Cosumnes River Preserve

Posted: Jun 1, 2005
Written by: 
Brendan Smith

The Cosumnes River flows 80 miles from the western slope of the Sierra Nevada through California's Central Valley to its confluence with the Mokelumne River and the marshes of the Sacramento-San Joaquin Delta approximately 20 miles south of Sacramento.

Objective: The Cosumnes River Preserve is dedicated to:
  • Safeguarding and restoring the finest remaining example of a California valley oak riparian ecosystem and its surrounding habitats;
  • Restoring and creating freshwater wetlands to increase the Pacific Flyway's populations of migratory waterfowl; and
  • Demonstrating the compatibility of human uses, particularly agriculture, recreation, and education, with the natural environment.
Participants: The Nature Conservancy of California, U.S. Bureau of Land Management, Ducks Unlimited, California Department of Fish and Game, California Department of Water Resources, Wildlife Conservation Board, State Lands Commission and Sacramento County

 Vernal pools are seasonal wetlands that form in depressions where the underlying soils trap water.
Photo courtesy of US Fish & Wildlife Service
History: Described as "the garden of California" by 19th-century explorer James C. Carson, the Central Valley once encompassed tens of thousands of acres of wetlands and riparian forests. Today, after more than 150 years of intensive farming and ranching, only 5 percent of the wetlands remain. Yet, by luck or happenstance, the Cosumnes remains the last free-flowing river on the western slope of the Sierra Nevada. From its headwaters in the El Dorado National Forest, the river descends into the Central Valley, supporting seasonal wetlands called vernal pools, and nourishing rare valley oak groves. Although levees restrict some water flow, the Cosumnes often floods its banks during winter storms, sustaining a natural floodplain that has all but disappeared elsewhere in the Central Valley. With no dams blocking their path, Chinook salmon and Pacific lamprey still make their seasonal runs upstream to spawn. Up to 60 percent of the Pacific Flyway bird species and 20 percent of continental waterfowl populations winter in or migrate through the Central Valley, according to Ducks Unlimited, a nonprofit group dedicated to conserving and restoring wetlands for North American waterfowl. The Cosumnes provides critical feeding and nesting habitat.

Sandwiched between the growing cities of Sacramento and Stockton, much farmland in the Central Valley has been lost to development or converted to more profitable vineyards. Two decades ago, The Nature Conservancy (TNC) noticed the changing character of the landscape and the potential threats to the Cosumnes River. "We recognized the larger region of the Lower Cosumnes had a lot of values," says Mike Eaton, TNC's senior project director for the Delta/San Joaquin Valley. "The Cosumnes River Preserve rapidly got on the map of conservation in the valley."

In 1984, TNC purchased its first parcel along the Cosumnes, 85 acres of virgin valley oak groves. Ducks Unlimited followed suit, purchasing an additional 320 acres. In 1987, following a second TNC land purchase, the two organizations established the 1,000-acre Cosumnes River Preserve. Today, the preserve has grown to almost 50,000 acres, with additional partners conserving land through acquisitions or conservation easements. The BLM joined the preserve in 1989 and now manages its visitor center.

Accomplishments: Approximately 90 percent of preserve lands are farmed or grazed, including 15 parcels covered by conservation easements that restrict certain land uses but do not interfere with profitable farming or ranching operations. In the late 1990s, rancher Jim Chance sold an 8,000-acre conservation easement on his Merced Ranch to TNC in order to permanently protect vernal pools and endangered fairy shrimp habitat. In turn, Chance bought the 12,362-acre Howard Ranch from TNC in 2001. Named for former owner Charles Howard who also owned the famed racehorse Seabiscuit, the Howard Ranch includes prime wildlife habitat, blue oak woodlands, and cattle pastures. An easement prohibits development or the planting of vineyards and orchards, protects vernal pools, and restricts the number of cattle and the length of the grazing season. "I have had no problems. They haven't gotten in my way at all, and I've made some good friends," Chance says of working with TNC. "It's a way to keep grazing land intact without development, which is just running rampant through the Central Valley at the moment. I really wanted to keep [the land] the way it was."

