A MATTER OF INCHES FOR SALMON IN PERIL ON THE COSUMNES

By Robert Glennon

NOTE: Robert Glennon is a professor of law and public policy at the University of Arizona's James E. Rogers College of Law. This article is excerpted from his new book, "Water Follies: Groundwater Pumping and the Fate of America's Fresh Waters." SCCRG has been granted copyright permission by the publisher, Island Press.

The most majestic of Pacific Ocean salmon, Chinook or king salmon typically weigh between 10 and 50 pounds. Chinook may travel 2,000 miles during their ocean migration, yet miraculously find their way back to spawn in the river where they were born.

A beautiful fish prized by anglers as well as chefs, Chinook are silver, slender and muscular. As they navigate upriver, they may jump waterfalls as high as 10 feet. In the spawning process, their silvery bodies gradually turn a deep red.

In the Cosumnes (kuh-SOOM-ness) River, which flows just south of Sacramento, Chinook face such enormous obstacles to survival when they hatch that it's a wonder any survive to spawn. Droughts can dry up spawning beds, and floods may wipe out beds or deposit silt that deprives the eggs of needed oxygen. Only a small percentage of eggs become young salmon fry – each about an inch long – and 90 percent die as they move downstream to the ocean.

On the downriver voyage, young Chinook undergo a transformation in their bodies that enables them to survive in salt water. If low flows delay the journey, the smolt process may reverse itself. Along the way, the young salmon encounter osprey and other fish-eating birds, as well as largemouth and striped bass, voracious predators of baby salmon. They may also lose their way by going into irrigation canals – mazes from which they may never return.

Once in the ocean, they migrate as far north as Alaska but may encounter commercial fishing nets along the way. Chinook find their way home to the Cosumnes from the Pacific by swimming under San Francisco's Golden Gate Bridge, heading north in San Francisco Bay, then past San Pablo Bay and Suisun Bay, where they risk predation by sea lions and other marine mammals.

At the Delta, where the Sacramento and San Joaquin rivers converge, Chinook need to pick up a Cosumnes River odor trail if they are to head south up the San Joaquin, into the Mokelumne River and, finally, into the Cosumnes. Chinook enter the river in September and October and then face the cruelest fate of all, one from which there is no escape. As they swim upriver, they arrive at the section that is bone-dry. They must wait for the fall rains and hope that the river begins to flow.

Historically, two or three million Chinook annually returned to spawn in California's Central Valley rivers. Commercial Chinook fishing in California started in about 1850; most salmon were destined for canneries, some for export to Australia. Today, only 200,000 return, and some of them are hatchery hybrids. Spawning by wild Chinook is minimal; many species of Chinook have become extinct. The decline of Central Valley Chinook is the result of overfishing, mining activities that degraded the streams, and dams and water diversions that reduced salmon habitat.

The Cosumnes River, Northern California's last major river without a dam, flows out of the lower Sierra Nevada foothills west into the great Central Valley, below Sacramento. The Cosumnes is a small, unassuming river compared to the American River to the north and the Mokelumne River to the south; it carries a modest volume of 365,100 acre-feet of water per year (af/yr), or 505 cubic feet per second (cfs), about one-seventh of the flow of the American and one-half of the flow of the Mokelumne. In September and October, at the end of California's dry season, the Cosumnes' flow drops to 27 or 30 cfs.

Ironically. The Cosumnes' low flow is its salvation; otherwise it would surely have been dammed. The Cosumnes once supported a large fall run of Chinook, but dwindling numbers resulted in the U.S. Fish and Wildlife Service's listing Cosumnes Chinook as an endangered species. In recent years, fewer than 1,000 chinook have returned annually to spawn in the river.

The Cosumnes River may have escaped being dammed, but it has felt the weight of the flood control program of the Army Corps of Engineers. In the 1930s, the Corps financed an extensive network of levees that confined the river to its main channel so that farmers could grow crops in the floodplain.

Over time, levees wreak havoc with a river. A floodplain's riparian vegetation, once deprived of water and nutrients, gradually dies. The levees allow the river to transport more water and, with it, more sediment, which comes from the channel bed. This erosion of the channel bed deepens the river, further isolating it from the floodplain.

