Using Lake Sediments to Track Changes in Aquatic Plant Communities

Back in 2019, an MSc research project funded by the CLPOA, Western University, and MITACS was undertaken by David Zilkey on the changing condition of Gilmour Bay since the arrival in the area of European settlers.  Regrettably, Covid played havoc with getting this work completed in a timely fashion, but now a “Plain Language” advance summary of the aquatic plant portion of his report can be found here.  A more comprehensive report will be forthcoming.

A unique goal of David’s research was to see if paleolimnology techniques could be used to determine how nearshore aquatic plants have changed over time and in particular to see if there is a way to track the timing of the arrival and spread of invasive aquatic plants (eg Milfoil).  (The short answer is “maybe”, but will require future work.)

An intriguing aspect of the field work was the collection of an exceptionally long (6 m) sediment core using the lake ice as a platform.  This core would include material laid down since the time of the glacier retreat over 10,000 years ago.  Only the top 0.75 m were needed for this particular study; the remaining 5.25 m are being preserved at the LARS lab at Western for potential future research.

David’s project is one of three completed by Western University Scientists on our lake over the last few years.  We are very fortunate to have qualified scientists looking at the condition of our lake.  Not only does it help us better understand what is going on, it also establishes a knowledge base upon which future researchers might build.

The Warming of Canadian Lakes

It is an established fact that our lakes are getting warmer and the number of days of ice cover are getting shorter. And given all this crazy hot weather this year, climate change is a hot topic, even in the winter.

A recent article in the Globe and Mail

begins with:

“Canadian lakes are in hot water over climate change, a new research survey has concluded.

“Canadian lakes are warming twice as fast as the rest of the lakes globally,” said York University biologist Sapna Sharma, a co-author of a paper published in the journal Bioscience.

Sharma and her colleagues pored over 143 studies from around the world to try to summarize how climate change is affecting the globe’s 100 million lakes.

Lakes that have been ice-covered at least part of the year are experiencing the biggest changes, they found.

Warming air temperatures have reduced ice cover an average of 31 days over the past 165 years, with ice cover disappearing six times faster in the past 25 years. About 15,000 Northern Hemisphere lakes that once froze every winter are now experiencing ice-free years and 6,000 of those lakes may never freeze again.

Water temperatures are rising as they absorb more sunlight, with the upper layers of lakes warming up even more quickly.

Lakes around the world are already warming by a third of a degree Celsius per decade, with ice-covered lakes warming twice as fast as the global average. By the end of the century, average global lake temperatures are expected to rise anywhere from one degree, to 4.

That increases water loss from evaporation and encourages blooms of toxic algae.

“In Canada, as well as other places in the world, we’re seeing increased incidence of these algal blooms much later in the season,” Ms. Sharma said.

Lake Superior, the world’s largest lake by surface area, now experiences algae blooms. In 2014, a secluded lake in Ontario’s Algonquin Park was closed to camping because of algal blooms – the first such bloom in more than a century.

To read the academic article related to the above news clip, see

The 2022 CLPOA yearbook p. 54 has an article on the decreasing ice cover at Chandos Lake, Over the last 35 years or so, on a trend line basis, the ice cover on Chandos has decreased by about 11 days. A pre-print of this article can be found here

When is the ice REALLY out?

2022 was an unusual year for Ice Breakup.  Just as the ice was about to leave, there were a couple of days of high winds which seemed to concentrate the remaining vestiges of ice into ice packs, which were then driven into various bays.   In South Bay, for instance the ice usually recedes from the shore, but this year the aforementioned icepack came back to the shore and there it lingers.

The waters immediately before the culverts are usually open all year, due to the flow of fast shallow water.  This year, however, an icepack was pushed towards the culvert and lingered.  In fact, on the 18th of April there were people launching docks there in the open water just south of the pack!

So, when is the ice really out?

One could decide that it is “When not enough ice can be found to adequately water my scotch”.

Another criterion could be “When the ice cover breaks up and open water becomes extensive.”

If one is looking for trends, i.e., how things change over time, the key is to be consistent in the observation and evaluation process.  So, each of the above are equally valid criteria for identifying trends in “Ice-Out”, so long as they are applied as consistently as possible year over year.

The United States Environmental Protection Agency (EPA) monitors Climate Change Indicators, and one of them is Lake Ice.  Their take on the subject can be found at

Quoting from their website:….

Thaw dates occur when the ice cover breaks up and open water becomes extensive.

– Data used in this indicator are all based on visual observations.  While the procedures for making observations of lake ice are consistent over time, visual observations by individuals are open to some interpretation and can differ from one individual to the next.  In addition, historical observations for lakes have typically been made from a particular spot on the shore, which might not be representative of lakes as a whole or comparable to satellite-based observations.  Considerations for defining the thaw date are specific to each lake.

