REGIONAL— Minnesota’s iconic natural grain is slowly disappearing and shallow lake managers, both state and tribal, are continuing to puzzle about the factors behind the increasingly apparent decline of manoomin, or wild rice.
It’s a problem that’s been weighing on those who manage as well as harvest the grain from the state’s many wild rice lakes and river stretches for more than a decade, as research and ongoing management techniques have been slow to yield a clear picture of the factors behind the decline.
Those concerns intensified last year, which was the worst year for wild rice in more than a quarter century across northern Minnesota. While poor seasons are considered “resting” years for wild rice, some lakes that long produced regular crops appear to have gone to sleep altogether and researchers aren’t sure why that is happening.
“It’s very frustrating,” said Melissa Thompson, shallow lake specialist with the Department of Natural Resources’ Tower area office. “We’re trying to hard to do something and understand what’s going on, but we’re not seeing the response we’ve been hoping for.”
Thompson has overseen several years of management efforts on Big Rice Lake, north of Virginia, long the region’s largest and most productive rice lake. That changed about 25 years ago and after years of experimenting with water levels on the lake, the DNR with cooperation from Fond du Lac tribal managers began using an airboat with specially designed vegetation cutters to “mow” expanding areas of pickerel weed and other aquatic vegetation in hopes of re-establishing rice beds that once thrived across the 2,000-acre lake. Pickerel weed, which forms dense mats that wild rice can’t easily penetrate, and other perennial aquatic vegetation, like water lilies and watershield, have been increasing in abundance on many wild rice lakes and as those plants have become better established, wild rice abundance has declined.
Fond du Lac has spearheaded efforts to combat the perennials and began using boats with cutters to try to beat back their spread on several wild rice lakes, but with inconsistent results.
That’s been the case, for certain, on Big Rice. “The cutting we’ve been doing with the DNR and Fond du Lac has definitely decreased pickerel weed, but it’s been slow to see any response from the rice,” said Thompson.
Thompson said Fond du Lac is now working with the University of Minnesota to see if the lake’s nutrient cycle has been affected by the persistent cutting of the pickerel weed, which has left a considerable amount of organic material on the lake bottom. “We’re hopeful that as that decomposes, the nutrients will become more available,” she said.
It’s potentially a race against time. While studies have suggested that wild rice seeds can remain viable for up to 20 years, it’s been that long since the last strong rice crop on Big Rice. According to survey work completed by the 1854 Treaty Authority, Big Rice produced an average of 189 grams of wild rice biomass per square meter annually between 1998 and 2005, the first eight years of their survey. During that stretch, 2004 saw the lowest production at 117 grams per square meter, although that rebounded to 151 grams in 2005. By the next year, however, the lake produced just 21 grams of wild rice biomass per square meter, and it’s averaged just 18 grams annually in the 19 years since. In 2003, it hit an all-time low of just four grams.
Little Rice Lake, which is connected by stream to Big Rice, has seen a similar decline. As recently as 2004, wild rice biomass on the lake hit 112 grams per square meter, but that has fallen steadily since and last year bottomed out at just 0.01 grams.
While a few popular ricing lakes in the region have maintained relatively steady productivity in recent years, other lakes, like Round Island and Stone, have seen similar declines, to the point where rice has nearly disappeared.
Pollution an unlikely factor
While the impact of sulfate pollution from the mining industry and other sources have been much in the news in recent years, sulfate is clearly not the cause of the decline of wild rice in many of the top rice lakes, since most are quite remote and are unaffected by mining or other pollution discharges.
Naturally, most waters in northern Minnesota are very low in sulfate, with levels typically under two milligrams per liter, a concentration that is unlikely to impact wild rice. The Minnesota Pollution Control Agency, back in 1973, established a strict sulfate standard for discharges into wild rice waters of 10 mg/l, but agency officials never enforced the rule until pressure from the state’s tribal leaders and the Environmental Protection Agency forced them to do so.
A decline driven by
climate change?
The drop in wild rice productivity, and its virtual disappearance on many lakes, including some in the Boundary Waters Canoe Area Wilderness where pollution can’t be a factor, has many fearing the problem is a more intractable one— the rapid warming of the climate due to increasing levels of carbon dioxide, methane, and other greenhouse gases in the atmosphere.
“I think the climate is part of what’s a play here,” said Thompson. While wild rice has long competed with perennial native plants, those plants often struggled to take hold on many of the shallow rice lakes, where severe winters frequently froze out the roots of the plants, continually setting them back and allowing the wild rice, an annual that reseeds itself each year, the advantage. Thompson said she fears that warmer winters may be tipping the scales in favor of the perennials, which gradually out-compete the wild rice. “There is some research that shows rice does better after harsh winters,” she said.
Warmer winters may not be the only way that climate change is impacting wild rice. All across the world, including here in northeastern Minnesota, summer storms are bringing more rainfall than ever and sharp increases in water levels, particularly at certain stages of the rice plants’ development, can uproot the growing stalks. Many rice managers believe the major flood event in June 2024, which sent flood waters into area lakes and streams, was at least partially responsible for last year’s wild rice bust.