Have you spotted ice on the river?

Have you noticed whether there is ice forming on your local waterways?

It’s winter in the Ottawa River watershed, which means cold days are upon us. As temperatures continue to drop below freezing we will begin to see ice forming on the surface of lakes and streams within the watershed, as well as on some stretches of the Ottawa River. While many of us are familiar with all the fun winter activities that this ice will soon make possible, the onset and duration of ice formation can also provide us with valuable information about the health of the watershed.

Changes in ice thickness and the duration of ice coverage can be an indicator of the effects of climate change as the freeze-up and breakup of ice (aka. ice phenology) is largely dependent on air temperature. As global temperatures increase we will likely see shorter periods of ice coverage, with ice forming later in the fall/winter and breaking up earlier in the spring. In fact, such occurrences have already been observed. Following a study conducted by international scientists of 39 lakes and rivers located in northern Asia, Europe and North America, a trend of later freeze-ups and earlier spring breakups has been seen over the past 150 years (CCME). Surface observations for lakes in southern Quebec, Ontario, Manitoba and Saskatchewan have shown similar trends (NRCAN).            

River ice is important for a number of reasons including transportation via ice roads, ice fishing, snowmobiling and overall ecosystem health. Changes in the timing of ice freeze-up and breakup can have an effect on sediment and nutrient delivery. Changes in ice cover duration have also been known to influence spring flooding, particularly ice jam flooding, which can cause sudden increases in water levels resulting in severe flood damage.   


While much consideration has been given to sea ice formation under a climate change context, much less long term data exists for freshwater systems with observations of rivers being particularly sparse (NRCAN). The Ottawa River watershed is no exception: long term ice coverage data is limited for the waterbodies in our watershed and for the river itself. 

How to determine if the lake or river you are observing has ice on conditions? Ice on conditions correspond with the date when the ice is safe to stand on, generally when it is around 15 – 20 cm thick. The colour of the ice can also be a good indicator. Clear blue ice is generally safe, while white opaque ice tends to be less strong and black or grey ice indicates the presence of water underneath and thin ice. 

What stops ice on conditions from happening? While ice formation on lakes is relatively straightforward, ice formation on rivers if often more complex largely as a consequence of water flow and turbidity. As such, ice on conditions will likely not be observed in the white water regions of the river or in another other stretch known for fast flowing waters. 

How to determine if the lake or river you are observing has ice off conditions? Ice off conditions can be assumed on the date when it would be safe to navigate the waterbody by boat. For example, the official ice off date for Algonquin Park is recorded when a boat can safely navigate from the Lake Opeongo Access Point to the Happy Isle Portage in the North Arm of Lake Opeongo.

This is where you can help! Do you live near a lake or section of the river that is known to freeze over the winter? If so, you can help us create a record of changing ice conditions by letting us know when you first notice ice forming as well as when the ice breaks up in the spring. 

Please include the location, GPS coordinates as well as picture and weather conditions for that day if possible. You can submit your findings to Katy Alambo (kalambo@ottawariverkeeper.ca) or by using this form.  In addition, we will add your submissions to IceWatch, a national database of ice conditions. 

2 responses to “Have you spotted ice on the river?”

  1. Bob Simpson says:

    Town of Portage Du Fort on Ottawa River
    45.59 by 76.66 ice is completely across river as of Dec 20

  2. Mary Higgison says:

    Good ice covering most of the Ottawa river except where the strongest current flows on the Quebec side. Location is Cotnam’s Island, below the interprovincial bridge. Sorry no GPS. Ice formed December 18th, 2019.