Published 10:57 am Thursday, March 23, 2023
MARIN COUNTY, Calif. — The marine fog that rolls across Marin County, Calif., north of San Francisco, relieves drought, even on days when no rain falls.
Moisture collects on the roofs of the barns at Jessica and Neil McIsaac’s dairy and trickles into gutters and two 5,000-gallon tanks.
Pumps then push the water through pipes from the tanks to a pond. In this way, the McIsaac dairy provides water for its 300 milk cows.
“We’re always capturing water, not just on a rainy day,” Jessica McIsaac said. “We’re ecstatic about it. It’s the farmer’s mentality. We’re doers.”
At the moment, California has so much water that Gov. Gavin Newsom has relaxed laws to let Central Valley farmers flood their fields to replenish the aquifers below. A three-year drought had stressed the underground reservoirs that cities and farmers relied on.
But the inland reservoirs filling with Sierra Nevada snowmelt do not irrigate the coastal county where the McIsaacs live. Farmers and ranchers there rely on capturing rain water and condensation from fog running off the hillsides and roofs.
“I’m loving this winter. We’re quite happy with the rain. None of us are complaining,” said Linda Righetti Judah, whose father, Dave Righetti, owns the Lazy R Ranch, a beef cattle operation.
Until this winter, Marin County, like the rest of California, was in a drought. With ponds dry and the state’s $51 billion agricultural economy in trouble, the Marin Agricultural Land Trust started awarding grants in 2021 for drought-relief projects.
The trust supports 73 projects. The projects include redeveloping fresh water springs, installing irrigation lines and adding pumps, many solar powered. Two projects — at the Lazy R and the McIsaac dairy — harvest rainwater running off roofs.
“It’s a newer practice,” said Eric Rubenstahl, the trust’s associate stewardship director. “It’s more on the innovative side.”
In the Midwest, many farms historically relied on cisterns to collect rainwater, and countless western homeowners catch rainwater in barrels for their gardens or household uses.
“I think that’s probably going to be changing. People are looking at more innovative ways to capture and store water,” he said. “I think it’s going to be something on people’s minds.”
The beauty of the collection systems is their simplicity.
“These systems are not that complicated, and they can be really effective if you have the right kind of setup,” Rubenstahl said. “It only kind of pencils out if you have bigger roofs.”
A rule of thumb is that 1 inch of rain falling on a 1,000-square-foot roof yields 600 gallons.
The systems at the Lazy R and McIsaac dairy are examples of scaling the practice to commercial agriculture. Rubenstahl said he hasn’t found many other examples.
In Sonoma County, just north of Marin County, the state in 2015 helped fund a large system at a dairy that allowed it to leave more water in a creek for fish.
California, Oregon, Washington and Idaho all allow rainwater harvesting without a water right. Some water laws apply. For example, rainwater harvesting can’t impair existing water rights.
In Washington, harvesting rainwater also can’t impair in-stream “values,” according to a policy the Department of Ecology issued in 2009. The policy remains in effect.
Buildings can’t be put up in Washington to just harvest rainwater. They must have some other primary purpose, like a barn. There is no limit on how much water can be collected, however.
Ecology spokesman Jimmy Norris said he could find no record or recollection of the department ever asking anyone to stop harvesting rainwater. The Washington State Dairy Federation knew of no dairy that harvests rainwater.
The Lazy R Ranch and McIsaac dairy were motivated to harvest rainwater by the same problem. With ponds dry, they had to haul in water for their cows.
“That’s been a hardship, and all the forecasts say this is the new normal, and we need to become more resilient,” Righetti Judah said.
During the recent drought, the McIsaacs hauled water in for 19 straight months. “We are dependent on rainfall,” Jessica McIsaac said. “We don’t have any wells on our property.”
The agricultural land trust contributed $15,000 toward a $40,000 investment at the dairy. The project included 700 feet of pipe to convey the water to a pond.
“This opportunity came along at a really needed time, so it was a no-brainer,” McIsaac said.
The 220-acre Lazy R received a $5,000 grant. The entire project cost about $6,500, Righetti Judah said. The project also included planting vegetation along a creek through the ranch.
“It didn’t eliminate our need to haul water, but it put a dent in it,” she said. “Hopefully, we’ll be hauling less.”
Rainwater harvesting in towns, where impervious surfaces such as asphalt dominate, has the advantage of reducing polluted stormwater running into city sewers.
Rubenstahl said the trust hasn’t heard concerns that catching water in the country will harm streams.
“I’m kind of surprised there hasn’t been more pushback,” he said. “We’ll definitely be keeping a pulse on that.”
