CARIBOO OUTDOORS: A further look at lakes in consideration of climate change

Published 5:00 pm Saturday, January 31, 2026

In my last column, I spoke about how climate change could impact our lakes by changing the way they respond to warmer temperatures and continued evaporation. Lakes are dynamic, containing a myriad of living organisms in the form of plant and animal life. Any change, no matter how subtle, could impact these life forms.

I will now step back a bit and explain that lakes are classified as either eutrophic, containing nutrients suspended in the water that are readily available to all life forms, but mainly the plants, and oligotrophic, meaning there are not a lot of nutrients suspended in the water, and what nutrients that are there to support plant life are carried in by feeder streams. I would say that Simon and Irish are two classic examples of eutrophic lakes, while a lake like Canim or Quesnel would be more in the oligotrophic spectrum.

I have always jokingly said that in a eutrophic lake, it is a fish eat insect scenario, while in an oligotrophic lake, it is a fish eat fish scenario. The balance of our local lakes could be classified as somewhere in between, or mesotrophic, having moderate levels of nutrients and biological productivity. Eutrophic lakes can be identified as shallow, weedy, and often a bit brackish in colour. Because of their limited depth and plentiful weeds, they are subject to winter kill as plants decompose under the ice.

They are also some of our most productive fisheries, and the most vulnerable to warmer seasonal temperatures and decreasing water levels. Without checking, my guess would be that they are close to or slightly above neutral Ph. Of course, as I mentioned in my previous column, Green Lake, which has a high Ph making it susceptible to fish mortality as the lake evaporates, may be the exception.

From what I have read, most of the mid-sized and larger lakes in our region should be able to sustain a quality fishery for some time to come. Of notable concern, however, is Big Lake, west of 100 Mile House. Declining water levels in this body of water have made it not only prone to winter kill, but also as the lower water level recently experienced has created a higher Ph, which has a real potential to impact the fishery there.

Since I have only visited a scant few of the lakes in our area, I will leave it up to the reader to think about the lakes they have been to and think about a classification that may be applicable.

As I mentioned earlier, I think most of our lakes probably lie in the mid-range between eutrophic and mesotrophic. Bear in mind, I am no expert at lake classification, but can only look at the definitions and ascribe a layman’s estimation.

I was able to locate information on a few of our local lakes by accessing the following websites: the BC Lake Monitoring Portal, Ecological Catalogue (Eco Cat BC) and the Fish Inventory Data Query. The most recent information I could find, doing a quick check in Eco Ca,t was a summary prepared by Russell Bowbroski, Fisheries Stock Assessment Specialist in the Cariboo Region, completed in 2015. In this report, Sheridan Lake is listed as having a Ph of 8.9 and Howard with

a Ph of 8.2. The BC Lake Monitoring Portal data from 1998 shows Horse Lake with a Ph of 8.39; Fawn Lake 6.1 to 8.8 Ph (it lists both in different places, so I showed them both); Bridge Lake 7.6 to 8.25 (same explanation as Fawn Lake); and Deka as 7.4 to 8.2.

I think it would be kind of interesting to take Ph measurements on different lakes that I fish.

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