Rivers are a precious (priceless?) commons, defined by the public trust doctrine as common public resource. Yet in North America and around the world, the doctrine of Manifest Destiny has degraded rivers and the watersheds they drain.
Irrigation poisons much of the world’s arable land with salt. Deserts expand as clear-cut logging and overgrazing erode soil and shift rainfall patterns, and log drives scar floodplains for decades or centuries. Mountains disappear into the jaws of strip-mining machines to produce coal that fuels the electric grid. Oil and gas pipelines disrupt animal migrations.
Offshore oil-rigs tear apart the fragile habitats of the ocean floor, and thousands of birds and ocean creatures die in inevitable oil spills. Power generation, industry, agriculture, “car culture,” and the by-products of war release toxins into the soil, air, and water that accumulate in living things, causing deformity and disease in humans and animals. Dams disrupt the delicate hydrological processes of rivers, robbing deltas of their silt and upper tributaries of their spawning salmon. This devastation cannot be separated from the standard of living in postindustrial countries. It has been woven so tightly into the fabric of our lives that it has become invisible.
In the American West, the water wars have not ended. In the late 1980s, a Colorado ranching community went to court and successfully blocked the transfer of the San Luis Valley’s water to Albuquerque. As the twenty-first century opened, the Winneman Wintu tribe—who saw most of their original reservation disappear under Lake Shasta’s waters—began fighting a Bureau of Reclamation plan to raise Shasta Dam as many as two hundred feet, thereby drowning remaining sacred sites and lands. In the last three decades, however, river restoration projects—often initiated by indigenous communities and ordinary citizens—have flourished on degraded rivers, mostly in industrialized countries.
River restoration manipulates feedbacks between fluvial (that is, a river’s flow and sediment movement) and ecological systems to assist the recovery of hydrological function and ecological productivity lost to dams, channel modification, water diversion, and land use change. To create restored channels in dynamic equilibrium with flow regime and sediment flux requires three types of understanding. First, how do contemporary flow patterns and sediment movement affect how a river’s channel changes through time? Second, how did rivers look and function before major human changes? Third, what major disturbances, both natural and anthropogenic, affected past channel evolution? Are rivers still adjusting to this disturbance?
Most daunting are basin-scale initiatives like salmon restoration efforts in the Columbia and Sacramento watersheds. Because salmon inhabit a river from tributary to estuary, restoring the salmon runs introduces complex and controversial issues such as dam removal or modification and the reservation of water for in-stream use. For basin-scale river restoration to become politically viable, smaller-scale projects must demonstrate efficacy, long-term resilience to natural disturbance, and social and economic benefit.
Despite several decades of small-scale effort—and a few major projects like the Kissimmee River restoration in Florida’s Everglades or the CALFED partnership to restore California’s Sacramento and San Joaquin rivers, there's scant consensus on how to turn a sterile and mutilated floodplain back into a functioning river. The $10 million Milltown project on Montana’s Clark Fork River (link to High Country News article) exemplifies the re-engineering approach, where crews will bulldoze a new channel after Superfund contractors remove tailings. But some river experts say we should devote more of the $2 billion spent yearly on U.S. river restoration to understanding how rivers like the Clark Fork work. Then we can take action that may not require re-engineering.
Sometimes excluding livestock from riparian areas, or removing key levees and dams to restore flood patterns and sediment movement, is enough to permit degraded rivers to heal themselves. River experts point to Oregon's Sandy River, which quickly washed accumulated sediment downstream after Portland General Electric blew up Marmot Dam last fall. Coho salmon swam past the dam the day after it was breached, and spawning habitat has greatly improved.
River restorationists disagree about whether we can return rivers to health by constructing stable, static channels. "Restoration cowboy" Dave Rosgen says that carving a single, sinuous channel across a river's old path jumpstarts restoration. In the 1980s, in response to 75 years of Army Corps of Engineers "fixing" that straitjacketed thousands of river miles for flood control and navigation, Rosgen came up with a straightforward method for evaluating and redesigning streams. His techniques are now used by agencies from the U.S. Department of Transportation to the Forest Service.
But many geomorphologists, who study how rivers shape the landscape, fault Rosgen's method for using a simplified template instead of a detailed study of how rivers move sediment. They note that river channels evolve in a complex interplay of water flow and the bounce and skid of waterborne sand and gravel. Although the Rosgen method is based on the notion that river channels are stable, aerial surveys show they wind across landscapes unpredictably. Old meanders yield to new meanders, to oxbows, and often intermittently to braids. Season to season, year to year, few rivers stay in the same place. In fact, over-simplifying complex rivers can lead to catastrophe, scientists warn. On Cuneo and Uvas creeks in California, costly Rosgen-inspired reconstruction projects blew out during small floods in 1996 and '97.
The bigger issue in restoration, though, isn't single channel versus multiple threads; most rivers left alone will display sections of both. Rather, it's the question of strict human control over the intricate and gradual patterns of natural processes. Over-controlled rivers stop functioning, some scientists say, becoming what Colorado State University geomorphologist Ellen Wohl calls "virtual rivers," because floods and crucial processes like beaver damming and log jamming are thwarted.
Beavers evolved with North American rivers and is largely responsible for their pre-European settlement flows. Beavers by instinct follow the prime directive of process-based restoration: You can't make an instant river. What you can do is provide ample detritus and room for the river to wander and recreate its own stability and health. In the late 1990s, the Zuni Fish and Wildlife Department in New Mexico relocated 23 beaver to a reservation stream. Within three years, the beavers built a series of dams that raised the water table, flooding out invasive tamarisk and regenerating the willow forest. On Utah's Provo River and California's Cosumnes River, flood-control levees cut off the rivers from their floodplains. Over the past decade, state agencies have purchased floodplain land, then breached the levees. On the Cosumnes, native fish populations rebounded, flood risk declined, and willow and cottonwood survival has improved. Breaches and multi-thread channel reconstruction on the Provo show similar improvements.
Despite their success, such long-term strategies are generally out of sync with government funding cycles. Finding money to buy floodplains is difficult, so single-channel reconstruction "quick fixes" predominate.
Our predecessors streamlined crooked streams with dynamite and built thousands of dams. Now, some scientists and restoration practitioners envision a new kind of stewardship wherein we modify infrastructure to survive wildfires, droughts, and floods, then let natural processes take their course. But on most Western rivers, the dams, railroads, highways, and floodplain development that constrict river floodplains will remain. River restoration design will simply have to adapt.
We view watershed restoration a social, economic, political and ecological project that requires collaboration and compromise from rural landowners, urban residents, tribes, scientists, agencies, and people who use a watershed for recreation, subsistence, and livelihood. Riparian and wetland areas support high species diversity and provide “ecosystem services” such as flood protection, improved water quality, and nurseries for bird and fish. Renewing river processes blocked by dams, water diversion, and levees—floods, sediment movement, and the ability of a river to change course—is important, even essential, to restoring healthy rivers, riparian areas, and wetlands. We believe that restoration projects must consider the entire watershed—and the divergent priorities of its human residents—in order to renew the dynamic ecological and physical processes that constitute healthy rivers. We envision a new restoration paradigm that supports workers in the woods and on farms and ranches and benefits fishers, boaters, nature lovers, and water users alike.
Strategies for restoring healthy watersheds
- Get to know your local creek, river, pond, lake, beach, wetland, or estuary. Spend time there alone, with friends, and with kids and neighbors.
- Visit the source of your drinking water and the waterways impacted by the farms that grow your food.
- Support and participate in watershed-based restoration projects. Join or start “Friends of [insert name of local waterway here]”.
- Support farmers and ranchers working to protect riparian areas on their lands.