In the 1950s, the Corps embarked on a "river improvement project" for the Cosumnes. Back then, the Corps preferred straight rivers with deep, narrow channels, so by bulldozing the Cosumnes, cleared the channel and ripped out the trees and vegetation. The Corps used a template that conceived rivers as arteries of commerce. Never mind that freighters had no need for access to the Cosumnes. The "improvement project" produced ungodly amounts of sediment, which moved downstream and scoured out the river's channel, causing what hydrologists call incisement (or entrenchment), and what the rest of us call "steep banks." An incised river channel, by making it more difficult for water to flow over the banks, reduces the amount of water stored in a river's floodplain.

Corps-financed levees and its "improvement project," combined with farmers' groundwater pumping and surface water diversions, have left the Cosumnes in a precarious state. Until the 1940s, the Cosumnes flowed year-round because it received baseflow (discharge) from the extensive floodplain aquifer. But the network of levees has constricted the river's flow and sharply reduced the amount of water that the floodplain can recharge to the aquifer and, in turn, that the floodplain aquifer can slowly discharge to the Cosumnes.

Increased groundwater pumping, especially since the 1950s, has lowered the groundwater table to 55 feet below the river channel and converted the river from a gaining to a losing stream. The river now recharges the aquifer. A five-to ten-mile section of the river (between Meiss Road and Highway 99) actually dries up in the fall at the end of California's dry season.

Until quite recently, little was known about the Cosumnes River and its Chinook; that has changed thanks to the CALFED Bay-Delta Program. Created in 1995, CALFED is a cooperative partnership among federal and state agencies (which accounts for the name), urban and agricultural interests, and environmental organizations that seeks to restore the ecological health of the largest estuary on the west coast of North American – the San Francisco Bay/Sacramento-San Joaquin Delta. Along with the Packard Foundation, CALFED funded Jeff Mount, a geologist at the University of California at Davis, and his colleagues to establish an interdisciplinary research program to monitor the Cosumnes River watershed.

The UC Davis scientists have found that groundwater pumping is "at least partly responsible" for the decline in fall flows and the reduction in the number of fall-run Chinook. As flow in the Cosumnes declined, some farmers stopped using diversion canals and sunk groundwater wells next to the river. Local anecdotes suggest that some farmers even drilled wells at a slant, thereby putting the bottom of the well closer to the river to suck greater amounts of water from beneath it.

Groundwater pumping has lengthened the interval during which the Cosumnes is dry. In the past, the onset of the fall rainy season in November would immediately produce flows in the dry section of the river. Because of the lowered water table, the initial fall rains percolate into the ground. So now, fall rainstorms must completely saturate the dry streambed before the river will flow. As a consequence, the river stays dry well into November. By then, Chinook have already entered the river and are waiting downstream for the intermittent section to fill so that they can dash upstream to spawn.

The flow pattern in the Cosumnes is no longer in sync with the genetics of the fish. If it takes too long for the river to open up, the Chinook will die before reaching the spawning beds. Their fate is a cruel one. Having endured long odds and numerous obstacles during their ocean voyage, they arrive in their natal river only to find it dry. An equally pathetic end came to some Chinook during fall 2001. A November rainstorm opened up the Cosumnes and a couple hundred Chinook raced upstream, only to have the river abruptly stop flowing. The stranded salmon died. Saving the Chinook from extinction, according to Jeff Mount, involves "a game of inches," as the salmon need only seven inches of water to get upriver.

Scientists, environmental organizations and government agencies have enormous interest in saving the Cosumnes because it is the last undammed river, it has endangered Chinook, and it supports the largest surviving valley oak forest. The search for solutions has led to innovative partnerships and unorthodox tactics. In the 1980s, The Nature Conservancy (TNC) embarked on a major effort to preserve and expand the remnants of valley oak forests, the craggy trees once found throughout the Central Valley.

