Dam Removal

Today the notion that dams are not sacred monuments to be preserved for all time is universally accepted by state and federal agencies. As yet, however, there is no such acceptance by the general public, a fact that should alarm all thinking Americans regardless of how they feel about fish and wildlife. A dam's average life expectancy is 50 years, and a quarter of America's 76,000 dams defined by the Corps of Engineers as "large-" or "high-hazard" (in which failure is apt to kill people) are more than 50 years old. By 2020 the figure will be 80 percent.

Impoundments behind large dams, most of which are unlikely to be removed in the foreseeable future, can stratify and take on the ecological features of genuine lakes. But most impoundments are mongrels, possessing neither riverine nor lacustrine characteristics; and while they may support organisms that evolved in both environments, they support neither well. For example, in Wisconsin--which leads the nation in dam removal—anglers caught smallmouth and largemouth bass in the impoundments above the four dams on the Baraboo River, but the fishing was pretty lousy.

When the last of these dams was removed in February 2001 (making the Baraboo the longest river freed by dam busting in the nation), both bass species, as well as catfish, walleye and sauger, surged back in numbers that astonished even state biologists. Crews from the Wisconsin Department of Natural Resources had shocked 11 fish species above the Waterworks and LaValle dams, the dominant one being carp. Eighteen months after the dams were taken out the crews shocked 24 species above the remains of the Waterworks dam and 26 species above the remains of LaValle, and in both cases the dominant species was smallmouth bass. Before the demise of the Waterworks dam the crews had shocked three smallmouths; 18 months after removal they shocked 87. Recovery has barely gotten underway and already the unshackled Baraboo's smallmouths are drawing national attention. Although smallmouths may thrive in lakes and large reservoirs, they do best in rivers because that's where they evolved. Largemouths evolved in still water; but they're doing far better in the free Baraboo than they were in the impoundments because they're no longer suppressed by carp.

Of course, there would be no recovery of Baraboo gamefish without recovery of the complex ecosystem of which they are part. In the tepid, eutrophic impoundments midges, sludge worms and bloodworms had dominated benthic fauna. Now caddisflies and mayflies dominate cool, oxygenated riffles newly cleansed of sediment. With the species sought by anglers have come lake sturgeon, paddlefish, darters and the giant native sucker called bigmouth buffalo—all moving freely, breeding in restored habitat, feeding gamefish with their eggs and fry. And with all the fish have come mussels which, as larvae, migrate through the system by temporarily attaching to fins and gills.

Today the energy flow of the freed Baraboo is increasing geometrically from Hillsboro to the Wisconsin River, through 120 miles of mainstem and up into hundreds of tributaries veining the slopes of the 650-square-mile basin, out and up into meadow, muskeg, forest and sky--to the muskrats that eat the mussels, the owls, weasels, bobcats and wild canids that eat the muskrats, to the otters, eagles, ospreys, herons, kingfishers, turtles and snakes that eat the fish, to the salamanders, frogs, bats and woods warblers that eat the clouds of aquatic insects. Dam removal is about life, not death, rebirth not destruction.

The Prairie River, which in 1944 produced Wisconsin's record inland brook trout of nine pounds, 15 ounces, was arguably the best trout stream in the state. Now, released from its four dams, it's fast regaining its former status. The Prairie Dells dam, nine miles from the river's confluence with the upper Wisconsin, had been rebuilt for hydro power in 1904 when it was already 24 years old. But power generation never happened because the engineer had stuck a decimal point in the wrong place. Once the dam was finished there was no reason to waste perfectly good turbines on it, so for 87 years it did nothing except collect sediment, block fish and otherwise unravel the rich, river-based food chain.

In 1991, when the dam was taken out, the 2.6-mile-long impoundment regurgitated 20,000 cubic yards of muck, discoloring the river for miles. Dam defenders shrieked; environmentalists cringed. But three seasons of snowmelt flushed the system clean. Brook trout reproduction jumped 30 fold, and the state quit stocking hatchery fish.

Pennsylvania has done nearly as well as Wisconsin. When the state Fish and Boat Commission removed a dam on Lititz Run, water temperature dropped 12 degrees in 24 hours. Lititz Run is a tributary of the Conestoga River which had been a limestone trout stream before dams turned it into a series of stagnant, methane-belching sumps. Now, with the removal of 20 dams in the system, water quality has improved to the point that the state can stock hatchery trout, and the goal of re-establishing self-sustaining populations is no longer a pipe dream. Already American shad, moving up from the Susquehanna for the first time in a century, have reproduced.

The benefits of dam removal had been no secret before all the good work in Wisconsin and Pennsylvania, but the lessons went unheeded by a large segment of the public. Restoration of the Baraboo was plenty contentious. Pennsylvania had an easier time on the Conestoga, although the Fish and Boat Commission's Scott Carney wishes the state had more angler support. "The biggest challenge we face is trying to restore stocks like shad that haven't been fished in anyone's memory," he told me. "Getting anglers excited about fishing for something they have no experience with and trying to justify taking out an impoundment they've fished their whole lives can be challenging."

Local resistance was downright nasty during restoration of the Prairie River. The last dam to go was the 21-foot-high, 675-foot-long Ward Dam at Merrill, built in 1905. It had been producing $34,000 worth of electricity per year and costing the owner, International Paper, $50,000 a year to operate. Moreover, it was riddled with cracks, and test borings into the concrete produced pure powder for the first 16 inches. DNR proclaimed it a safety hazard and ordered International Paper to either rebuild it or tear it down.