This winter’s storms piled so much snow on the Sierra Nevada that people standing on Mount Diablo could see the range as a serrated band of bright white on the horizon. That’s good news for the millions of Bay Area people who get their drinking water from snowmelt.
The recent drought is a reminder, however, that we can’t always count on this wealth of water from the mountains. Furthermore, climate change is projected to diminish the snowpack, giving us less water even during wet years; and warmer temperatures will likely make the snow melt earlier, giving us a flood of water in the spring instead of a relatively steady supply that lasts through the summer and fall.
To prepare for the dry years that will come again as well as an uncertain future, healthy mountain watersheds will be key to our water supply. While the importance of forests to these watersheds is well known, new research suggests that meadows are valuable too.
Meadows are like sponges, soaking up snowmelt in the spring and releasing it through the dry season. “There’s no new water but it changes the timing,” said Luke Hunt, an ecologist who is director of headwaters conservation for American Rivers, a national non-profit dedicated to protecting and restoring rivers. And although forest covers more of the watershed, meadows are where the connection between the mountains and the water supply is most obvious. “You can see water bubbling up between your toes,” Hunt said.
The Sierra Nevada has about 280,000 acres of meadows, and roughly half are degraded. Notably, after the Gold Rush, ranchers dug ditches in mountain meadows to drain them for cattle grazing. The ditches eroded over time, often becoming as much as eight feet deep and 50 feet across, and snowmelt now rushes through these degraded meadows instead of being soaked up and stored for later.
Two Bay Area water agencies — the San Francisco Public Utilities Commission (SFPUC) and the East Bay Municipal Utility District (EBMUD) — get most of their water from the Sierra Nevada. However, EBMUD gets water from the Mokelumne watershed while SFPUC gets water from the Tuolumne watershed, and the latter is less at risk of losing snowpack due to climate change.
“We’re lucky that we have extremely high peaks,” explained Tim Ramirez, SFPUC’s natural resources and lands management division manager. The Tuolumne River’s headwaters begin at the base of a glacier on Yosemite National Park’s Mount Lyell, which has an elevation of 13,000 feet. In addition, most of the land that drains into Hetch Hetchy — SFPUC’s reservoir in the park — is above 6,000 feet, and the reservoir itself is at 4,000 feet. All this means that as climate change pushes the snowline up the mountains, the Tuolumne watershed will still be relatively rich in snow.
In contrast, the Mokelumne watershed and the reservoir it fills are at much lower elevations. Most of the land is below 6,000 feet and Pardee Reservoir is down in the foothills of the Sierra Nevada, at just 600 feet.
To help protect its water supply, EBMUD has joined forces with other water agencies to form the Upper Mokelumne River Watershed Authority (UMRWA). Current restoration efforts spearheaded by UMRWA include two projects in the Stanislaus National Forest, which borders Yosemite National Park. Each project is about a thousand acres, and goals include thinning undergrowth to make the land more meadow-like, said David Briggs, EBMUD’s manager of water operations and UMRWA representative. Besides reducing the risk of intense fire and subsequent erosion that can clog reservoirs and make water too full of sediment to treat, restoring the landscape to be more meadow-like could benefit the water supply in several ways.
Snow that falls on the ground lasts longer and yields more liquid water than snow that falls on a forest. “When snow is stuck on trees, it can be blown into water vapor and gone,” Briggs said. In addition, thinning decreases the water that is taken up by plants. And, of course, meadows increase the capacity to absorb and store water for the dry season. “It’s very useful,” Briggs said. “Everybody has a need for water in the summer.”
UMRWA has also proposed restoring several meadows in the Mokelumne watershed. “Increasing water in the meadows would enhance the yield of cold, clean water through the summer,” wrote UMRWA Secretary Lisa Stuart in the minutes from the authority’s January 26, 2018 board meeting. “The improved flow of cold water in the late fall is also a value to salmon and steelhead downstream as well as water agencies. This is becoming increasingly important through the years with the gradually shrinking snowpack.”
The minutes also cited a 2012 restoration project in a meadow called Indian Valley, which sits on the crest of the Sierra Nevada in the Mokelumne watershed, near Lake Tahoe. The project was a great success. Restoration doubled the flow of water from the meadow, according to a 2018 study led by American Rivers’ Hunt and reported in the Journal of the American Water Resources Association.
Moreover, the study confirmed that meadows can soak up water in the spring and store it until summer. During the spring, more water flowed into Indian Valley than flowed out. The opposite was true during the summer: more water flowed out than flowed in. Notably, the study was done during the last drought, when the stream through Indian Valley ran dry for part of the summer. Even so, water flowed out of the meadow all summer long.
That said, the amount of water that meadows can store is modest. Even if all the degraded meadows in the Sierra Nevada were restored, their total storage capacity would be perhaps 70,000 acre-feet of water per year, according to the Sierra Meadows Partnership, an alliance of researchers, non-profits, and state and federal agencies. For comparison, EBMUD customers collectively use about 20,000 acre-feet of water per month. “Meadow restoration is not going to solve California’s water problem — but it is one of the tools,” Hunt said. “Meadows are part of California’s water infrastructure.”
The importance of natural water storage is highlighted in the 2016 California Water Plan, which guides efforts by the state’s Department of Water Resources (DWR) to manage water sustainably. “Meadows act as natural reservoirs, storing and releasing snowmelt and rainfall runoff,” states the plan.
Meadow restoration also helps at-risk wildlife. Besides providing water for salmon, mountain meadows provide habitat for other threatened and endangered species, including amphibians such as Yosemite toads and yellow-legged frogs as well as birds such as Bell’s vireo and willow flycatchers. “Meadow restoration is a multibenefit strategy,” said Lewis Moeller, a DWR project manager for the California Water Plan. “It not only has the potential to retain water from a time of plenty to a time of shortage, but also has ecological benefits.”
The biggest obstacle to meadow restoration is funding, but the state has begun to move forward on that. Proposition 1, the $7.12 billion water bond that California voters passed in 2014, provided nearly $1.5 billion for “multibenefit ecosystem and watershed protection and restoration projects.” In addition, Proposition 68 — the $4 billion bond supporting parks, water, and the environment that passed in 2018 — provided $85 million for restoring mountain watersheds. Of that, $25 million was dedicated to forest and meadow systems, and $60 million was for projects with a range of benefits, including restoring meadows and protecting the water supply.
The contribution of meadows to the water supply may be small but, especially in a dry year, every drop is welcome. “Some of EBMUD’s water now comes from Indian Valley,” said Hunt. “When you take a sip, you can know that some of it is there because of restoration.”
Robin Meadows covers water for the Monitor.