Two Grand River Conservation Authority dams need repair after April storm

Grand River Conservation Authority sign on June 4, 2022.

The Grand River Conservation Authority (GRCA) is working on repairs on two of their dams after an early April storm.

A messy mixture of snow, freezing rain and rain fell on parts of southern Ontario on April 2 and April 3.

In a release on Thursday, the GRCA said water levels in some of the local river systems were already elevated when the storm hit. The extremely high-water levels caused damage to the Wellesley Dam and Baden Dam.

The conservation authority said water overtopped the dams’ embankments or seeped through the embankments. The Wellesley Dam also lost operation of gate discharge equipment.

Emergency repairs were conducted and the dams were stabilized within hours.

The GRCA said neither dam was part of the conservation authority’s water control infrastructure.

Wellesley Dam

During the early morning hours of April 3, water levels at Wellesley Dam reached the overflow spillway and water began overtopping the east embankment, a portion of the dam that was not designed for overtopping.

The discharge gate equipment was damaged and the erosion was noted in the east embankment. The GRCA made the decision to leave the control gate in the open position until repairs to the gate and the embankment could be completed. The move resulted in the loss of the head pond, but Firella Creek will continue flowing through the drained area in a low flow channel.

An engineering assessment has been scheduled to identify any lingering safety and stability issues. The work will include a condition assessment of the concrete structure and a geotechnical review to address the seepage of the east embankment.

When the repair work is complete, the discharge gate will begin operating as normal again and the pond will be refilled. The GRCA believes the repairs will be completed by late spring 2025.

Baden Dam

Over at the Baden Dam, a hole in the embankment had been previously identified during routine monthly inspections. The conservation authority received an engineering report in the fall of 2024. The report detailed remedial measures to address seepage and improve overall dam safety and stability. A construction project had already been planned for 2025.

When GRCA staff inspected the dam on April 3, they noticed the seepage had increased significantly and temporary repairs were made.

The GRCA will move forward with remedial measures recommended in the engineering report. The design has been updated to include additional repairs needed after the April storm. Construction is expected to start in early May.