Recently Mike Anderson put in the On-the-Water report that Pyramid Lake began to “turn-over” or “flip”. I thought it would be a good opportunity to review what happens to a lake when it turns over and how it is a good thing for the lake and specifically how it is a good thing for fly fishing Pyramid Lake.

Here is Mike’s most recent on-the-water report that we are referencing

In this video and in general discussions around the shop we will often refer to a lake “turning over” or “flipping”. This is a natural occurrence as we progress into the Fall season and temperatures begin to drop surface water temps will also cool.

A lake will stratify (different layers) into different temperature zone vertically over the course of a season (summer, fall, winter, spring). During the Fall and Winter the surface layer temps can be cooler than the layers below. When the surface temps are cooler than the water below the denser water will literally sink through the water column. This process can be hastened by wind pushing cooler water to one side of the lake allowing the water below to access.

The mixing period or the time that the lake is actively “turning over” can be visually distracting but is actually very good for the biological health of a stillwater. The combination of warmer water, bottom sediment and access to sunlight can create algal bloom near the surface. The bloom is natural and can be beneficial by increasing available nutrients for other biological processes.

A while back we had the chance to put out a podcast episode with Dr. Sudeep Chandra from the University of Nevada’s Global Water Center. In it, Dr. Chandra explains very well this process and the benefits that can be observed.

Following the flipping of stratified layers and seasonal mixing. The water will clear and we have experienced the best fly fishing of the season at Pyramid Lake. The LCT will access the shallower environment and begin actively feeding on midge and other aquatic insects that have been stimulated by algae during the flip.

When you see the “green soup” at Pyramid Lake and other stillwaters. Don’t give up hope. Biological processes are happening and the fly fishing should get better really soon.