Valley oaks, or swamp oaks, as they are also known, thrive in the Cosumnes River basin because it has a natural cycle of seasonal flooding, at least in those sections without levees. Periodic flooding deposits nutrient-rich silt on the floodplain, which encourages oaks to reproduce and discourages nonnative species from developing. In 1987, TNC purchased an 800-acre parcel, now called the Cosumnes River Preserve.

TNC's traditional long-term strategy for protecting the environment involved identifying a parcel of land that contained rare habitat, fauna or flora and then raising funds to purchase the parcel and preserve it from development. However, TNC has come to realize, reluctantly, that this strategy does not necessarily protect the parcel from the effects of nearby development. TNC ecologists have recently formulated a much broader strategy for conservation at some 75 sites, known as the "Last Great Places," including the Cosumnes River valley.

In 1993, TNC initiated a program to protect the entire Cosumnes watershed, a 1,200 square mile area, by developing partnerships with nonprofit organizations and state and federal agencies. Nurturing those partnerships has required some flexibility. Its first partner, Ducks Unlimited, desired to protect a robust population of waterfowl that rely on the Cosumnes in their migration along the Pacific Flyway. TNC, on the other hand, cared more about maintaining and restoring the valley oak forest. But both organizations came to understand that the two objectives shared a common element: Seasonal flooding created both oak seedlings and the wetlands that ducks love.

As a vehicle for protecting more land – some 40,000 acres – TNC entered into conservation easements with neighboring farmers that impose specific limitations on how the farmers may use or develop their lands. These conservation easements – restrictions placed on deeds – prohibit large-scale residential development and the planting of perennial crops that require intensive agriculture, such as orchards and vineyards. The easements allow agricultural uses that are more compatible with wildlife use, such as the cultivation of rice or corn. Major funding ($18 million) for TNC's land acquisition and conservation easement program has come from CALFED.

Although it may take decades, levees eventually succumb to the power of nature. On the Cosumnes, this happened in 1985 when floodwaters breached a levee and created a sandbar across neighboring farmland. Soon, willow and cottonwood seedlings began to sprout from the sandbar. Then the seedlings attracted scrub jays, which deposited acorns in the soil. Within five years, valley oaks began to flourish.

The lesson was clear: Left to itself, the Cosumnes would begin to recover. Scientists from TNC wondered if they could hasten the recovery. In winter 1995-96, TNC bulldozed 50 feet of levee. The winter rains flowed through the breach onto the floodplain and, as predicted, a new forest began. What was unpredicted was that juvenile Chinook would swim from the main channel onto the flooded fields.

Fishery biologists think that this seemingly odd behavior is actually a genetically developed method of survival. Chinook use the nutrient-rich floodplain (Peter Moyle of UC Davis calls it "a soup of invertebrates") to fatten up before they travel in the spring downstream to the ocean, a fact previously unknown to science and therefore overlooked in other salmon restoration efforts.

Funding for TNC's breaching of the levee came from the Corps, whose engineers were directly involved in planning and oversight, and TNC is exploring with preserve partners and neighboring farmers the possibility of breaching other levees. Environmental restoration often involves nothing more elaborate than tearing down things we have built in the past. It's an exciting development for Jeff Mount, who notes: "We are finally going to get a chance to evaluate the ecological and economic benefits of promoting floods on the floodplain."

Despite the efforts of TNC, its preserve partners and the UC Davis scientists, the Cosumnes faces an uncertain future because of groundwater pumping that supports continuing suburban sprawl. In the last 20 years, a large portion of the Central Valley has begun to support a new crop – subdivisions. The valley's population, currently about 5 million, is expected to double by 2020, partly from folks fleeing the San Francisco Bay region in search of affordable housing. The Cosumnes lies between Elk Grove and Galt, cities that are experiencing rapid growth as bedroom communities 20 to 25 miles south of Sacramento, off Interstate 5. Municipal pumping has created two major cones of depression that already capture water from the Cosumnes.

