A lake's revival in western Minnesota
Not everyone appreciates the sandbars and mud flats being exposed as the waters of Marsh Lake are purposely lowered. Yet wildlife managers are excited by what they see. The vegetation sprouting on these newly exposed areas is the very foundation for what they hope to accomplish here.
We stood atop the new control structure for Marsh Lake as winds whipped down the lake and chocolate-colored water raced through gates below our feet.
A middle-aged man made a beeline to us. “Thank you for this (expletive) mudhole,” he said sarcastically. It’s ruined the walleye fishing, he growled before stalking off.
The man’s words were directed at our host, Walt Gessler, wildlife manager for the Lac qui Parle refuge with the Minnesota Department of Natural Resources. Had the man chosen to engage in a conversation with Gessler, he would have learned this: Gessler had arrived at this spot some days earlier and happened upon people illegally pulling walleyes from the lake with dip nets.
A project now underway to restore the lake in the upper reaches of the Minnesota River in western Minnesota has not harmed the walleye population, and in fact is aimed at improving the numbers of game fish in this lake, he explained.
The cause of the man’s ire and comments are easy to see: Approximately 1,500 acres of lake bottom have now been exposed along the perimeter and in the shallow bays of the 5,100-acre lake. Where the angry man saw mud, Gessler and other wildlife managers see the very foundation for reviving the Marsh Lake eco-system.
The waters of Marsh Lake are being purposely drawn down by the new control structure that has replaced the fixed crest dam that created the lake in the 1930s. As the waters have dropped, sandbars and mud flats that have been submerged for decades are exposed.
A dry spring has aided the effort. The current lake level is now similar to what it was in the drought of 1976, said Gessler. The lake is low enough that a fish passageway added at the lake’s outlet to the Minnesota River as part of the $13 million restoration project was not running as Gessler led reporters on a tour last week.
But the Pomme de Terre River, restored to its natural outlet to the Minnesota River downstream of Marsh Lake, was running at a steady, work-horse like clip.
Gessler said he likes what he sees happening on the newly exposed sandbars and mud flats. Smartweed and river bullrush are sprouting on the sandbars, and river willow is taking hold too. Rush and cattails are covering the mud flats. By summer’s end, much of this cattail will be shoulder height, Gessler pointed out.
“It’s responding quickly,” said Gessler of the vegetation. The mud and sand bottoms of the lake are nutrient rich, “absolutely loaded” with the phosphorus that has been washed into the lake with sediment over the past decades.
Until this draw down, these newly exposed areas were covered by only a couple of feet of water. They held mostly carp, which kept the bottoms churned and murky and essentially devoid of any vegetation. The last survey of the lake completed by the DNR found “not a speck of vegetation,” said Gessler as he led the way over the newly exposed bottom of a bay near the Louisburg Grade. “In a 5,000-acre lake, that’s not good.”
The draw down mimics a drought, and allows vegetation to sprout again. The emergent vegetation is the base of the food pyramid, said Gessler. It will host a rich diversity of invertebrates that will become the feed for fish and wildlife as water levels rebound.
By lowering water levels, the draw down should also help submergent vegetation to reestablish itself in the lake.
Sago pondweed and other submergent plants filled the lake when water levels rose after the dry years of 1976 and 1988. The waterfowl hunting that followed “was really, really good,” said Gessler.
While the wildlife manager knows that the emergence of mudflats and sandbars are the cause of consternation for some, he also hears from those who already appreciate the benefits they provide. This spring saw thousands of migrating shorebirds arriving to take advantage of them. He ran into one group of birders who were positively “giddy” by the shorebirds they observed, he said.
He was also pleased to report that the draw down has not adversely affected the large pelican rookery on islands on the lake’s north end. He said researchers reported that nesting numbers continue to look good.
While these are all positive signs, Gessler knows that the changes now taking place also interfere with how we use this area. Waterfowl hunters will have more difficulty reaching parts of the lake due to the lowered water levels this fall, he pointed out.
A team with the US Corps of Engineers, Minnesota DNR and the watershed district is monitoring the draw down. It will make decisions on when to allow water levels to rebound, and when to conduct future draw downs. It’s going to be a learning process, said Gessler.
He cautions that we should not expect instant results, but he is confident — from what he already sees happening — that fish, waterfowl and other wildlife will definitely benefit. That means everyone from birders to anglers and hunters have more to look forward to, given time. “Once we put water back in the system and (with) all that vegetation, it is going to be pretty cool,” he said.