Two lakes along Minnesota's border with Canada will have new water-level guidelines for the first time in nearly two decades.
The International Joint Commission signed an order in March to implement new rule curves - which dictate the daily minimum and maximum lake levels - which are expected to reduce flood peaks and boost the ecology in Rainy and Namakan lakes. The commission, a joint American and Canadian entity that manages air and water issues along the border, has used rule curves to manage water levels since 1949 via dams at Kettle Falls between Namakan and Rainy and at the west end of Rainy Lake near International Falls.
The IJC's order also calls for improved communication and relationships with Native American bands regarding water issues.
Additionally, the order will expand the ability for the International Rainy-Lake of the Woods Watershed Board's Water Levels Committee to implement an alternative Rainy Lake rule curve or request the IJC deviate from Namakan Lake's rule curve if the winter and spring conditions could lead to a high flood risk.
"What we tried to do with this overall study and plan is to balance everybody's needs, balance impacts to the environment, balance impacts to fisheries, property owners, power generation - balance everybody's needs so it doesn't maximize any certain species, but overall has a good general balance over all those different interests," said Scott Jutila of the U.S. Army Corps of Engineers, who serves as an engineering advisor to the Water Levels Committee.
ADVERTISEMENT
The IJC's order was the culmination of several years of work by a binational rule curves study board, which analyzed the effects the rule curves implemented in 2000 had on the lake system and gathered input through dozens of public hearings and meetings. Prior to 2000, the rule curves hadn't been changed in 30 years.
Namakan Lake's rule curve implemented in 2000 made "dramatic improvements" to the lake's ecology because the previous rule curve was causing "severe drawdowns" in the water level during winter, which was then affecting spawning and access to the lake for spring fishing, Jutila said. Rainy Lake's rule curve was largely left alone in 2000.
However, as a result of Namakan Lake's change in 2000, Rainy Lake has seen a slight water-level increase of about three inches during extreme conditions, he said. When they began meeting with area residents and studying the effects the 2000 rule curve had on the lakes, "one of the big concerns on Rainy was that affect of just a few inches - affected docks, affected shoreline, affected resorts," he said.
The new rule curve for Rainy Lake mitigates that increase by allowing the Water Levels Committee to determine whether there is a high flood risk and then implement an alternative rule curve that keeps Rainy Lake's water level lower for a longer period of time in spring, he said.
In addition, the new rule curves are expected to help control invasive species.
Invasive hybrid cattails use the same habitat of shallow water near the shoreline as wild rice - essentially pushing the wild rice out. Regulating water levels is one way to help create a more natural balance between the two, he said. The committee considered allowing more severe fluctuations in water levels, but that would affect spawning and cause flooding. Instead, the new water levels will encourage muskrats, which are good at keeping cattail populations under control.
"We changed the rule curve for winter months so that we would have less of a drawdown and then we expect that will allow muskrats to overwinter and help to control the hybrid cattails," he said.
The higher water levels during winter are also expected to help fish who spawn in the fall.
ADVERTISEMENT
"The drawdown that we had over the course of winter had a negative impact on those spawning species because it dried up the spawning beds during winter. With this less severe drawdown, we should have a positive impact on whitefish and cisco," he said.
The committee plans to review the rule curves in another 15 years, he said.
"We make these changes and sometimes the climate changes or, for instance, the cattails came along, something might change, so we want to evaluate it periodically," he said. "Fifteen years seems like it's a pretty good timeframe to have for evaluation. If you do it more often, you could have a few cold winters or dry years or floods that in a couple-year time, could really influence what your thinking is. But if you have 10 or 15 years, then things kind of even out a little bit so you can make a better estimate of the impacts of the regulation plan."
