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Another dam mess on Lake Onamia - MessAge Media: Outdoor Recreation

Another dam mess on Lake Onamia

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Posted: Thursday, June 13, 2019 6:00 am

Last spring, water was so high on Lake Onamia that clumps of bog from the shoreline broke loose and meandered toward the rock dam at the lake’s only outlet — the start of the Rum River just west of the town of Onamia. 

Small portions of bog eventually worked their way over the dam and became stuck at the bottom of a railroad trestle (part of the Soo Line Trail) a few blocks down stream. 

Larger bogs lodged themselves a few hundred feet upstream of the dam causing the lake level to rise. 

The rise of Lake Onamia above the dam and the lowering of the levels below the dam had the potential of ripple effects up and down stream, including the possibility for a negative effect on the rice growth in this wildlife designated lake and blocking the access to the lake for duck hunters in the fall. The rise upstream also had the potential of affecting the water levels of Lake Onamia’s feeder lakes like Shakopee, Ogechie and even Mille Lacs, which could have had a negative impact on lakeshore property. 

The water’s rise was also a potential cause for concern for the sewers of the town of Onamia, and the blockage at the trestle was a potential danger for anyone tubing down stream and for the safety of the trestle itself, which supports a portion of the Soo Line Trail. 

What to do

With all those concerns, five separate entities, the Mille Lacs Band’s DNR, the State DNR, the State DOT, the city of Onamia and representatives from Mille Lacs County, met to come up with solutions for the potential problems. 

Heavy dredging equipment was brought to the dam site on July 18, 2018, and in one morning, much of the bog was pulled ashore and either piled near the highway or hauled away. 

The heavy equipment even made its way downstream to the trestle, where it worked its way into the stream bed and artfully unclogged the openings under the bridge. 

Most of that work became moot a few months later when more bogs broke loose and again caused a clog in the lake’s exit.

This time however, the water levels above and below the dam seemed to be stable and somewhat normal, causing officials monitoring this latest event to take a position of caution. 

“The Mille Lacs Band of Ojibwe and Minnesota DNR had a ‘cookie cutter’ (a boat mounted mulcher that rips apart bogs) scheduled to remove bog in the fall of 2018. But the machine broke down, and we were unable to use it then,” Tim Marion, DNR representative out of Cambridge, said. “Equipment like the cookie cutter can not be used on the ice in winter because of the uncertainty of ice conditions with the current of the river. So we planned to use the cutter in the upcoming spring or summer of 2019,” Marion said. Some results of the 2018 late summer bog situation were a less-than-normal rice harvest on Lake Onamia and hunters being inhibited from getting to their favorite spots on the lake in early fall.

The latest

That was then, this is now.

Who could have predicted another very wet spring, the results of which caused a Lake Onamia dam site situation even more severe than that of last year?

A local Onamia resident said he lived on Lake Onamia for over 50 years and only in the early 1970s when the Mille Lacs area got eight inches of rain in two days had he ever seen the lake this high.

How high? 

As of May 26, water levels on the lake inched their way near the edges of homes in Onamia proper and threatened overflowing roads near the lake. The bogs that were poised just upstream of the dam were backing up Lake Onamia water to a potentially dangerous level. 

Compacting the problem was the fact that every opening under the trail trestle was jammed with bog. 

These high water levels caused four of the five agencies who dealt with last summer’s bog problems to reconvene. Their plan was to, on the day after Memorial Day, employ a tracker hoe to collect bog above the dam before it could go downstream and catch in the railroad trestle. 

But Mother Nature somehow intervened. Water pressure had built up so high behind the huge bog that it forced the flotilla to break up on its own, and by early morning of May 27 (Memorial Day), what was a complete blockage the day before was now open water free-flowing over the dam. 

The only problem left to solve was the increased debris that had moved to the already stressed railroad trestle, forcing water to still back up upstream. 

The city of Onamia called in some emergency action on Memorial Day with a piece of excavation equipment that made its way into the Rum River under the trestle. With the Mille Lacs Band picking up the tab and the okay given by the local DNR, the equipment managed to free bog from just one opening before being forced to quickly evacuate the river bed. 

That one opening led to a minor lowering of the water upstream, and by Tuesday morning, officials were planning how to free the remainder of the trestle of the annoying bogs. The cookie cutter was brought to the shores of Lake Onamia on May 28, but the strength of the current near the trestle made it impossible to attack the bog.

Onamia city maintenance supervisor Gene Falconer said the city averted some potential major flooding problems when the bog broke up on its own and water on Lake Onamia was allowed to recede. 

“We had homes in town getting close to flooding, and we might have had some issues with our sewer system. But for now we are fairly back to normal,” Falconer said on the morning of May 28.

The local Band DNR and Minnesota DNR were at the trestle site on June 5, monitoring heavy equipment extracting bog from under the bridge. But even with the trestle bogs mostly gone, DNR officials, who toured the shores of Lake Onamia, are concerned that there is more bog material poised to break loose during another big rain event.

Photos by Bob Statz

 

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