feature
Restoring For restoration projects to succeed, comprehensive
knowledge about ecosystems must be strengthened. JANET PELLEY
River ecosystems range in size from small streams to the vast Everglades. Leading ecologists view current efforts to restore and save these systems as flawed and too little too late.
quatic ecosystem restoration is big business, with large projects garnering substantial federal funding. The repair of the Florida Everglades tops the list, with nearly $8 billion in state and federal funds. But most projects are flawed, scientists say. And although the Clinton administration's Clean Water Initiative sets out a mandate for restoring 1000 watersheds, success is not guaranteed: A failure rate of as high as 60% in some parts of the country shows that many restoration projects are based on weak scientific foundations, say the experts (i). Part of the problem, according to Bob Beschta, a forest hydrologist at Oregon State University in Corvallis, is that restoration science is just too new yet to have produced long-term studies that can elucidate die complexity of river processes, forms, and
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mation on how a river functions ecologically and physically or why it is degraded, says Kondolf, who can cite many examples of this "cookbook" approach that have failed in California (2). Obstacles to restoration come together in an especially sticky way in the Grand Canyon area of Arizona. Large rivers, such as the Colorado River, which runs through the canyon, may be impossible to restore, says Jack Schmidt, a geography professor at Utah State University in Logan. On the Colorado River, and on nearly all other large rivers in the country, dams constrain restoration of their full range of water and sediment flow. Moreover, in the Grand Canyon, says Schmidt, "Invasion of non-native species has potentially irreversibly altered the native ecosystem." He notes that managers face an especially tough dilemma in attempting to restore natural flood patterns to the Grand Canyon reach of the Colorado River below Glen Canyon dam. Although floods are crucial
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ecological relationships. "We will never know how much restoration is enough to meet the objectives at the beginning of a project," concurs Brian Richter, director of the freshwater initiative at the Nature Conservancy. This is why adaptive management— treating restoration projects as continually monitored and adjusted ongoing experiments—is such a major growth area, Richter says. But public pressure that favors funding tangible results, such as river enhancement structures, rather than funding research has led to ineffective or even harmful projects, say Richter and Matt Kondolf, a professor of environmental planning at the University of California-Berkeley. Because restoration has a connotation of rebuilding, there is a tendency to engineer structures, such as rock weirs in impaired streams, says Jack Stanford, an ecologist at the University of Montana. "That philosophy has failed, and failed miserably," he says. Richter believes some of the blame for these failures can be laid on practitioners with little scientific training who have extended a popular channel classification scheme—hydrologist Dave Rosgen's system—beyond its credible use to guide restoration projects. Rosgen is principal hydrologist with Wildland Hydrology Consultants in Pagosa Springs, CO. The system, which classifies rivers based on topography, substrate, and flow, does not yield infor© 2000 American Chemical Society
dangered native fish they could v/ipe out an endangered snail and bird that moved in when the Glen Canyon dam eliminated flooding
Let the river do the work "The key to restoring aquatic ecosystems is recognizing that their integrity depends on their natural dynamic character," says LeRoy Poff, an ecologist at Colorado State University in Fort Collins. The magnitude, frequency, duration, and timing of water flow limit the distribution and abundance of aquatic species and regulates the ecological integrity of the system, he explains (3). Stanford agrees: "What you need to do is create a natural flow regime. There are so many dams in this country, and a dammed river can't do its work." According to Will Graf, a geomorphologist at Arizona State University in Tempe, there are 75,000 dams more than six feet high in the United States, which together are capable of storing a full year of runoff from the entire country. By altering the hydrologic cycle, they have a huge impact on ecosystems; getting consensus on removing or lowering them is a challenge, Graf notes. According to Schmidt, the Colorado River flooded frequenuy before Glen Canyon dam was built in 1963, often carrying huge volumes of water (at flow rates of 2150 m3/s) and huge sediment loads (60 billion kg/yr). The steep river bed and periodic high flows FEBRUARY 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 8 7 A
At the Nevills site along the Colorado River in the Grand Canyon, the March 1996 controlled flood Beach/Habitat-Building Flow event created large sand deposits along the river, which can be seen by comparing the (top) before and (bottom) after scenes of the flooded area.