In addition, the Cosumnes faces threats from three proposed developments: a huge regional shopping mall, a planned community and a destination resort. In June 2001, the Elk Grove City Council gave its approval to Lent Ranch Marketplace, a 295-acre, $500 million, 1.3 million square foot mall, to be surrounded by 1.8 million square feet of commercial space and 280 multifamily homes. The mall would border undeveloped farmland on the southern tip of Elk Grove. Wells to supply groundwater for the development would unquestionably reduce flow in the Cosumnes. The mall's parking lots would practically abut the Cosumnes River floodplain.

A second threat comes from a proposed 29,000-home, 6,000-acre Sunrise-Douglas development, part of a new city – Rancho Cordova – northeast of Elk Grove. Developers would like to pump water from beneath the project, but the California Department of Health Services (DHS), which has jurisdiction over polluted groundwater, has refused to allow pumping. The reckless disposal of defense industry waste from the Aerojet Rocket Testing Facility and Mather Air Force Base in the 1950s poisoned the groundwater with perchlorate and other nasty stuff.

DHS has concluded that the proposed wells are too close to the current edge of the plume of pollution; pumping would draw that plume more quickly toward the wells. The contamination plume might migrate into the taps of tens of thousands of new residents. Sacramento County was relying on these wells to serve the next tier of growth.

DHS's decision has forced Sacramento County and the developers to consider developing a well field father south, nearer the Cosumnes River. Sacramento County officials have concluded that this well field could supply the Sunrise-Douglas development without harming the Cosumnes River.

According to Mike Eaton, director of TNC's Cosumnes River Project, they reached this conclusion "without any analysis of ongoing or cumulative impacts or potential future impacts on surface water systems. They literally ignored it."

The environmental impact report, California's equivalent of a federal environmental impact statement, considered the possible detrimental impacts of increased groundwater pumping on practically everything, except stream flow in the Cosumnes River. According to UC Davis hydrology professor Graham Fogg, "I can't say for sure that this development will have a significant impact. I'm saying that the developers and county planners haven't done their homework to find out."

The third threat comes from Omo Ranch Resort, which sought approval from the California Water Resources Control Board to divert surface water from the middle fork of the Cosumnes River for a golf course. Jeff Mount's research team reviewed the proposal and concluded that the diversion would significantly increase the number of low-flow days, double the number of days that the river was dry, impede fall-run Chinook salmon passage to the spawning grounds and adversely affect salmon survivorship.

The low flows would expose eggs buried in spawning gravels. The low-oxygen and high-temperature conditions would kill many of the developing eggs. Low-flow periods in the spring might retard fingerlings from migrating to the ocean; lower flows would certainly increase the time needed for fingerlings to move from the spawning beds to the estuary, which would increase their vulnerability to predators.

The most critical problem facing the Cosumnes is that California law for the most part fails to regulate groundwater pumping. Existing pumping has already lowered the water table beneath and adjacent to the Cosumnes. Lent Ranch Marketplace and the Sunrise-Douglas development will worsen the situation.

Think of the Cosumnes River basin as a gigantic milkshake glass, with each well representing a straw in the glass. California law allows new straws to be added without requiring new development to remove (or pinch) existing ones. So it is likely that Lent Ranch Marketplace and the Sunrise-Douglas development will go forward because they would pump groundwater, and California law is indifferent to groundwater pumping. Omo Ranch Resort, on the other hand, poses less of a threat because, as it would rely on surface water, the developers must obtain permission from the California Water Resources Control Board.

According to a hydrologic model prepared by Jeff Mount and his UC Davis colleagues, restoring flows in the Cosumnes would require a reduction in current levels of pumping by approximately 190,000 acre-feet per year. No one thinks that will ever happen.

But a glimmer of hope comes from a fall 2001 proposal by the UC Davis team to divert surface water, as little as 50 cfs (12,000 af) between September and December, from the American River through the Folsom South Canal, which crosses the Cosumnes, and discharge it to the Cosumnes itself. This modest amount of water would significantly improve flow.

Although more than one-half of this augmented flow would seep into the ground, it would pre-wet the channel before the fall rains, thus increasing the amount of precious rainwater retained within the river's channel. It might provide just enough water for the Chinook, thereby winning the "game of inches."