California water management made little ‘progress’ on climate change

The state agency that manages California’s water resources has made “only limited progress” in accounting for the effects of climate change on its operations and forecasts, a state audit found this week.

“Until further progress is made, the Department of Water Resources will be less prepared than it could be to effectively manage the State’s water resources in the face of more extreme weather conditions,” the state audit concluded.

The Department of Water Resources also sometimes releases water from its surface reservoirs without sufficient explanation and documentation, the state auditor reported, citing the Lake Oroville releases as an example.

Some water discharges are necessary to maintain water quality and support habitats for fish and wildlife species, but the agency released more water than required, water that could have been used by up to 229,000 households in one year, he wrote. the state auditor.

Former Assemblyman Adam Gray, D-Merced, launched a statewide audit on the Department of Water Resources in 2022, after the agency consistently overestimated the amount of runoff from mountains into rivers and streams in 2021, in some cases by as much as 68%

Water supply forecasts from the Department of Water Resources are used in several important ways: Farmers determine crop planting patterns, irrigation schedules, and whether or not to pump groundwater; by cities and counties assessing water supplies and the need for conservation; and for the planning of public services for hydroelectric power generation.

In 2021, the agency forecast more water than was available, causing customers to wait for water that they ultimately did not receive. It was the third driest year on record for California, in the midst of the three driest years on record for California.

“Given the drought and the impacts of climate change, we have to be able to correctly measure every drop and be precise in what water we release and what water we store,” Gray said Friday. “Hopefully, we will learn the lessons from this audit and invest in the tools and methods necessary to measure our water in the future as accurately as possible.”

It is “reasonable” for the state auditor to point to the Department of Water’s shortcomings in incorporating climate change, since “current forecasts in most parts of the world take very little account of climate change,” said Jay Lund, director of UC Davis. Center for Watershed Sciences and expert in water policy and management.

However, Lund said it can be difficult for water managers to account for climate change in their models, since the details of how much and how fast the climate is changing can be unpredictable.

“It’s nice to have some kind of scrutiny, but I don’t think I would have gone as hard on (the Department of Water Resources) for this,” Lund said.

The Department of Water Resources relies heavily on historical climate data when developing its forecasts, while other federal and local agencies use models that directly account for factors relevant to climate change such as temperature and soil moisture, according to the state auditor.

The agency disagreed with the audit findings, writing in response to the report that the Department of Water Resources expanded its use of machine learning, launched airborne snow-watching programs and reduced its data sets from 50 to 30. years, among other improvements.

“Responding to new climate extremes and conditions outside the bounds of historical experience, such as those experienced in the 2020-21 hydrological year, the focus of the audit, requires time, because new tools must be developed to characterize conditions and shape to forecasts significantly. ”, the agency wrote.

The state audit also accused the Department of Water Resources for not having a “comprehensive long-term plan” to mitigate or respond to the effects of the severe drought on the management and supply of water to state customers.

The agency created its first drought contingency plan in 2010, two years after an active drought, and has developed strategies to respond to droughts as they occur, but no other plans to prepare for future droughts, according to the state audit.