water During Drought

February 13, 2015 | 1:51 pm
Juliet Christian-Smith
Western States Regional Director

Last year, California’s drought task force toured the parched state, visiting sites impacted by the record dry conditions. At Lake Mendocino, a reservoir located in the northern part of the state, they saw bathtub rings and beached docks, evidence of drastically reduced water levels. Therefore, it should be surprising that billions of gallons of water were released from the reservoir during the drought to comply with outdated flood control rules.


This blog is the second in a series on Climate-Water Disconnects, which profile key climate change planning failures related to water infrastructure.

Say what?

How did this happen? And why does it keep happening? While California is a leader when it comes to climate policy, the state is farther behind when it comes to incorporating climate science into water planning.

Bridges, reservoirs, hydroelectricity, streams, and rivers—all kinds of water projects are likely to be affected by warming temperatures. Yet water planners haven’t yet caught up to the scientists when it comes to ensuring water planning and operations are climate resilient.

Reservoirs are operated using old information

The U.S. Army Corps of Engineers (Corps) is responsible for monitoring and managing water levels for reservoirs that they own or operate, including several in California. The Corps follows reservoir release rules to ensure that water levels remain low enough to avoid any risk of flooding. Yet these rules were established decades ago at a time when weather forecasting capabilities were less advanced and the climate was different.

For example, the reservoir release rules for Lake Mendocino have not been updated since 1959. These rules require that any rainfall prior to November must be released in preparation for potential flooding—regardless of expected rainfall. The rules also allow only 68,000 acre-feet of water to be stored in the reservoir during the winter months, despite a capacity of over 110,000 acre-feet.

Lake Mendocino in 2014

Lake Mendocino in 2014. Photo: Sonoma County Water Agency

Some things have changed since 1959, including our understanding of weather patterns and climate change

In 1959, Alaska became a state, the Twilight Zone aired for the first time, and the average cost of a new house was around $12,000. Clearly, a few things have changed since then, including our scientific understanding of storms and climate change. Recently, the National Oceanic and Atmospheric Administration (NOAA) began collecting data from atmospheric river observatories along California’s coast. These observatories have enabled scientists to create models that reliably predict large storms 3-7 days before they reach California.

In addition, we have a better understanding of how climate change is affecting our water resources. A new study released yesterday warns of unprecedented drought risk this century:

“We have demonstrated that the mean state of drought in the late 21st century over the Central Plains and Southwest will likely exceed even the most severe mega-drought periods of the Medieval era in both high and moderate future [global warming] emissions scenarios, representing an unprecedented fundamental climate shift with respect to the last millennium.”

The study supports a growing body of evidence concluding that droughts will likely become longer and more frequent in the American West due to climate change. In a drier future, it will be critical to ensure that not a single drop of water is wasted.

As the California drought drags on, systemic change is needed now more than ever

Last year, U.S. Representative Jared Huffman proposed legislation that would have required the Corps to update its standards to incorporate modern climate science and weather forecasts into its reservoir rules: the Fixing Operations of Reservoirs to Encompass Climatic and Atmospheric Science Trends Act (FORECAST Act). The legislation would create flexibility within release standards by incorporating information from rolling five-day forecasts and ensuring the crucial water sources are not unnecessarily depleted during drought periods. Although last year’s bill died in committee, this week Representative Huffman reintroduced the FORECAST Act.

As the California drought drags on, it is time to revisit reservoir rules that were created decades ago in order to benefit from scientific advances and adapt to a drier future. Yesterday, the Corps agreed to a minor revision to its reservoir rules to allow Lake Mendocino to retain some of the recent rainfall after the driest January on record. Yet, the revision is small and temporary, highlighting the need for more comprehensive reform to bring reservoir management into twenty-first century. Not doing so would be a dam waste.

In future blog posts, I’ll share some other examples of the disconnection between what we know based on climate science and how we manage our water. There are serious risks throughout our water system and a lot more we could be doing to prepare for a changing climate in the West. Please check back over the coming weeks for more “say what?” stories.