Mysteries of the not-so-deep

More than 50 interested community members came together Tuesday evening for a twilight tour of the Twelve Mile and Three Mile Lake watersheds in the area of Union County north of Afton.

Local experts spoke to the group during a guided tour on issues including water quality, local environmental conditions and the importance of maintaining the two lakes for recreational use and tourism.

Participants learned about the Twelve Mile Lake wetland, visited renovated sites at Three Mile Lake, learned about techniques farmers are using to minimize soil runoff and toured the facilities of the water treatment plant near Twelve Mile Lake.

The Union County Soil and Water Conservation District hosted the event, in partnership with the USDA and NRCS.

A twilight tour like this had been held only once before, in an invitation-only event for state and local government officials.

“We wanted to highlight and promote the conservation work that is ongoing in the Three (Mile Lake) and Twelve (Mile Lake) watersheds, and how it impacts the water quality in the lakes, but also our drinking water,” said Union County District Conservationist Kayla Creek.

What is a watershed?

The term watershed is often used interchangeably with “drainage basin,” or “catchment.”

In short, it is the area of land (and water) that drains all the streams and rainfall to a common outlet, such as a river, or, in this case a lake.

The type of land-use and structures on a watershed directly affect its downstream outlets in a variety of ways.

This is why the Union County Conservation Board, the Iowa DNR and the Union County Soil and Water Conservation District (among other partners) came together about 5 years ago to conduct something called a “watershed assessment,” in which the health of the watershed was evaluated.

A watershed management plan was developed, and state and federal funding was applied for to begin conservation practices and constructions.

Roughly $909,000 of funding was raised, and then used over those five years in the Twelve Mile Lake watershed to install eight grade-stabilization structures, eight water and sediment control basins, 94,575 feet of terraces, 17 acres of waterways, 15.87 acres of stream-side filter strips and 331 acres of new Conservation Reserve Program (CRP) land within a half-mile of Twelve Mile Lake.

Initial assessments, before renovations, showed an average of 4,320 tons of sediment and 5,616 pounds of phosphorus (which in excessive amounts can result in undesirable algal growth) per year delivered to the lake.

After installing these practices, the amount of sediment and phosphorus reaching Twelve Mile Lake is expected to be reduced by 3,719 tons per year, and 4,837 pounds per year respectively.

Three Mile Lake and the Three Mile Lake watershed also received more than $200,000 in renovations over this period.

“All the players in the community came together so well,” said Iowa DNR Mount Ayr Fisheries Technician Dray Walter.

“It’s amazing the teamwork we have in this corner of the state,” said Walter. “That’s the beauty of this part of Iowa — it’s just the people willing to work with you. And it makes it a whole lot easier.”

Why renovate at all?

The Twelve Mile and Three Mile Lake watersheds serve as a kind of filtration barrier to upstream sediments and pollutants.

Before these pollutants and sediments are allowed to enter the lakes, these practices serve to filter and retain them in conservation installments like dikes, wetlands and ponds in an effort to keep the lakes clean, clear and deep.

Cleaner, clearer lakes mean cleaner drinking water and better recreation.

While Twelve Mile Lake was historically regionally known for its top-class fishing, decades of introduced pest fish have diminished its water quality. And, though the lakes’ financial value added to the local Union County economy by tourism dollars is estimated near $13 million annually, that number could be much higher.

“Two of the main fish in southwest Iowa that attack our fisheries are common carp and yellow bass,” said Walter, “and Twelve Mile (Lake) had both of them.”

The Iowa DNR Fisheries Management office for Ringgold County’s eight-county area is based out of Mount Ayr. They are responsible for ensuring quality fishing in the lakes, ponds, rivers and streams of their coverage area.

“I started (with the DNR) in 2003,” said Walter, “and there was a lot of water throughout southwest Iowa that we had gone through and renovated. And when I first started, it was like pulling teeth to go in and renovate a lake, but over time we developed a reputation on rebounding these fisheries faster.”

Walter said that Twelve Mile Lake was the 21st or 22nd renovation he’d been a part of.

“We’ve poured everything we had into this,” said Walter, “from what we’ve learned from past renovations.”

Walter detailed the process the DNR used in rehabilitating Twelve Mile Lake for better fishing, which included temporarily drawing down the water level by 17 feet to control for carp and yellow bass, installing upstream filtration measures like filter strips and grass waterways and placing cedar and concrete fish habitats in the lake to promote spawning and provide angling hotspots.

The DNR has also been busy raising fish for stocking the lakes in area hatcheries, including blue catfish, walleye fingerlings, bluegill and adult bass. Only one other lake in the state of Iowa, DeSoto Bend along the Missouri River, stocks blue catfish.

“We’re pretty excited with what we’re doing here — there’s a lot of firsts. I’m hoping to see a lot of fishermen out here next year,” Walter said.

Doug Jones, director for the Union County Conservation Board, expects these hopes to be realized.

“As soon as we took care of those carp,” said Jones, “the water quality just came back almost immediately, and we got vegetation growth back, so we’re really excited about the renovations.

“So we like the lake,” said Jones. “We love the lake. It’s our bread and butter for what we do here for recreation, so anything that happens in that watershed affects what we’re doing down here. We like clean water and so do the users.”