I have archived the February 2025 water level chart (above, and at left). The dry conditions in January continued into February with us receiving only 1.82 inches of water, well over 3/4 of an inch less than the average 2.61 inches we normally see in February. Of all the months, February is the one with the least amount of precipitation and we couldn’t even meet that low bar. Most of the precipitation was in the form of snow and as a result, we ended the month with a good snow pack. The prospects for spring runoff and a lake-flushing are good.

At the beginning of the month, the lake was already down over 18 inches which is more or less our target winter water level. When it appeared early on that February was going to be a dry one, we decided to install some stop logs  (3 to be exact) to keep the lake level from dropping further. It worked. Other than minor leaks, this effectively stopped all outflows. So what happened to the lake level?

Very little of that February precipitation actually ended up as water entering the lake directly, it was mostly snow but the lake level still managed to rise 2.4 inches from where it started at the beginning of the month. While some ground water undoubtedly seeped into the lake during this time, most surface water and streams were frozen. So where’d all the water come from to raise the lake level 2.4 inches? Good question! Most of the lake level rise was the result of the weight of snow on the ice on the lake. Even though this snow is on top of the ice, the added weight weighs down the ice, causing it to displace more water. Archimedes is the guy that figured out this principle of displacement supposedly while taking a bath: when an object is partially or fully submerged in a fluid, it experiences an upward buoyant force equal to the weight of the fluid displaced by the object. In other words, the force pushing an object up is equal to the weight of the fluid it displaces. While this isn’t entirely intuitive, think of a glass of water with ice cubes floating in it. You know that adding more ice to the glass will cause the level of water in the glass to rise right? This same principal applies to Clary Lake: add snow on top of the ice, and the lake level will rise.

Now that we understand the principle of displacement as it applies to the lake level, we should be able to figure out what will happen when the ice and snow melts. One would think that the ice will melt and add water to the lake resulting in the lake level rising, but this is not what happens. The lake level is already higher as a result of the displacement caused by the ice and snow and when it melts, the lake level isn’t going to change, neither rising or falling. Confused? Refer back to that glass of water with ice cubes in it only this time, fill the glass to the brim and wait for the ice to melt. The water level in the glass will not change because the melted ice has the same volume as the water it displaced. Here’s a great illustrated article that explains what’s going on.

Low Flows

The lack of precipitation this winter has resulted in significantly reduced outflows from Clary Lake. The chart at left shows outflows in acre-feet (an acre-foot of water is 1 acre of water 1 foot deep, or 43,560 cubic feet of water) and lake volumes flowing out of Clary Lake on this date for the past 7 years. The previous lowest flow year  was 2021 when 0.26  lake volumes had flows out of the lake by this date. So far this winter only 0.20 lake volumes have passed downstream. Three times more water went down stream on this date in 2023 and 2.7 times more last year. That’s a big difference! Obviously when spring melting starts, this situation is going to change rapidly but for now it means our lake water is looking pretty stagnant, much as it would late in the summer when the lake level and outflows are typically low. Lake productivity slows down in the winter due to cold water temperatures and lack sunlight due to ice cover, but it doesn’t stop. I think a good spring flushing will be very important for water quality this summer, assuming the runoff doesn’t bring in a lot of sediment with it. Time will tell.