rich in sediment combined to give the river its distinctive bare sand bars found downstream from rapids. These conditions also led to the evolution of a group of fish found nowhere else in the world that are adapted to an environment of frequent flooding, high turbidity, and water temperatures ranging from 29 °C in summer to 0 °C in winter. Damming the Colorado River has extirpated three of these eight fish species from the canyon; two are endangered; and reproduction by the remaining native fish is significantly reduced, Schmidt says. Glen Canyon dam provides nearly complete flood control, virtually eliminating sediment discharge below the dam and maintaining river water temperature at a cool 8-10 °C. The water is now too cold in the summer for native fish to spawn, and the habitat for young native fish has declined. It has, however, created ideal conditions for introduced trout, 8 8 A • FEBRUARY 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
which compete with and prey on the native species, Schmidt notes. "The river now looks completely different than it did before the dam," he says. Debris slides have narrowed rapids—they don't get washed out by floods—and large sand bars, no longer replenished by sediment, are eroding. Stream sides that would have been scoured by flooding before the dam now support marshes and extensive stands of salt cedar, an invasive exotic tree. This new vegetation provides federally proposed critical habitat for the endangered southwestern willow flycatcher and Kanab ambersnail, which did not live in the canyon before the dam (4). Their presence poses a dilemma for the Adaptive Management Workgroup, the federal advisory committee of government, environmental, tribal, and sport fishing representatives that is managing the river. According to Schmidt, mimicking floods and water temperatures of predam conditions will benefit native fish, but it will harm the endangered bird and snail, as well as the valued trout fishery (see photos at left). "It's a matter of values to decide what to do, but they won't take the courageous step of choosing some resources over others," Schmidt contends. "We can choose a flow regime with a temporal scope to optimize management for all these resources," counters Larry Stevens, a consulting ecologist in Flagstaff, AZ. Hydrologists, engineers, and ecologists are working on a river ecosystem model (5) to predict the responses of species to different flow regimes. Stevens suggests this model will help managers design and time floods to benefit native fish species but not disturb the ambersnail and southwestern willow flycatcher. However, Dick Marzolf, chief of the branch of regional research with the U.S. Geological Survey (USGS), asserts that "nobody has devised a model to adequately describe biotic responses, because the complexity of the ecosystem is not understood." Careful timing and control of managed floods could be implemented, but the monitoring required to document responses is beyond present understanding and resources, Marzolf says. Engineering nature in the Everglades "You can't engineer optimal conditions that will benefit an entire ecosystem," Poff says. There is no one optimal flow level that will maintain a range of conditions for all species, he contends. For instance, he observes, in a natural system, all species may be adapted to year-to-year fluctuations in conditions, but only some species will do well in dry years, whereas omers will mrive well only during wet years. Furthermore, restoration projects are usually targeted at a few key species, a focus that could leave other unknown species vulnerable to declines, he says. Nonetheless, this is the approach being tested in Florida's Everglades. Nourished by a broad sheet of water that spilled over the southern rim of Lake Okeechobee and into Florida Bay, the Everglades once covered most of southern Florida, says Stuart Pimm, an ecologist with
Columbia University's Center for Environmental Research and Conservation in New York. But the natural amount and seasonal timing of the flow, which used to be dry from December to May and wet during the hurricane season from June to November, "has been dramatically altered to satisfy the demands of urban growth and agriculture," Pimm says. An intricate system of 1000 miles of canals and 720 miles of levees now controls flooding and drains rich muck soils south of Lake Okeechobee that produce sugar, oranges, and much of the nation's winter vegetables, says Mike Slayton, director of government affairs for the South Florida Water Management District in West Palm Beach, FL. Launched in 1949, the Central and Southern Florida Project has helped supply land and water for the area's 6 million residents. It has also reduced the Everglades to half its original size, cut water flows to the existing Everglades by 70%, and slashed populations of wading birds, such as egrets and ibis, by almost 95% (6). Altered water flows, habitat fragmentation, invasive species, and nutrient pollution endanger 68 species with extinction, says Pimm. Wading birds rely on the seasonal cycle of water, nesting during the dry season to take advantage of shallow pools that concentrate fish. The canals divert 1.7 billion gallons of water per day to the Atlantic Ocean and Gulf of Mexico. As a