Illinois river islands taking shape

October 02, 2011 at 02:32 PM

The first few steps on land are akin to walking a finely-packed sandy beach - a slight give under the boot, yet firm.

But further steps onto the more freshly silt-filled bags making up the perimeter of an island being constructed on the Lower Peoria Lakes of the Illinois River are more like walking on a waterbed - soft and spongy.

“It’s kind of squishy still, as you can see,” said Anthony Heddlesten, an environmental engineer for the U.S. Army Corps of Engineers, describing what just over a year ago was settled and submerged under brown Illinois River waters.

Already, more than 70,000 cubic yards of silt and river soil have been dredged from the lake bed just north of the McClugage Bridge, and with some ingenuity, pumped into 60- and 100-foot-long special “geotextile” bags forming the outline of a 21-acre boomerang-shaped island. In fact, its border can be seen online from satellite images using Google maps.

In the perimeter alone is nearly enough dredged silt to fill both of Downtown Peoria’s Twin Towers. An equal amount has been excavated into the middle, with about three times that volume still to go to complete the center. A jetty, made up of rock will then be placed at the north end of the island which, weather permitting, is expected to be complete in 2012.

The project, one of three islands proposed for the Peoria Lakes, is more than 15 years in the planning, now about two years in the making. It is being built to restore depth diversity primarily for fish habitats.

“When it’s all complete, eventually what we hope to see is a deep water habitat,” said Heddlesten, who has been assigned the Peoria Lakes project the last two years. “The perfect scenario is that years from now we will see ice fishing shacks covering this whole area during the winter.”

While river navigation channel depths remain deep - averaging 8 to 15 feet deep but ranging to more than 20 feet deep in parts - outside the channel, the average depth runs only 1 to 2 1/2 feet deep.

“The problem is 100 years of sediment flowing into and sitting in the lakes,” said Marshall Plumley, a regional technical specialist also with the Corps of Engineers. “We’ve lost all that habitat to sediment.”

Annually, about 12 million tons of sediment is delivered to the Illinois River, with about half discharged into the Mississippi River and the other half settling into Illinois River backwaters and lakes, according to state estimates.

Still, Plumley said the island projects are not aimed at improving navigation of the river.

“This whole issue of what to do with the sedimentation in the lakes, that’s what got the ball rolling on this (island) project a long time ago,” Plumley said. “We had to start somewhere. This is not meant to solve sedimentation in the lakes, it was just the most cost-effective way to restore depth and the habitat value (versus dredging and shipping it somewhere else). The alternative is to do nothing and the trend of the decline in the ecosystem continues.”

In fact, Plumley said there is much restoration work that needs to take place in the watershed and elsewhere to address siltation.

For the East Peoria island project, Congress has appropriated funding, which combined with some state money, totals $8.1 million.

With a proposed second and third islands south of the McClugage Bridge, a total of about 200 acres of the Peoria Lakes would be dredged to between 6 and 8 feet deep, if not more - depths not seen in decades - creating three islands spanning 75 acres.

No money has been set aside for the additional islands, though $400,000 of the $600,000 needed to plan and design them has been appropriated.

When complete, the first island’s crown will rise some 10 feet above the water, though at times it may be submerged, depending on season and river levels.

The special material being used to hold the silt allows water to slowly seep out but is dense enough to retain the soil, leaving firm ground in place after some time. Eventually, the material will degrade, leaving behind the new ground.

The Corps does have a history with building islands, mostly on the Mississippi River, but also finishing one on the Illinois River next to Chillicothe in 1994. “It did have a deep water habitat component,” Plumley said. “The project has performed well.”

Already, grasses, trees and other vegetation have taken root on the new banks at the East Peoria island. Animals, mostly shorebirds such as gulls but also waterfowl including ducks, geese and the occasional crane also already have taken refuge there at times. Turtles have been spotted on the new shore, as well as raccoon prints.

“Will one island do the job? It will help, but it won’t fix the problem alone,” says Russ Crawford, president of the Heartland Water Resources Council and chairman of the Peoria Lakes Basin Alliance, local groups whose goal is to preserve and protect the Peoria and Pekin lakes and water basin.

They have backed the island as one of the solutions to removing the sediment.

“Unfortunately, the problem is so large, a one dimensional solution won’t cut it,” Crawford continued, adding that watershed restoration and land management such as erosion control practices are required to prevent further siltation.

The groups also favor projects like the mud-to-parks initiative that saw Illinois River silt used to cover a Chicago brownfield. Though because of the great moving expense the groups also would like to see some form of marketing of the silt, with hopes private business would go in and remove it. That would serve to create commerce as well as alleviate government and taxpayers of the expense.

Crawford said the island project removes the sediment, creates habitat on the island for birds and animals, and creates deep-water habitat near the island for increased quantities and species of fish. He said the newly dredged area, by increasing the depth, also means more area for recreational boating use, better travel along the river and sets the stage for further river improvement projects.

But not all favor the island project near the McClugage Bridge.

The Heart of Illinois Sierra Club historically has not approved.

Joyce Blumenshine, the group’s conservation chairperson, said they have opposed the island’s construction based on the price tag and because it doesn’t address the root cause.

“It doesn’t deal with the siltation,” Blumenshine said. “Until you deal with the problem, you’re going to keep spending millions upon millions to deal with this. It’s a Band-Aid approach.”

And Taura Edwards, daughter of late environmentalist Tom Edwards, has circulated a petition to stop the work, saying the project, like the Sierra Club asserts, does not address the problem. Moreover, she claims it essentially is eliminating water surface area.

Bill White, a geomorphologist with the Illinois State Water Survey, on the other hand has long called for construction of additional islands and creation of a secondary channel on the east side of the Peoria lakes, which he says would speed up the water and move sediment along before it has a chance to settle here.

“If people want open water and access to keep marinas open, in my opinion that’s the only way to do it,” White said of a secondary channel.

To create the secondary channel, however, White said the second set of islands must be built to provide a framework.

“At the same time, we fully recognize we must greatly reduce the sediment,” he stressed, noting 40 percent of the silt in the Peoria lakes comes from local tributaries. “Of course, there is never enough funding to fund these large-scale projects,” he said.

All agree additional work must be done to reduce sedimentation.

Plumley said the Corps has identified three particular tributaries among 10 in a 2007 comprehensive plan that are significantly contributing to siltation: Senachawine Creek near Chillicothe, Tenmile Creek near East Peoria and Crow Creek West further north in Bureau County.

Engineers are just beginning to look at the approximately 25-mile-long Senachawine. The state and local landowners have taken some steps to reduce erosion.

The Illinois Department of Natural Resources program to provide subsidies to landowners to plant trees and vegetation to reduce erosion and a separate, smaller initiative through the state’s Department of Agriculture have proven beneficial, White said.

“There is good evidence showing that it’s working,” White said, though some funding for those programs have been reduced.

Others agree there has not been adequate funding for restoration and conservation initiatives.

Plumley said past estimates to address all of the Illinois River Basin, approximately 33,000 square miles and hitting three states, would cost some $7.5 billion - which he said is a similar amount spent to address issues in Florida Everglades across an area about one-sixth the size of that identified here.

The average volume lost due to sedimentation of all backwater lakes since 1903, along the Illinois River, is at 70 percent, according to the Illinois State Water Survey, with some approaching 100 percent.

“The degradation of the Illinois River is pretty profound,” Plumley said.

Dave Haney can be reached at 686-3181 or .(JavaScript must be enabled to view this email address).