 Sandhill cranes spend September-March at the preserve. Numbers of the birds have dramatically increased since land managers began planting bird-friendly crops.
Photo by Will Cook
TNC also is learning from local farmers. In 2001, TNC purchased the 9,200-acre M&T Staten Ranch on Staten Island in the Sacramento-San Joaquin Delta to protect critical habitat for thousands of sandhill cranes and other Pacific Flyway birds that winter over and feed in flooded fields. TNC hired Jim and Sally Shanks, who had managed the farm for more than 50 years, and eight other farm employees to work for a new nonprofit affiliate called Conservation Farms and Ranches that now manages Staten Island. The Shankses had been practicing bird-friendly management techniques for decades. "It's been a nice marriage of Staten Island and the cranes, and we accommodate them. The birds come to these same fields at the same time and spend the whole winter with us," says Sally Shanks. "In the course of managing, we have skewed the decisions for the birds or kept the birds in mind when we make decisions." Corn and wheat are grown on Staten Island, low-profit but bird-friendly crops that succeed through economies of scale, Sally Shanks says. After the harvest, corn stubble and crop residue are ground and left as feed for the birds. Since the island is located below sea level, fields are flooded during the winter to provide wetland habitat for birds.

Mike and Laura Johnson also live and work in the Cosumnes River Preserve. In 1998, they bought 625 acres along the Cosumnes River from TNC. The property, which is adjacent to their family farm, is covered by a conservation easement prohibiting development or planting of orchards and vineyards. They raise corn, tomatoes, seed crops, and more than 300 head of cattle. "They have been pretty much a silent partner," Mike Johnson says about the preserve. "At the time, I couldn't buy the land without them. It made sense to me." The Johnsons also lease 400 acres from the preserve to grow rice.

Approximately 30,000 people and more than 5,000 students visit the Cosumnes River Preserve each year. The visitor center offers a mix of educational and recreational opportunities, including hiking, bird watching, canoeing, and kayaking. The center's staff illustrates the collaborative character of the preserve. It includes preserve manager Rick Cooper and two other BLM employees; a recreation specialist employed by the Sacramento County Department of Regional Parks, Open Space and Recreation; and a teacher from the Galt Unified School District who oversees field trips and a student volunteer program. Mike Eaton and five other fulltime TNC employees also work on the preserve or its related conservation efforts. "The partnership aspect is real," Eaton says. "I get asked all the time if this is just window dressing. No, we all pull together."

The preserve also partners with University of California-Davis and the Point Reyes Bird Observatory to carry out scientific research. UC-Davis is studying the use of levee breaches to restore floodplain habitat. The Point Reyes Bird Observatory monitors bird populations, nesting areas, and impacts of rat predation on songbird nests.

Challenges/constraints: The Cosumnes River Preserve faces encroaching urban development. "There's a lot of land speculation which is getting very close to us," Cooper says. "Our objective is to keep that urban development a little farther away and to create a buffer zone so we can actually allow this river during floods to spread out and meander." Agricultural land that sold for approximately $3,000 per acre a decade ago now fetches from $10,000 to $18,000 per acre. "There isn't a whole lot of funding for us or our partners to tap for more land acquisition," Eaton says. Increased groundwater pumping also has lowered river flows, sometimes delaying the autumnal upstream runs of Chinook salmon.

To reduce development impacts, TNC works with local governments to promote urban infill development and on a mitigation program to compensate for the loss of open land. In 2004, the city of Elk Grove began requiring developers to protect one acre of undeveloped land for each acre of open land developed within city limits. TNC hopes that development mitigation credits, either outright land purchases or conservation easements, will add to the preserve. This year, Sacramento County began a similar mitigation program.

The Central Valley's growing prominence as wine country poses threats to wildlife and riparian habitat. Vineyard owners often use a "deep ripping" process, which tills the soil more than three feet deep to allow grapevines to take root through a hardpan layer of clay beneath the topsoil. The process destroys the soil structure and causes vernal pools to dry up.

Despite the varied pressures, Jim Chance and others working with the Cosumnes River Preserve are optimistic about their efforts to save a piece of old California. "I think it looks good," Chance says. "There are more and more people who would rather preserve the ranchland rather than [see it] going into development."

For more information see:

Cosumnes River Preserve

UC Davis Cosumnes Research Group

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