– Thaw dates for most lakes show a trend toward earlier ice breakup in the spring.  Spring thaw dates have grown earlier by up to 24 days in the past 114 years.  Nearly all lakes were found to be thawing earlier in the year.

This year, using the same procedure employed by the same observer for the last 35 years, the Ice-Out date at Chandos has been determined to be April 15, and although this may be understandably unsatisfactory to some, for reasons explained above, it is what we are entering into our historical record.  (Now please get me a scotch, on the rocks!)

Spring Report 2022

Spring Flood
The likelihood of a spring flood this year seems remote. Much of the snowpack in the watershed has reduced greatly, so unless there is a large quantity of rain, we are home-free in that regard.

Web site additions – TARP
There have been a couple of additions to the website, notably to do with Dr. Paul Frost’s work on Water Quality in the Kawartha Highlands, which has included Chandos Lake.

The first is the TARP 2022 Report. which can also can be found under this subtab along with other TARP reports.

The second is a useful chart on comparative Lake sizes in the area. It can be found under this tab.

Cottage Investors and Rentals on the increase in Ontario
Recently there has been a lot of concern throughout the province regarding the increase in rental properties in lake front communities. Apart from changing the nature of these various towns, it is also driving up property values and increasing the load on the lakes, which is a lake health concern. Many communities have started to regulate and limit the number of rental properties.

As an example, see
This is something that we hope Peterborough County and North Kawartha Township are trying to get ahead of before it becomes a problem here. The County Official Plan is presently undergoing a review .

Top of the Season!

Dear faithful followers all,

Thank you for your interest in this site. It helps to keep the motivation up 🙂

I hope you are all healthy and that you have folk you love, to share the joy of the season with. For myself, it has been a disrupted season. We have lots of family, and Covid has been doing its best to assert itself in quite an unhelpful way. However, we have much to be grateful for, and this certainly is the time to acknowledge and celebrate our families and our good fortune.

2021 has been an a relative quiet year concerning the lake, at least science-wise. Certainly covid has curtailed many of the usual activities we all enjoy.

The water levels are as high as I have ever seen them for December, and today they are at 1026′ 10″ as measured at the South Bay stick gauge. The summer levels stayed fairly high as well, compared to previous years.

In 2020/21 we posted an Ice-In date of January 10, 2021 based on Cathy Burgess’s observations. I think this year, once she has made a determination, we will ask around the lake (via the facebook page) just to see that everyone else sees ice as well. Of course, right around the culverts, there likely won’t be any, because of the outlet flow, so we’ll have to ignore that.

Early in 2022, we expect to get a report from David Zilkey, a graduate student working for Prof Katrina Moser of Western, on the effect of invasive species (eg Milfoil) upon nutrient delivery to Gilmour Bay. (This report has been delayed due to the constraints being placed upon the researchers by covid)

Well, I hope that 2022 is a kinder year for humanity, and that you in particular experience much joy, health, and peace.

Hummingbird Departures 1986-2021

Cathy Burgess has been recording the arrival and departure dates for red throated hummingbirds since 1986. The departure date for 2021 was observed to be September 18.

Here is a graph of her data. On a trend line basis the hummers are leaving a week later than they were 35 years ago. A bit more commentary can be found under the Climate Change Signals tab

Website mobile device issues

Dear followers all,

it recently came to my attention that although laptop versions of this website generally worked ok, the mobile versions, such as for an iphone or ipad, did not show many of the charts and pictures.

This, hopefully, has now been remedied.

Please, if you note any malfunctions, it would be highly appreciated if you would let me know.



2020 Lake Partner Program Phosphorus Report for the Kawarthas

The Kawartha Stewards Association (KLSA) recently published this report on phos in their set of lakes. (Chandos is not included).

These lakes are flow-through, meaning that one flows into another, and so phosphorus levels in one lake can affect levels in the downstream lake. It also means that the levels can vary widely.

On a comparative basis, phosphorus levels in Chandos are in the 10 µg/L range,, whereas the Kawartha lakes reported vary widely from 5 to 25.

Secchi Depths at Chandos are in the 5-6m range, whereas in the Kawartha Lakes they range from 2 to to 7.

For more information regarding Chandos, please see the Trophic Status tab, or the Phosphorus tab.

Gilmour Bay Namesake

Gilmour Bay was most likely named after the Gilmour Bay Lumber Baron family from Trenton.

If you have 66 minutes or so, it is very informative to watch the Youtube video “Lumber Baron- The Gilmour Years” at

The last 5 minutes or so has a really hilarious sketch called “the sawmill” -very chaplinesque.

We are most interested in finding out more about the Gilmour Bay lumbering operations.

Chandos lake appears in the map below, but is unnamed. Of course, before 1935 it was called “Loon Lake”.