result, during dry years, pools vanish and birds can't get enough to eat, he notes. Pimm and colleagues (7) have shown that too much water at the wrong time endangers the Cape Sable seaside sparrow by flooding its nests. The sparrow builds its nest in grass a few inches above water during the dry season. "When wetland conservation areas north of the park are drained to make room for the approaching wet season, you get massive flooding in the Everglades when it's supposed to be dry," he says. Public protest over the widespread species declines led Congress in 1992 to authorize a study of what could be done to reverse the downfall, according to Don DeAngelis, a research ecologist with USGS. A subsequent $8 billion 20-year plan submitted to Congress in July 1999 by the Army Corps of Engineers, the South Florida Water Management District, and 30 other federal and state agencies "is the flagship case of ecosystem restoration," DeAngelis says (6). The plan aims to "capture most of the freshwater now flowing unused to the ocean and gulf and to deliver it when and where it is needed most," explains Slayton (see related story, ES&T 1998,32 (23), 533A). About 80% of the reclaimed water will go to the ecosystem; the other 20% will be dedicated to human use, including 6-9 million new area residents expected by 2050, he says. According to Slayton, the scheme "employs the latest technology that has never been used on this scale." Projects include removing 240 miles of levees and canals, elevating parts of the Tamiami Trail highway to allow water to flow through it, and constructing 40,000 acres of filtration marshes to purify and store agricultural runoff. Aquifer storage and recovery, one of the newest technologies described
in the plan, will ring Lake Okeechobee with 200 wells that can inject fresh water into the Floridan aquifer for storage and withdraw it when needed, Slayton explains. What constitutes restoration? It's easy to say that the goal of restoration must be to restore an ecosystem's function, but it's harder to say exactly what this means, DeAngelis asserts. For the Everglades, one measure of restoration success is maintenance of viable populations of key species that are at the tops of food chains or have specialized diet and habitat needs. If the various species are increased in number as a result of proposed manipulations of the water regime, "this would be a strong indication that the restoration plan is effective in restoring ecosystem function," he says. DeAngelis coordinated an effort at Many restoration five universities to use mathematical projects in models to project the responses of six California have groups of species, including Florida failed because they panthers and the haven't been based Cape Sable seaside sparrow, to differon an understanding ent water regulation schemes. The of geomorphological researchers developed comprehenand ecological sive ecological landmodels that processes. combine a hydrologic model that describes water depth —Matt Kondolf, University on a day-bv-day baof California-Berkeley sis a Geoeraphic Information Svstem vegetation man and m n H p I c t h a t Hocr*riVio tl-ii=» prir*
ulation dynam'ics of the key SDPHPS fffl For instance the simulation can calculate how nianv off spri g the Cape Sable sparrows hp ahlp to
produce in any year for a given water regime, DeAngelis says. For each species, the result is a colorcoded map of South Florida showing good and bad areas. You can visually see on a landscape level how i
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notes. Although DeAngelis stresses that the current state of science is insufficient for making predictions of the exact number of each species 30 years from now, he argues that the models do show that the restoration plan now before Congress should result in substantial improvement of key species over what would be expected if nothing is done by the year 2050. Notwithstanding any improvements that might be realized, a group of leading ecologists, including Pimm, Stanford's Paul Ehrlich, and Harvard's E. O. Wilson, complained in a March 1999 letter to Interior Secretary Bruce Babbitt that the plan does too little too late in the way of restoration. The aim should be to restore the natural sheet flow of water as much as
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possible and reverse the ecosystem fragmentation, Pimm asserts. Instead, "half of the plan is about water management for the benefit of the people of South Florida," he says. Pimm points out that although the plan proposes removing seven miles of one of the area's major canals, it also proposes building 200 additional miles of canals and dikes to manage storage and supply of water, further contributing to fragmentation. "As an ecologist, you want a system that is natural, alive, and healthy, not one that is fragmented and managed on life support," he concludes. Babbitt responded to the scientists' concerns by establishing a National Research Council Advisory Committee. The panel comprises 16 scientists who will review the plan and make recommendations on program goals, data, monitoring needs, and engineering projects, says Steve Parker, director of the Water Science and Technology Board at the council. The plan still awaits congressional hearings and approval.
