Only 8% of California’s rivers and streams have gauges that track flow

In the face of climate change and worsening drought cycles, California water managers are increasingly focused on accurate tracking of water resources. Snowpack in the Sierra Nevada is measured with sensors and aerial images, reservoir levels are electronically logged, and water movement through aqueducts is apportioned based on rights and contracts.

However, there is another important water parameter that California has never adequately measured: the flow of rivers and streams.

New research by UC Berkeley scientists found that only 8% of the state’s rivers and streams are equipped with gauges — devices that measure the level and speed of water.

StudyThe study, published in the journal Nature Sustainability, details large stretches of the state’s waterways that are not monitored and examines the impacts on humans and wildlife as climate change accelerates the water cycle, alters watersheds and threatens vulnerable fish and other species. The researchers also outline ways for California to select new monitoring locations to expand its network of stream gauges.

“We can’t manage what we can’t measure,” said lead author Lucy Andrews, a researcher in UC Berkeley’s Department of Environmental Science, Policy and Management.

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Of earlier Research It showed that not only are many of California’s rivers overallocated, but existing water rights are also Above average supply Many rivers have flooded. Inadequate data collection exacerbates these chronic problems, the study authors said.

“If we don’t know how much water is flowing through our rivers and streams, it becomes very difficult to make decisions about how to allocate it,” said study co-author Ted Grantham. “We need to know how much water is available, and we also need to know how much water is being used. And California is really underfunded in both of those areas.”

Poor monitoring not only hampers the state’s ability to monitor supplies and manage flooding, Grantham said, but it also clouds our understanding of how water diversions and droughts caused by climate change are threatening fish and other aquatic species.

A stream gauge near Pine Flat Dam on the Kings River measures flow downstream of the dam.

(Ted Grantham/UC Berkeley)

“The only way we know if there’s enough water left in the river to benefit the environment is to measure it,” said Grantham, a river scientist and Cooperative Extension associate professor. “And if we’re failing, if we don’t have the ability to know how much water is in the river, it takes just a little bit for the river to dry up, which has extremely negative impacts on the species we care about.”

California is recognized as a global hotspot of biodiversity, with freshwater species among the most threatened in the world. The list of fish species at risk of extinction includes winter-run Chinook salmon, steelhead, green sturgeon, and delta smelt.

“More monitoring of these important streams is needed to protect these endangered species,” Andrews said. “If we maintain the status quo, and if we don’t know how much water is in rivers and streams, we are essentially dooming some of our freshwater species.”

In another recent incident ReportResearchers at the Public Policy Institute of California assessed the grave threats to freshwater biodiversity in the state. Studies have shown that nearly half of California’s native aquatic species are highly vulnerable to extinction this century, and researchers said that with climate change accelerating, the state needs to quickly adopt new types of conservation plans and approaches to save species.

“There are no safeguards in place for most of the species we may lose,” the researchers wrote. They added that to reverse freshwater ecosystem declines, usual management approaches likely won’t succeed and “bold, perhaps risky innovations in policy and management are needed.”

While the institute’s proposal for “climate-smart” conservation plans outlines strategies to reverse species declines, the UC Berkeley researchers focus on the critical role of stream-flow monitoring data for informing decisions about water management and ecosystem protection.

Among other findings, Grantham and Andrews determined that only 9% of the state’s 817 large dams have an active gauge, either upstream or downstream, and that only about 29% of catchments with the greatest diversity of aquatic species are monitored.

They found that stream gauges are particularly low in watersheds with minimal human interference. In areas that are mostly untouched by nearby development or diversions, less than 1% of streams are covered by active gauges.

Andrews said this highlights the particular need to expand flow measurements along these streams, where “we can start to see the effects of climate change on hydrology.”

Their analysis also found regional differences, with more gauges installed on streams heavily used for agriculture in the Central Valley and significantly fewer monitoring in other regions, such as streams in the Sierra Nevada, Southern California, the North Coast, the northern Lahontan region and parts of the Scott and Shasta rivers in the Klamath River Basin.

These differences are a significant problem in collecting data at the regional level, the authors said.

“If we leave out certain areas, we can’t talk about the overall effects of climate change on California’s waterways and the water resources available for the economy, cities and farms,” ​​Andrews said. “What’s happening on the North Coast is not going to be the same as what’s happening in the Imperial Valley, what’s not going to be the same as what’s happening in Monterey. And so if we don’t have gauges in all of these places, we’re really flying in the dark.”

The researchers examined 814 active gauges and modeled scenarios in which more gauges are installed across the state. They said adding 500 gauges to the network could more than double the length of streams monitored.

He acknowledged that this expansion would be expensive because each gauge could cost up to $40,000 to install and then additional money would be needed for maintenance. He said that expanding the network would require substantial investments by state, federal and local agencies as well as water districts.

“With proper investment, it is possible to design and build better networks,” said Grantham. “Knowing more about how much water is in our rivers and streams will help us better manage our rivers and streams.”

Andrews said several state and federal officials are working to address the gaps but lack the resources. He said he hopes the study will help the Legislature’s efforts to prioritize funding.

A Previous Analysis A study led by the Nature Conservancy found that 89% of “critical streams” in California are not properly monitored.

Other water experts agree that California should collect more data on rivers and streams, as well as groundwater.

“Without accurate information about the quantity and quality of water in our rivers and streams and in our groundwater basins, it is extremely difficult to develop effective policies to manage our water more successfully and sustainably,” said Peter Gleick, senior fellow and co-founder of the Pacific Institute.

“A major expansion of gauges will allow us to more accurately monitor and enforce water-rights allocations, determine ecological conditions and requirements for threatened and endangered fisheries, and improve California’s resilience to both floods and droughts,” Gleick said. Recent advances in technology, he added, may also allow the deployment of more real-time “smart” gauges that measure not only stream flow but also water quality, temperature and other measures of the health of waterways.

Scientists have found Equal intervals in flow monitoring in areas around the world. Studies have also shown that Long-term decline Lack of funding has caused a steep decline in the number of operating stream gauges in the United States.

Inadequate flow data has long been recognized as a problem in California, and in 2019 the state legislature passed SB 19, a law that directed state agencies Develop a Plan To fill the gaps and install more gauges.

In 2022, state water agencies release their reports Plan To give priority to installation of more gauges.

“A robust and reliable stream gauge network can help state, federal and local agencies more effectively manage water resources for multiple benefits and avoid conflicts,” said Teresa Connor, northern region manager for the state Department of Water Resources.

Connor said in an email that the state currently has about 1,000 stream gauges operating and reporting data. Many of those are maintained by the U.S. Geological Survey, while the Department of Water Resources operates about 300 gauges.

Connor said the state agency has begun upgrading or reactivating about 50 gauges since the plan was completed, and is working with the USGS to bring an additional 11 gauges online with available funding.

“The USGS works closely with many partner agencies in California to identify high-quality streamflow monitoring needs for nearly 500 streamflow stations,” said USGS spokesman Paul Laustsen. “This collaboration means we work together to avoid duplication, ensure critical sites are prioritized for monitoring and provide reliable, unbiased and baseline data to address the water issues facing California.”

In addition to federal funds allocated for stream monitoring, the USGS has received a four-year state contract worth nearly $1.2 million to help address deficiencies in California’s gauge network.