River health: Finding fixes
In part I, The Why Files described the growing evidence that rivers around the world are under attack by overuse, overfishing, pollution, damming, diversion and invasive species.
Amid growing concerns about a shortage of freshwater, the damage shows up in terms of declining biodiversity and widespread ecosystem damage.
On Oct. 8, 2010, Newsweek magazine summed up what it called a “global freshwater crisis”:
As rivers are dried, dammed, polluted and fished to within an inch of their ives, environmental needs, inevitably, take second place to human water requirements. Wetlands — essential to flood control, fish and birds—are drained or diked off. Dams store water but prevent fish from spawning and inundate floodplains. Dams and levees channelize and regulate rivers so barges can travel, blocking the natural oscillation of water levels and destroying wetlands. And some water diversions are so huge that they prevent rivers from reaching the sea.
It’s a spiral of decline. Pollution, demand for freshwater and over-fertilization injure rivers, which in turns harms groundwater and freshwater on the surface. Environmental damage reduces our long-term supply of fish and freshwater, and over-use of water and related resources boomerangs back to cause environmental harm.
The use and abuse of water is all about cycles, and actions taken to help the environment can help freshwater resources, and vice versa.
Light at the end of the (water) tunnel?
As The Why Files looked around at proposals to reduce damage to rivers, we noticed that many projects are trying to bring nature back to rivers and watersheds.
These proposals and projects are intended to:
Faced with a succession of floods, a few American towns have headed for higher ground. In the late 1970s, for example, Soldier’s Grove, Wis., abandoned its riverside site after repeated flooding. In May, 2010, nearby Gays Mills, also on the Kickapoo River, received a $4.4 million grant to do the same, and construction of housing and businesses has begun on higher ground.
Dams are a major source of environmental trouble on rivers, and their removal is becoming an accepted restoration tactic. Although we could not find an international number, the conservation group American Rivers says more than 600 dams have been removed in the United States during the past 50 years.
Disarming the dam! River liberation
River engineering and ecosystem alteration are a fact of life on the Mississippi River and its major tributaries, where levees hem rivers into narrow channels. Although most of the Mississippi floodplain in Wisconsin and Minnesota is in nature refuges, half of the river’s floodplain has been drained and diked in Iowa and Illinois. And according to Richard Sparks, director of research at the National Great Rivers Research and Education Center, 90 percent of the floodplain has been drained and leveed in the state of Mississippi.
Above St. Louis, the U.S. Army Corps of Engineers owns dams spaced about 20 miles apart, which it uses to control water level, essentially creating a barge canal on the iconic river.
Dams and levees have sundered the river from its floodplain, which served as a home of plant and animal biodiversity and a relief valve during spring floods. Because the Mississippi carries a heavy load of sediment, that stable water level has left a thick layer of muck in sloughs along the river.
If the water level can resume its normal undulation—rising in spring and falling in fall – the yucky-mucky can be restored to wetlands inhabited by the plants and native animals that evolved to live in that varying habitat.
Restoring these wetlands is the goal of an agreement that the Corps has negotiated with fish and wildlife agencies. The Corps is adjusting dam operation so the water level falls during summer, allowing native plants to recolonize shorelines, to the benefit of migratory waterfowl and other animals. “By adjusting the control, they are having biologically measurable effects,” says Sparks, “although it does cost a little more because the Corps has to dredge areas where sediment accumulates.”
The water level may fluctuate by just half a foot near Minneapolis, and up to three feet near St. Louis, but even this smidgeon of variation is allowing hundreds of acres of wetlands to return to some of the “reaches” between dams, Sparks says. “Sediment along the shoreline can dry out and compact during summer, so when it’s reflooded, there’s less sediment to be resuspended; it’s a cumulative effect.”
Leavening the levee! Wetland watershed
The catastrophic Mississippi River flood of 1993 — when broken levees flooded millions of acres — caused a rethinking of the role of levees in the river and its major tributaries. Still revered as essential protection for cities and farms, levees are also recognized for making floods taller and more dangerous.
Because levees also divide rivers from their floodplains, some conservation groups want to convert floodplain farms back to wetlands. On the Illinois River alone, conservation organizations have bought out three agricultural levee districts, Sparks says. The goal is to reconnect these areas to the river, “and attempt to recreate a water regime that mimics a more natural flood pulse.”
At Emiquon Preserve, thousands of acres of corn and soybean are being turned into wetland, upland prairie and forest by the Nature Conservancy. Between them, the Conservancy and the U.S. Fish and Wildlife Service own about 14,000 acres on this part of the Illinois River, says Doug Blodgett, director of river conservation at the Illinois Conservancy.
