SLT in the News

Jepson Prairie: A mysterious wonder emerges a few weeks a year

Author: Barry Eberling - Fairfield Daily Republic
Date: Dec 28, 2010

Editor's note: Lists of seven worldwide wonders date back to antiquity. Sticking closer to home, the Daily Republic over the course of a week will present seven natural and engineering wonders of Solano County. Agree or disagree with our choices, these are local landmarks everyone should see.

DIXON — Willis Linn Jepson Prairie preserve is a Solano County stealth wonder during much of the year, only to burst into life briefly with stunning beauty.

People visiting there in the summer might wonder why they made the trip. The prairie is dry, brushy and dusty and the weather is often either hot or notable for strong winds rushing across the flat, remote eastern Solano County landscape.

But in the spring, after the rains, Jepson Prairie comes alive. Clay-lined vernal pools fill with water and give life to tiny, rare shrimp. Wildflowers such as brass buttons and harlequin flowers cover the land in purples, whites, pinks and golds.

Fair Oaks resident Bonnie Ross returns each spring. She's been trained as a docent for the preserve and for nine years has given tours to the public.

“The reason I keep coming back is because every year it's different and because it's miraculous,” Ross said.

Among the first people to realize the worth of the county's vernal pool complexes was Willis Linn Jepson. Jepson was born in Vacaville in 1867 and became a giant in botany, writing such influential books as “A Manual of the Flowering Plants of California.”

“On the plains, originally, and to some extent yet, are found little vernal pools which have no outlets,” Jepson wrote in 1912. “These dry up eventually, and their contracting margins support in succession a number of peculiar plants; the delicate blue-and-white downingias, the red dwarf monkey-flower and several others with inconspicuous flowers.

“Finally in midsummer the beds of these pools are filled by the harsh growth of the native coyote thistle.”

Many vernal pool complexes have given way to development in the Central Valley since Jepson penned those words, putting many of the creatures and plants that thrive in this habitat at risk of extinction. Jepson's prose during his lifetime proved too little to get any of the vernal pool complexes in Solano County preserved.

That didn't happen until the Nature Conservancy in 1980 bought 1,566 acres with vernal pools near Highway 113. The land was named the Willis Linn Jepson Prairie Preserve in 1982 and was transferred to the Solano Land Trust in 1997. The preserve is part of the University of California Natural Reserve System and is used for research.

Ross talked about such Jepson Prairie features as Olcott Lake. This vernal pool is the largest on the prairie at 93 acres when full, about twice the size as Fairfield's Allan Witt Park.

Inside Olcott and other vernal pools swim such rare creatures as the vernal pool fairy shrimp, the tadpole fairy shrimp and the conservancy fairy shrimp. These delicate, translucent creatures are less than an inch long. They live only a few months.


But in one respect fairy shrimp are amazingly hardy—their egg-like cysts can survive in the soil for decades before hatching. In fact, the cysts can survive near-boiling water, freezing temperatures and a decade in near-vacuum conditions, according to the California Academy of Sciences.

Ross also talked about a type of bee at Jepson Prairie, called a solitary bee because it pollinates only one type of flower.

According to the California Academy of Sciences, these bees' entire lives are centered on goldfield flowers. The females make a ball with goldfield pollen, put it in an underground tunnel and lay a single egg on it.

“You would never see those flowers without those bees,” Ross said.

Jepson Prairie holds the distinction of being home to the Delta green ground beetle, which is found in this area and nowhere else in the world. Its color, of course, is a metallic green.

Vernal pools also provide flood control, recharge the water table and provide water for migrating waterfowl, Ross said.

“They're just not sitting there for nothing,” Ross said. “They are providing ecological functions that help everybody, even the people who don't come.”

Jepson Prairie is one of the few places where the public can see vernal pool habitat, Ross said. People can take guided tours beginning in early spring and also take self-guided tours. Go to for more information.

Willis Jepson should get the last word on the Solano County wonder that bears his name. He wrote scholarly tomes, true, but he also co-founded the Sierra Club and could put some passion in his writings.

In his 1912 article on Solano County flora and fauna, he made a case why people should care about such places as the vernal pool complexes.

“For there be many who love this land of hills and plains and the native life which is here nourished, and to these life is made sweeter, the sympathies enlarged and the home loyalties deepened,” Jepson wrote.

Reach Barry Eberling at 425-4646, ext. 232, or