Water Levels
Why the lake rises and falls—and how to monitor conditions in real time
Live Lake Level Monitor
Current lake level information is updated automatically throughout the year. Residents can use this data to track seasonal changes, monitor flooding events and compare current conditions with previous years.
Monitoring tracker to come -- check again soon
Why Do Water Levels Change?
Gilmore Lake levels rise and fall naturally as water moves through a large watershed and the Totogatic River-and then returns to normal.
1
Rain Falls Across the Large Watershed
Gilmore Lake sits at the downstream end of a 173-square-mile watershed stretching from the Hayward and Cable area west toward Minong.
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One inch of rain on one square mile is equal to about 17 million gallons, according to the U.S. Geological Survey
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Because the watershed is so large and relatively flat, heavy rain falling many miles away can eventually raise water levels on Gilmore Lake.
2
The Totogatic
River Bottlenecks
Flooding on Gilmore Lake is infrequent, and some years bring little or no flooding. It generally occurs only when substantial rainfall falls across a large portion of the watershed.
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During these major rain events, a narrow, sharply curving section of the Totogatic River north of the lake slows the flow of water. This quarter-mile “pinch point” can cause water to back up through the connecting stream and into Gilmore Lake.​
The red line marks the width of the floodplain at the north end of Gilmore Lake, where a stream flows into the Totogatic River.
3
Water Eventually Recedes
As water moves through the watershed and river flows return to normal, lake levels often fall rapidly. Dry weather can also lead to low water periods. The beaver dam at the north end helps slow water leaving the lake.
Lake levels change every year, but major flooding is uncommon.
The graph below shows how Gilmore water levels have varied over time in response to rainfall across the Totogatic watershed. Water levels naturally fluctuate throughout the year. Most years experience modest seasonal changes, while major rainfall events occasionally produce dramatic increases.
Gilmore Lake Levels 2014-2026
Extreme Water Levels Are Part of Gilmore's History
Gilmore Lake has experienced dramatic water level swings for decades. Historic floods occurred in 1946 and again in 2016, when exceptionally heavy rainfall across the Totogatic watershed caused the lake to rise approximately 11 feet in only a few days. While flooding can affect shoreline properties, these fluctuations are a natural result of Gilmore's unique connection to the surrounding watershed.