Instead of removing the levee, the Conservancy has recreated wetlands by shutting down pumps that once dried the farmland behind it.
Removing the levee would expose the wetland to the disturbed hydrology of the watershed, where the water level naturally fell in summer and, as in the Mississippi, fostered plant growth and soil consolidation. Low water in late summer is no longer reliable, Blodgett says, “Because we have destroyed the upland wetlands, changed prairies into row crops, channelized streams, put in parking lots and roofs, and so the river no longer behaves naturally.”
The water flow has been so altered, Blodgett says, that some land along the Illinois is “nearly devoid of plants, especially submerged aquatics.” Simply removing the levees today “would nearly wipe out the plant community that we are trying to restore.”
Once the Army Corps builds gates in the levee, however, they will be opened when the river is behaving normally. “That would let critters move back and forth, so the plants and wildlife can return to the river,” Blodgett says.
Restoring the natural wet-and-dry cycle to the floodplain benefits the native plants and animals that evolved to live there. for example, mussels are among the most endangered species in North America, and Blodgett notes that “The Illinois River had the most productive mussel beds in North America, and that was due to the backwaters like Emiquon.”
Emiquon is already seeing a surge in rare pumpkinseed sunfish, spotted gar, horned grebe, and American white pelican. The threatened red-spotted sunfish was recently introduced, and the Conservancy and its partners plan to rear starhead topminnow, weed shiner, emerald shiner, and iron color shiner. (We don’t know much about these fish, but don’t they have gleaming monikers?)
Attitudes about floods, levees and rivers are changing, says Sparks, who has spent decades studying big Midwestern rivers. “Today, there is a better understanding on the part of the public, decision makers and conservation organizations, of what a floodplain river is. This pulsing is normal, and flooding up to certain point is good. When you said ‘flood’ 25 years ago, the immediate reaction was, ‘How do we stop it?'”
Loving the locks! Fish rodeo in the Southeast!
Dams on the Pacific Northwest are infamous for blocking the upstream spawning journeys of salmon, but the problem is widespread. Along the Gulf of Mexico, for example, the Jim Woodruff Lock and Dam on the Apalachicola River has blocked the threatened gulf sturgeon and the Alabama shad, a prolific, base-of-the-food-chain fish.
The Alabama shad, which used to occur as north as far north as Illinois, is “taking a nosedive nationwide, barreling toward official listing as threatened or endangered,” says Steve Herrington, Nature Conservancy’s project manager for the Woodruff Dam project. The inability to reach spawning grounds is a major cause of decline.
Dynamiting the dams would be unpopular and expensive, but when conservationists in the Southeast looked to help the shad, their found solution in the lock itself. “Could we move fish like we move boats?” Herrington says.
After all, when spawning time approaches, the fish naturally swim upstream — until they slam into the dam. Would it be possible to corral those fish into the lock, lift them to Lake Seminole, and allow them to continue their upstream spawning journey?
Adapting techniques previously used to help American shad migration in Maine, Pennsylvania and South Carolina, a broad group of conservation agencies, scientists and conservationists, and the Army Corps of Engineers, devised a plan to open the lock to migrating fish.
The fish rodeo occurs twice a day during spring, the spawning season.
The key is an artificial waterfall — a fancy term for a stream of water. “These are natural cues, and this bit of splashing seems effective,” Herrington says.
A stream just below the lock attracts the fish, then the lock opens, and a second stream lures the fish further inside. After the lower door closes, the lock fills, and within about an hour, the upper door opens, releasing a new cargo of Alabama shad and gulf sturgeon into Lake Seminole, and then into two rivers that supply the lake.
After five years, the collaboration has proven that it can move fish, says Herrington. “The fish we tag are moving 100 miles, through good habitat, until they bang into the next dam” on the Flint River.
Data from the Georgia Department of Natural Resources provides “strong circumstantial evidence” that the effort is also bolstering populations of the shad and the sturgeon, Herrington adds. “They are almost certainly spawning in the Flint River due to the fish passage.”
The Why Files had to mutter that the fish rodeo sounded too good (and too cheap!) to be true, but Herrington reminded us that the fish are just doing their thing. “If you have acres and acres of good spawning habitat, which we do, then all the things we know about fish biology say this is what we would expect to see.”
Aside from buying a pump and some PVC pipe from a bigbox retailer, the only cost is to open and close the lock, Herrington says. “We are trying to be really simple; we want to keep cost down to nothing.”
