Low Water Conditions ended in Upper Thames River watershed (low water update, November 4, 2022)

The Level 1 Low Water Condition that has been in effect for the Upper Thames River watershed since July 15, 2022, has been terminated. The Upper Thames River Conservation Authority (UTRCA) recommended the change to the local Low Water Response Team based on precipitation and streamflow indicators as of late October.

30 Day Precipitation

The Upper Thames River watershed received an average of 91 mm of precipitation between September 20 and October 20 (about 108% of normal). The long term average for this period is 84 mm, measured at the London Airport and reported by Environment and Climate Change Canada (ECCC).

90 Day Precipitation

The watershed received an average of 224 mm of precipitation between July 22 and October 20 (about 90% of normal). The long term average total for this period is 248 mm, measured at the London Airport and reported by ECCC.

18 Month Precipitation

The 18 month (April 01, 2021 – October 01, 2022) precipitation measured by ECCC at the London Airport totaled 1426 mm, or about 98% of normal. The 18 month long term average precipitation total for August is 1456 mm.

A Level 1 Low Water Condition is triggered if the three month (90 day) total precipitation falls below 80% of the long term average value.

Monthly Streamflow

For most indicator stations in the Upper Thames River basin, the October 20th 30 day average stream flows were generally between the 25th and 50th percentile flow rates, indicating little concern regarding low water in most locations. The Middle Thames River and the North Thames River below Mitchell were both below the 25th percentile flow for this time of year.

Reservoir Status

The UTRCA maintains three large reservoirs and several smaller ones across the watershed. Two of the large reservoirs provide flow augmentation in the summer, meaning they store spring runoff and then slowly release this water back into the river system in the dry summer months and into the fall. Both Pittock (South Thames River in Woodstock) and Wildwood (Trout Creek above St. Marys) reservoirs are continuing to augment downstream flow, with winter levels expected to be reached in November.

For more information:

Contact: Eleanor Heagy, Coordinator, Communications and Marketing