UTRCA Watershed Low Water Response - Current Bulletins/Media Releases

May 3, 2012

Record-breaking Dry Spring Continues

Upper Thames Watershed moves to Level 2 Low Water Condition

The ongoing dry conditions have prompted the Upper Thames River Low Water Response Team (LWRT) to move the Upper Thames River watershed to a Level 2 Low Water Condition.

A Level 2 Low Water Condition is part of a three-tiered advisory system used in Ontario to inform the public of local low water conditions. The LWRT had declared the least severe level, a Level 1, in early April.

Low water conditions are evaluated by looking at several indicators, including precipitation over the past three months, and stream flows over the past month.

“April’s precipitation totals were significantly below normal across the watershed,” explained Mark Shifflett, Senior Water Resources Engineer with the Upper Thames River Conservation Authority (UTRCA). “Our rain gauges measured only 25% to 35% of the rain that we would normally get in April.”

Environment Canada’s London Airport gauge recorded 25.6 mm of total precipitation in April, which is the lowest April total in over 60 years.

April was the watershed’s third straight month of below normal precipitation. As a result, flows in the Thames and its tributaries continue to fall. “Average stream flows fell to record low levels for the month at nearly all our stream gauges,” said Shifflett.

Specialists at the UTRCA say the ongoing dry conditions may have an impact on water quality and aquatic animals.

“Runoff from rain is one of the main ways that pollutants are carried into a stream,” explained Karen Maaskant, Water Quality Specialist. “With the dry conditions this spring there has been much less of this type of pollutant runoff to streams. However, without higher flows to flush the stream, any accumulated sediment and pollutants in the stream bed are not being pushed through the system as would normally occur.”

Aquatic Biologist John Schwindt picked up on this concern. “A lot of aquatic habitat will be covered with silt because we haven’t had spring runoff and high flows to scour away this silt. The result is limited and poorer habitat for the invertebrates that form the basis of the food chain, and impaired spawning habitat for many fish species.”

“Low water levels also impede the movement of many migratory fish species and may prevent them from getting to their preferred spawning habitat,” Schwindt said. “As most of our fish species spawn in the spring and early summer, continued low water will make much of the spawning habitat inaccessible or unusable and spawning fish more vulnerable to predators.”

If the drought continues, Maaskant expects to see more algae growth, especially in stagnant areas of the river. Algae growth reduces oxygen available for aquatic life.

To add to this concern, the UTRCA’s flow augmentation reservoirs at Wildwood (St. Marys) and Pittock (Woodstock) are below normal ranges for this time of year. Those two reservoirs have normally filled by this time with snow melt and spring rains. Those reservoirs are used in the summer months to augment flows in the North and South Thames River.

The dry conditions may also start to affect people with wells. “We have seen a general trend in our groundwater monitoring system of below normal water levels not only in shallower wells, but also in some deeper wells,” said Linda Nicks, UTRCA Hydrogeologist.

“People have asked me how much rain it will take to recover,” said Shifflett. “Right now, we’re at a rainfall deficit of 120 mm for the year. It will take some time to recover from that large a deficit.”

Find our more about current watershed flow and meteorological information and the LWRT.

Contact: , Senior Water Resources Engineer