Crushing concrete! Reviving an urban river
During the 1960s, Milwaukee’s Kinnickinnic River was converted to a concrete ditch, useful for flushing rainwater quickly into Lake Michigan, but with no biological value. The concrete ditch, intended for flood control, further reduced the watershed’s porosity and prevented surface water from entering the groundwater.
Impervious watersheds are closely linked to a variety of river deficits, says Thomas Chapman, an engineer with the Milwaukee Metropolitan Sewerage District (MMSD). “There are studies galore that show that the minute a watershed starts getting over just 10 percent impervious, the impacts are seen, and at 25 percent, it’s a significant impairment,” says Chapman. “Most of our urban areas already have that.”
The combination of fast runoff and slow infiltration starves groundwater and washes pollutants and abnormally warm water into Lake Michigan. Meanwhile, the concrete “river” quickly parches between rainfalls.
The sewerage district also needs to reduce runoff because storms overwhelm its treatment plants, which accept both stormwater and sewage in 10 percent of its service area, and a few times each year untreated sewage can flow into Lake Michigan during heavy storms.
Ideally, Chapman says, restoring natural processes should reduce runoff into the lake, slow the storm surge, and allow incoming wastewater to be treated.
The desire to slow runoff, speed infiltration, improve esthetics and recreation and allow natural processes to clean river water have motivated the MMSD to fund a return to more natural conditions along the Kinnickinnic and Menomenee Rivers in Milwaukee.
Contractors have started obliterating the first 1,000 feet of concrete on the Kinnickinnic, says Chapman, and 84 homes are being purchased for recycling and removal. Eventually, MMSD will remove about three miles of concrete along each river, to create a 200-foot wide stream corridor — essentially a park with esthetic and biological value. “These are paved stream with no aquatic life, with garages lined up to the edge of the concrete,” Chapman says. “They are drainage ditches, kids would float through in heavy storms, and there were some tragedies.”
Milwaukee has good experience busting concrete. In 1997, the city removed the North Avenue dam on the Milwaukee river, Chapman says. “I’ve had people tell me fly fishing along the Milwaukee river is gorgeous. Who would have thought that we would get tourist dollars because we removed a dam? You lose the perception that 1,000 feet away is a high-density urban area…”
Getting organized! Australia responds to long drought
In Australia, the driest continent, the water problem is all about shortage. But after a decade-long drought, the continent-nation has learned something about water management. In fact, when they are pressed for an example of enlightened water management, water experts often cite Southeast Australia’s Murray-Darling river basin, home to one-third of the country’s agriculture, two million people, and the only two major rivers.
Faced with a long drought and caught between thirsty cities, parched farms and drying wetlands, the basin could be the stage for a water war. Instead, it is the site of advanced water-allocation by the Murray Darling Basin Authority.
The crisis has been put to good use, says Bradley Udall, a specialist in western U.S. water resources at the University of Colorado. “Frequently a water crisis brings out some very novel, innovative solutions that prior to the crisis was politically unthinkable. All sorts of interesting opportunities arise, because lots of people want to do the right thing, and are freed from political constraints.”
The authority favors transparency and provides online access to the current storage situation in itsreservoirs.
Because surface- and ground-water are both over allocated, the authority is producing a new plan, with plenty of public input, to align demand with supply.
Udall says Australia’s response to the persistent water shortage also includes:
Like a hanging in the morning, the 10-year drought, with the accompanying wildfires and economic dislocations, have concentrated minds in Australia, Udall says. “Changes have gone on in politics, policies, infrastructure, conservation, agriculture and the economy, they have all kinds of solutions on the table that prior to the drought would have gone nowhere.”
The language used to discuss water reflects the changes, Udall says. “They use the term ‘water security’ over and over, and they use ‘security’ the way we use ‘national security.’ It’s a reflection of how seriously they take their water problems.”
As Udall indicates, nothing could be more dangerous than taking freshwater for granted. How will the rest of the planet respond to the growing freshwater shortages?
– David J. Tenenbaum
Terry Devitt, editor; S.V. Medaris, designer/illustrator; Jenny Seifert, project assistant; David J. Tenenbaum, feature writer; Amy Toburen, content development executive
- Communities and Dam Removal. ↩
- Emiquon preserve. ↩
- Water security resources. ↩
- International Rivers. ↩
- American Rivers. ↩
- River Network. ↩
- Measuring success of river restoration. ↩
- EPA: urban river restoration initiative. ↩
- Economic impacts of river protection and greenways. ↩
- Clearinghouse for dam removal information. ↩
- Biggest dam removal in U.S. ↩
- Restoring Milwaukee’s urban rivers. ↩