KEEP OKOBOJI BLUE ~ Arnolds Park, Iowa

Keep Okoboji Blue ~ Arnolds Park, Iowa

Dickinson County's Diamond Lake to be restored

DNR, Ducks Unlimited partnership will revive shallow prairie lake
By Greg Drees, Journal correspondent - Sioux City Journal

ARNOLDS PARK, Iowa -- Long known for its chain of Iowa Great Lakes, Northwest Iowa is also home to a wealth of shallow prairie lakes that exist within ecosystems of their own.

Over the years, however, these water bodies have lost much of their allure through degradations in the watersheds and other inter-lake problems. But hope for their rejuvenation may soon be on the horizon.

At a meeting on Thursday night at the Iowa Welcome Center in Arnolds Park, the Iowa Department of Natural Resources (DNR) announced a pilot project in partnership with Ducks Unlimited aimed at restoring the 143-acre Diamond Lake in northern Dickinson County.

Mike Hawkins, a fisheries research biologist with the DNR stationed in Spirit Lake, said Diamond Lake and many like it in the region have degraded because of changes in hydrology, wetlands losses in the watershed and sedimentation and nutrient loads due in large part to agricultural practices. At its completion, Hawkins said, the project should restore vegetation to Diamond Lake, return a viable fish population and -- most critically -- improve water quality.

The Diamond Lake watershed encompasses 1,618 acres. The lake is situated on a public land site of more than 300 acres managed by the DNR. The restored uplands on Diamond Lake's periphery provide wildlife habitat and recreational opportunities for hunters, bird watchers and nature lovers. Hawkins said the lake restoration project should once again make the environment more suitable for fishers, duck hunters, canoeists and kayakers.

"Water quality is the driving force behind the project," Hawkins said.

The three-year restoration begins this spring with a prescribed draw down of the lake, which has a current maximum depth of less than 6 feet, to about one-and-a-half feet. That process will promote a winterkill of the rough fish population -- dominated by common carp and fathead minnows -- and begin a compaction and oxidation of the sediments in the lakebed, which should reintroduce bulrushes, cattails and other aquatic vegetation to the system.

Hawkins said an outlet construction should be completed by the spring of 2007, at which time a fish barrier will be placed downstream to prevent rough fish from re-entering the lake. The draw down will continue through the winter of 2008 and the refilling process will begin that following spring. Restocking of the lake with yellow perch and northern pike will occur in the spring of 2009.

"This is a long-term management plan," Hawkins said. "We're looking at a 20-year blueprint, and if we see the water quality begin to degrade again during that period, we will once again conduct a draw down of the lake."

It is possible that four draw downs could occur during that span. "Once again, water quality is the main objective here," Hawkins said. "With good water quality comes a good fishery and increased wildlife diversity."

Without engineering costs, which will be borne by Ducks Unlimited in partnership with the DNR, the project is expected to cost about $150,000. Hawkins said a successful project at Diamond Lake would likely spur similar restorations on other shallow lake environments in the region.