Dry conditions across Rideau Valley due to early spring, limited rain

3 min read April 20, 2021

Although nobody can predict the weather, and despite some recent rain, 2021 is shaping up to be an abnormally dry year across the Rideau Valley watershed if the current trend continues.

Rideau Valley residents enjoyed a relatively easy winter with warmer-than-normal temperatures in every month except for February.

Combined with below-average precipitation and above-average temperatures in March, all evidence points to a dry year ahead.

Weather and water level conditions have been pointing in this direction since winter began in December 2020:

· Approximately 50 mm of rain fell across the watershed between December 24 and 25, resulting in short-term elevated water level and flow conditions in many lakes and rivers. Levels and flows receded by the end of January, with most regions dropping to below normal for much of February and March.

· Snowfall was also limited. There were only two large snowstorms of about 20 cm each (one each in mid-January and mid-February) and several smaller snowstorms of about 5 cm each. Based on recorded snow fall amounts and RVCA snow monitoring results, the total amount of ‘snow water equivalent’ this winter was about 80% of normal. (To learn more about how we calculate the snow water equivalent, check out this video: www.youtube.com/watch?v=S30J86FfnZg)

· Monthly temperatures from November 2020 through January 2021 were, on average, 1 to 3 degrees Celsius above normal, with slightly cooler than normal temperatures in February. The overall warmer winter concluded with very mild temperatures in March.

· Daytime temperatures rose well above zero from March 9 through 12, resulted in rapid snowmelt across the watershed and subsequent short-term elevated water levels/flows in most waterbodies. This was followed by a large rain event of 40+ mm in late March which caused water levels/flows to increase again, but they quickly declined with the limited rainfall into mid-April.

So, what does this all mean? All water levels and flows across the Rideau Valley watershed are currently well below normal for this time of year. Current flows on the Rideau, Jock and Tay Rivers and Kemptville Creek are all between 30 to 40% of the typical seasonal averages. (For current and historical water level and flow information, see www.rvca.ca/watershed-conditions. To learn more about low water conditions, check out this video: www.youtube.com/watch?v=-MIfvEDoDfs&t=21s)

Flows on the Rideau River are routinely augmented by several reservoir lakes located in the upper watershed, west of Westport. These lakes store water in the spring and sustain flows throughout the drier summer months. Water levels and flows in the primary reservoirs (Bobs Lake and Wolfe Lake) are currently below normal for this time of year. Flow through lakes such as Christie Lake have also been affected and are trending well below normal.

Parks Canada staff are carefully managing the outflows in the reservoir lakes and have indicated that if we receive normal precipitation amounts over the next couple of months, lake levels are expected to gradually rise to seasonal averages.

Parks Canada staff also manage water levels and flows in the main body of the Rideau River from Big Rideau Lake through downtown Ottawa, including the Rideau Canal lock system.

Parks Canada staff have indicated that navigation levels along this reach will be achieved by the long weekend in May. For more information from Parks Canada, see www.pc.gc.ca/en/lhn-nhs/on/rideau.

RVCA staff are currently preparing to meet with the Rideau Valley Water Response Team, which is made up of municipal and agency partners. The primary purpose of Water Response Team is to provide a forum for the sharing of information among water managers and water takers, and to facilitate co-operative decision-making on the conservation of limited water supplies at the early stages of and throughout drought events, as they occur.