RVCA Drought Update

A message from RVCA's Senior Water Resources Technician, Patrick Larson:


I have meant to put together a summary of conditions in the watershed for awhile but have held off because I wanted to be able to report on a meeting the Conservation Authorities in Severe drought had asked for with Ministry of Natural Resources and Forestry. Unfortunately, it has taken longer than anticipated to come together and is now scheduled for the November 14th. So, a summary now and a report on the meeting after the 14th.

An average of 15.4 millimeters of rain fell in the first two weeks of October. An average of 75.4 mm fell in the next six days, most of that on the 20th through the 22nd. The good points about this rain event were that it was well distributed over the watershed and wasn’t intense rain that could have overwhelmed urban drainage systems. However, while there has been some rain since, it has not been enough to sustain flows so most streams have again declined. There needs to be enough regular rainfall to fill the wetlands and saturate the soil before streams can reach and stay close to historical averages. Now, as streamflows decline, the pattern of disconnected pools is occurring again. A concern is that what aquatic populations are left, after struggling to survive in the warm water, low oxygen and shrinking pools through the summer, are now faced with shallow pools that are going to freeze possibly solid.

Lakes in the watershed have also had increased levels from the rain with the reservoir lakes rising closer to targets. Bobs Lake is actually above target after a summer that was a trial for boaters as the water got lower and lower. The other three reservoir lakes are all below the respective targets. To put a bit of a positive spin on what has passed, there was water throughout the summer in all watershed lakes, just not what residents have been used to. Some farmers have had quite good crops from soybeans to apples. We have had only limited contact with people who have had their wells go dry and do not know what the present status is.

To close, with flows falling again, there is really no change in the rationale for the Severe Drought status that flows and levels have not been restored to normal. The one outlier is Kemptville Creek that received over 100 mm of rain and had levels at the Oxford Mills Dam rise a metre to summer target levels, just in time for the adjustment to winter levels. Flows have not declined as much as the rest of the watershed so, technically, that sub-watershed could have the drought status raised but it might be prudent to leave it and the rest of the Rideau watershed in Severe status so as to avoid confusion if conditions decline further.

Contact: 613-692-3571 or 1-800-267-3504 ext. 1210

Lyse PrendergastComment