Beginning in August 2011 and continuing into this summer, Gilmore Lake has been experiencing some fairly significant lake level changes. Although we had not been experiencing these types of rapid water level change in recent years, it was not uncommon in our lake’s earlier history. Some of us old timers can remember lake levels high enough to allow you to row a boat above the road at the Narrows Trail culvert. Did you know that in 1986 the Town of Minong contracted the Corp of Engineers to do a study on the feasibility of controlling Gilmore Lake flooding? A synopsis of the Corp’s findings is that a low head dam could be placed in the Gilmore Lake outlet to reduce back flooding into the lake from the Totogatic River.
So why did the flooding problem go away for about eight years? Well no one knows for sure, but the answer to that question is most likely the beaver dam that was in place on the lake outlet for the last few years, acting as a low head dam, and reducing the efforts of lake flooding from a rapidly rising river. The current frequency may also be influenced by water control procedures upstream at the Nelson Lake dam, saturated soil from multiple storms, and downstream downfall of trees from previous storms.
So what should we expect in the near future? More flooding opportunities. Any time we receive a couple of inches of rain in a short period of time, the lake will probably rise and usually peak 2-3 days later. Hopefully we will not experience a real deluge with 4 or more inches of rain because we may be floating boats in places we never expected.
Why is it important to consider possible solutions of water fluctuations? Well beyond the obvious–damage to boats and piers–the shoreline suffers damage each time we have rapid change in water level. Floating debris acts as a hazard to fast moving boats, tubers, and skiers. Perhaps most importantly, the river water entering our lake is higher in nutrients, causing greater growth of plants and algae. This is a little bit like adding “miraclegrow” to our Eurasian Watermilfoild (EWM). Also, as you have probably noticed, this year algae blooms have become more common and more intense.
What can be done to deal with the frequent flooding of our lake? One simple thing that will minimize damage along the shoreline is the reduce your boat wake when near the shore during high water. Tying down your pier section and removing your boats and gear from along the shore when you are away for extended periods of time will also help. A subcommittee to explore the feasibility of building a low head dam (vastly smaller than the one proposed by the Corp of Engineers) and coordinating river levels with Nelson Lake is planned. We need your help in this effort. Of particular use would be members that have either legal or engineer/construction experience. If you would like to help with this effort please contact Bill Huelseman. His contact information can be found here under the Board of Directors information.
In August 2013, a lake level gauge was installed on the southwest side of the culvert between Little Gilmore and Gilmore Lake. For reference, the lowest level recorded since it was installed was 5 inches. This should be considered our base level as the area was experiencing drought-like conditions and there was almost no water flowing out of the Lake into the Totagatic River.
If you have a PC and access to Google Maps, take a look at the upper are of Gilmore Lake using the terrain setting. It provides an excellent perspective on the low areas at the head of our lake that lead to our flooding problems. There is very little elevation change in this are which allows for the water to come into our lake during times of high river flows.
To learn more about flood events: Time line of flood events
Report from the Army Corp of Engineers: Corp of Eng Gilmore report
Water levels on the Totagatic: toto water level ref 2
River drainage information: Totogatic River Drainage