Read more about the work at Nine Eagles and Slip Bluff, and other water quality successes, in Working For Clean Water, the DNR's annual watershed success story publication.
Improving water quality is not an overnight success or a quick fix. It takes time, but it can also be sustained over the long haul – which two southern Iowa lakes have shown over the last decade.
In the early 2000s, efforts began to improve the lakes in Nine Eagles State Park and Slip Bluff (County) Park in Decatur County. Both lakes were struggling with excessive sediment clouding the water, and both lakes had the unique opportunity that most of the lake’s watershed lies within park boundaries.
At Nine Eagles, the DNR constructed new sediment retention basins to catch and filter sediment before it could reach the lake, and work on trails and in forested areas aimed to reduce erosion in the first place. Slip Bluff’s efforts focused on cutting back erosion in wooded areas of the park and along the shoreline, using basins and structures to trap sediment and riprap to hold the shoreline in place.
The efforts reduced sediment delivery to Nine Eagles Lake by 85 percent, which improved water clarity to where you could see almost 6 feet down in the water. At Slip Bluff, sediment delivery was knocked down by 64 percent and resulted in a 50 percent improvement in water clarity. They were Iowa’s first two DNR watershed improvement efforts recognized nationwide by EPA as success stories.
The most recent water clarity reading done at Nine Eagles by DNR Fisheries staff was 95 inches – meaning you could see almost 8 feet down in the water. Add in aquatic plants and work to bolster bluegill and crappie populations, and Nine Eagles is a great place to reel in a fish.
“Nine Eagles has a high abundance of aquatic vegetation, which helps improve water quality and provides fish habitat,” says Andy Jansen, DNR fisheries biologist, noting good fishing for largemouth bass and redear sunfish at Nine Eagles, and good crappie and largemouth bass fishing at Slip Bluff.
“The water quality has held up very well,” says Richard Erke, director of the Decatur County Conservation Board, of Slip Bluff. “There are aquatic plants growing along some of the shoreline and you can still see 8 to 10 feet down. Fishing has increased a little and we have had an increase in people paddling the lake in canoes and kayaks.”
Additional work to maintain woodlands, reduce invasive species and encourage native plant growth has also helped control runoff by filtering runoff and absorbing it before it can reach the lake, Erke added.
Bud Taylor, park manager at Nine Eagles, echoes Erke, noting that park use has increased since the improvements, especially with swimmers. “Heavy rains would muddy up the water with silt and it would take weeks to clear up,” said Taylor in 2005, after the project’s completion. Now, he adds, “I get a lot of comments about how clear the water is – you can see the bottom of the lake in some places.”
