Jepson Prairie Preserve

The Jepson Prairie Preserve is an ecologically sensitive habitat open to the public for simple walking tours. The best way to see it, however, is with a docent who can point out the special species seen here and is authorized to dip into the pools to look for water creatures.

• Easy to Locate? Yes
• Pet Friendly? No. This is a sensitive habitat area. No pets allowed
• Easy to Walk? Yes
• Is there a Fee? No.
• Are there Restrooms? Usually, there’s a porta-potty by the main gate.
• Is there Accessible Parking? Yes
• Other Notes: The best time to go is in the spring when there is water on the landscape. In the summer months, the grounds are very dry and there is less for the casual viewer to see.

See my FLICKR account for more albums of photos taken at this location.

Overall, the place is about 2.5 square miles and comprised of relatively flat prairie land, mima mounds, and a variety of vernal pools. It’s one of the few surviving vernal pool habitats and native bunchgrass prairies in the state.

The whole thing is surrounded by agricultural land. The largest, deepest pool is called Olcott Pool, a large “playa pool” that can be seen, when it’s full, on both sides of the road. In 2021, there was so little rain that the water covered an area about the size of a bath tub. In 2022, it was much more impressive.

“…Two years after the Nature Conservancy purchased the 1,566-acre site, it was dedicated as the Willis Linn Jepson Prairie Preserve in 1982. In 1983, the University of California brought the preserve into the University’s Natural Reserve System. In 1987 the National Park Service designated Dixon Vernal Pools, of which Jepson is the centerpiece, a National Natural Landmark…” So, it’s a very special place.

Here is part of the writeup on the place from the preserve’s website and brochure: “…Vernal pools are temporary bodies of fresh water created by winter rains. A clay layer just under the surface soil expands and creates an impermeable barrier, so rainwater fills the low spots as the soil is saturated. These pools become the habitat for a complex world of plants and animals which adapted over time to survive a habitat that floods in winter and then dries completely during the hot summer months…

“…The reserve protects several seasonal playa lakes and one of the best remaining networks of clay-pan vernal-pool habitat in the Central Valley… Altogether over 400 species and 64 families of plants, including 15 rare and endangered plants, are found on site…

“Many of the showiest vernal pool flowers (Yellow Carpet, Meadowfoam, Goldfields, and Downingia) are pollinated by native specialist bees in  the family Andrenidae. These solitary, ground-nesting bees use the pollen of specific flowers to feed their young. And, during the course of collecting pollen to provision their nests, they perform the vital function of cross-pollinating the vernal pool flowers…Each of the four plant groups listed above has one or more native specialist bees that collects pollen only from them. The life cycle of these bees is closely synchronized with that of their pollen host flowers. While generalist and non-native bees, such as the honey bee, and other insects also visit most of these flowers and may potentially pollinate them, research shows that at least some of these flowers may require their specialist pollinators for successful reproduction and seed set…”

You can read more in an article from Bay Nature magazine HERE.

There are some specialized and endemic plant species there, most of them adapted to growing in the vernal pool environment, some of them quite short and stunted, or very, very small: Maroonspot Calicoflower [a kind of downingia], Dwarf Brodiaea, and Sea Mullia. 

It’s a very specialized, unique and somewhat tenuous habitat that needs to be protected or we’ll lose all of the rare, endemic, and endangered species currently found there.

How to Get There:

From Sacramento:

  • Take Highway 50 West
  • Highway 50 West will merge with I-80 Business West
  • I-80 Business West will merge with I-80 West
  • Stay on I-80 West past Davis, Ca
  • Take Exit 66A to Highway 113 to Dixon
  • Stay on Highway 113 through the town of Dixon
  • You’ll come to a spot where the highway takes a sharp left turn just before the preserve. At this point KEEP GOING STRAIGHT and STAY ON THE GRAVEL ROAD.
  • The preserve will be on your left and right of this road, and the turnout is well-marked. Park where you are not blocking the road or the gate (which will be on your right).

See the website HERE for more details, including maps, brochures and a link to their events page.

Travels of a Certified California Naturalist

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