Promoting adaptive management According to Kondolf, many restoration projects in California have failed because they haven't been based on an understanding of geomorphological and ecological processes (2). In addition, he says, opportunities to learn from past mistakes have been lost, thanks to little or no evaluation and monitoring after the project is in place. Although most people don't understand the principles of adaptive manageA s an ecologist, you ment—treating each restoration project as an w a n t a system t h a t is experiment, then monitoring to improve future natural, alive, and projects—Kondolf and healthy, not one t h a t others are working to insert them into the Bayis f r a g m e n t e d and Delta program California's biggest restoration managed on life project. Launched in 1994, the support. Calfed Bay-Delta Program to restore the Sacramento-San Joaquin —Stuart Pimm, watershed in California Columbia University, has been hailed as the New York most ambitious ecosystem recovery effort of its kind in the world (9). The mission of the 30-year state and federal effort is to achieve recovery of endangered native species by rehabilitating natural processes and simultaneously enhancing water SUDply and reliability for agriculture use and h u m a n consumption. The Sacramento and San Joaquin Rivers empty into a delta on San Francisco Bay, forming the largest estuary on the West Coast. Once a vast maze of channels, wetlands, and ponds, it has been fundamentally altered by massive reservoirs and diversions over the past 60 years. Depending on rainfall, 20-70% of the natural flow is diverted. The delta now comprises islands of farmland surrounded by levees and export pumps that lift water over the Tehachapi 9 0 A • FEBRUARY 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
Mountains to thirsty southern California. The watershed supplies drinking water for two-thirds of Californians and irrigates more than 7 million acres of farmland {10). At one time, 2-3 million chinook salmon spawned in the system each year along with large numbers of steelhead trout. But habitat loss due to dams and flow alterations, pollution, encroachment of salty bay water, and introduction of exotic species have put the steelhead and salmon at risk of extinction, says Peter Kiel, a consulting environmental scientist in San Francisco, CA. The nearly $2 billion plan to restore some ecosystem processes in the 61,000 square-mile watershed received a boost last year from an independent group of scientists who drafted a strategic plan based on adaptive management (10), says Kondolf. An example of how this should work is going forward on the Tuolumne River, where the La Grange dam and the levees below it have limited the lifegiving floods on the Tuolumne River, he notes. The gravel supply critical for salmon spawning is trapped behind the dam, and gravel mining in the streambed has created minilakes of warm water that support exotic largemouth bass, which eat young salmon, Kiel observes. Some years, returns of fallrun chinook have been fewer than 100 fish, says Jennifer Vick, a geomorphologist with Stillwater Sciences, a consulting firm in Berkeley, CA. Restoration of physical and ecological processes is based on the idea that "the river knows best," Kiel says. The aim is to reconnect the river with its flood plain, says Vick. Kiel notes that this approach is projected to rebuild in-stream habitat, such as cut banks, flush out fine sediment that smothers fish eggs, and water the floodplain to restore streamside shrubs and trees. Setting back levees to allow the river to flood should also provide fish with floodplain food sources and create a refuge from high flood velocities in the channel {10). Filllng the in-stream gravel pits wiil absorb more than $30 million of the total $200 million project cost. The scientific studies that preceded design of the plan, as well as provisions for monitoring, "show that restoration can be done in a way that helps people learn," Kiel says. "This is the kind of restoration we want to do, to make a river healthy again, but we can't afford to do it on every stream," he laments.
References (1) Kondolf, G. M. Environ. Manage. 1995,19 (1), 1-15. (2) Kondolf, G. M. Aquat. Conserv. Mar. .reshw. Ecosyst. 1998, 8, 39-52. (3) Poff, N. L. BioScience 1997, 47 (11), 769-784. (4) Schmidt, J. C, et al. BioScience 1998, 48 (9), 735-747. (5) Conceptual Model. Grand Canyon Monitoring and Research Center, www.gcmrc.gov (accessed Oct. 1999). (6) Central and Southern Florida Project Comprehensive Review Study, www.restudy.org (accessed Oct. 1999). (7) Curnutt, J. L., et al. Anim. Conser. 1998, 1, 23-32. (8) DeAngelis, D. L., et al. Ecosystems 1998, i , 64-75. (9) Calfed Bay-Delta Progrrm—Strategic PlanforEcosystem Restoration; Calfed Bay-Delta Program: Sacramento, CA, ,9999 (10) Calfed Bay-Delta Program—Revised Phase II Report; Calfed Bay-Delta Program: Sacramento, CA, 1998.
Janet Pelley is a contributing editor of ES&T.
