Sonoma Valley park tour highlights county’s revived vernal pools

Undeterred by a leaky rubber boot, 9-year-old Siena Kelly got a kick out of a visit to a vernal pool Saturday morning at Sonoma Valley Regional Park.

“Really cool,” declared the third-grader at Sonoma’s Flowery Elementary School. “I saw a tadpole.”

Siena was the sole youngster among the 12 people who took a guided tour of the pool, a threatened habitat that harbors endangered species but was in plain view, less than a stone’s throw from busy Highway 12, at the edge of the 202-acre park.

In plain view, that is, if one knew where to look as the morning fog lifted, shedding bright sunlight on green grass refreshed by heavy rain Friday.

The star of the show - a small yellow flower called Sonoma sunshine - opened wide from its overnight rest.

The little flower, an endangered species under state and federal law, is a telltale sign of a vernal pool, said the guide, Hattie Brown, the Sonoma County Regional Park natural resources program coordinator.

Sure enough, the flowers filled a slight depression in the field about 30 feet long, growing in about 3 inches of water on soggy ground.

“This is it,” Brown said. “It’s not often you get to see places like this.”

With standing water all about along the North Coast after a historically rainy winter, new life abounds, including plants and animals that need such habitat to thrive. They were at a loss during the state’s prolonged drought, but copious runoff has come to the rescue, boosting both surface and groundwater supplies.

Still, vernal pools are a rare thing in California.

Experts say 90 percent of the state’s vernal pools have been obliterated by urban development and agriculture. What’s left, Brown said, is “one of the last vestiges of historic California landscape.”

Vernal pools are most prevalent in the Central Valley and occur locally in the Santa Rosa Plain between Sebastopol and Santa Rosa, said Brown, who happens to be author of the “Field Guide to the Vernal Pool Plants of the Santa Rosa Plain.”

The pool in the Sonoma Valley park “is an outlier,” she said.

Asked the difference between a puddle and a vernal pool, Brown said the latter form atop an impermeable underground layer, such as clay, that prevents rainwater from draining downward and therefore last longer than puddles.

But vernal pools eventually dry up in summer or fall, making them a tough environment for the plants, crustaceans, amphibians and insects that inhabit them.

“It’s a pretty harsh place to make a living,” Brown said.

Sonoma sunshine is one of the plant species adapted to vernal pools, and the entire world population of the flower lives in Sonoma County, where vernal pools have sometimes complicated new construction.

Development is the greatest threat to vernal pools, Brown said. Ranking second is the invasion of non-native grasses, which die and lay down a thatch that inhibits the growth of other plants.

Conservationists have mixed feelings about publicizing the location of vernal pools on publicly owned land, she said.

Linda Romero of Santa Rosa, a retired forester who took the tour, said she has been “chasing vernal pools all my life.”

Pools in San Diego County feature flowers of many colors, she said.

The pool in the Sonoma park, she said, is “pretty awesome.”

“I don’t think developers recognize the importance of the ecosystem,” Romero said. “But that’s another story.”

Luda Fiske of Santa Rosa said the tour was his first encounter with a vernal pool.

“A little anticlimactic,” he said, considering the short walk from the parking lot to the pool. “But I’m glad to see it.”

Fiske, who knelt to take close-up photos of the Sonoma sunshine, said he would head out on park trails in search of other flora, such as shooting stars or lupine.

Gianna Kelly said she had read about vernal pools and found it “nice to know what they look like - what defines them.”

Her daughter, Siena, was all for the early morning visit to the park.

“Yeah, I like science,” she said. “My sister didn’t want to come.”

Allegra Kelly, 7, was at home “cleaning up the dollhouse,” she said.

As tour group members departed, Brown informally deputized them as defenders of vernal pools.

“Keep your eye on this pool,” she called out. “You’re all anointed as protectors of this environment.”

You can reach Staff Writer Guy Kovner at 707-521-5457 or guy.kovner@pressdemocrat.com. On Twitter @guykovner.