Fish and wildlife managers put "more teeth" in southwest's Heron Lake

For the fifth time in as many decades, Heron Lake in far southwestern Minnesota has a revamped natural resource management plan.

New in 2022 for this historic waterfowl basin will be a heavy emphasis on fish-stocking — namely walleye and northern pike. Are duck hunters OK with that?

In short, yes. But it took some explaining from Maggie Gross, the shallow lake specialist who helped finalize the management plan this month for the Department of Natural Resources.

"We need more teeth in the water," Gross said.

Systematically adding predatory fish will sharpen the DNR's attack against the destructive carp, bullheads and fathead minnows that overpopulate the lake, she said. Since the early 1900s, those quick-to-multiply rough fish have stirred up the bottom and wiped out natural beds of wild celery and other plant food. When the food disappeared, so did the once-thunderous clouds of migratory ducks and geese that made Heron Lake one of North America's most productive waterfowl rest stops.

Gross said stocking predatory fish in Heron Lake isn't new to the DNR, but it hasn't been done with frequency. She said duck hunters, including some who belong to century-old private clubs on the lake's north side, balked at the idea during early discussions. But Gross said the pushback softened when the DNR provided new wording to emphasize that the agency would be stocking walleyes and northerns for the sake of wildlife, not to create a recreational fishery.

"We wanted a more comprehensive plan on how we were going to tackle the rough fish in Heron Lake," she said.

Coupled with intentional water drawdowns in the lake, the overarching purpose is to foster the growth of aquatic vegetation. Sustaining plant life in Heron Lake won't only feed ducks, but it will cleanse the water. The growth of aquatic vegetation helps lower farm runoff pollution from suspended sediments and excess nutrients.

Gross said the new plan calls for periodic fish stocking, especially in conjunction with water drawdowns. According to the plan, the drawdowns will produce fish kills and mimic drought conditions that allow plant seeds time to germinate. Replenishing the lake with walleyes and northerns would allow them to eat the larvae and the babies of rough fish when water levels return, stunting their reproduction.

"We primarily want to really ramp up those stocking efforts if we achieve a drawdown," Gross said.

Michael Mooney, chairman of Delta Waterfowl Foundation and a member of Heron Lake Farms hunting club, said the new focus on fish-stocking raises the danger of strengthening Heron Lake's constituency of anglers. That's why it was important for the DNR to emphasize the management plan's intent, he said.

"It's a good plan and a start, but we need to do more," Mooney said. "I couldn't be happier with the start."

Also new to the management plan are automatic triggers for when the DNR should draw down the lake. According to the plan, water clarity will be the most important measure. Even at that, DNR officials foresee only one intentional drawdown every eight to 10 years.

Located in farm country near the bottom of a large watershed loaded with agricultural drain tile, Heron Lake has suffered from runoff pollution. Less than 3% of land in the watershed is preserved as grassland, according to the DNR.

The management plan applies to North Marsh, North Heron and South Heron — designated together by the DNR as a wildlife lake. Including Duck Lake, the entire basin is about 8,000 acres in size. It has an average water depth of 2.9 feet and a maximum depth closer to 6.5 feet, according to the DNR.

The new management plan doesn't offer a solution for the drainage issue, but Gross said the agency will work with "local partners" to promote best management practices on the land to "improve the quality of water flowing into Heron Lake."

Albert Henning, a farmer who is president of the Jackson County Conservation League, said it's hard for area landowners to join government-funded land conservation programs because the area's land is valued so highly for agricultural production. Good farmland in the watershed sells for $11,000 to $12,000 an acre, sometimes more, he said.

But he is optimistic that more state-funded buffer strips — vegetative borders around waterways — will be forming in the near term to mitigate runoff. He said it's "part of the upgrading." He also cautioned that there's no turning back the clock on farming's importance to society or its dominance in the region.

"It's never going back to 20-acre farming," Henning said.

The upgrades in the DNR's new management plan include a major repair of the outlet for Heron Lake, the so-called State Dam. The dam's 40-foot hydraulic gate is currently inoperable because the hydraulic cylinders that raise and lower the gate need replacement. Gross said the DNR has hired an engineering company to explore options to fix it. The cost of repairs could exceed $200,000, but the structure is vital for accomplishing drawdowns of the lake.

"This is a high priority for the DNR and we hope to repair the State Dam as soon as possible, but we do not have an exact time line yet," she said.