Crews still are investigating a possible problem with a drain in the city reservoir after they found initial signs of a problem this winter.

The Durango City Council set aside $300,000 for repairs in March after clay was discovered in the water draining from the dam.

Clay could be a symptom of erosion within the dam or it could be a problem with a manhole and pipe that never was grouted properly, said Utilities Director Steve Salka.

All earthen dams are designed to leak but not erode.

So far, the city has spent about $20,000 on the exploratory work.

“We’re trying to stay ahead of a potential problem,” Salka said.

One of the first steps was to lower the water levels in the lake for safety reasons, and since that was done, crews have not found any clay in the drain.

A contractor is drilling wells below the dam to monitor the ground water. These wells could indicate a problem when and if the reservoir is filled for the summer.

If the level of water in the reservoir must remain low, it should not impact city residents’ usage, Salka said.

If the problem is confined to grouting in the pipe, the fix could be relatively inexpensive and repaired quickly.

But a larger problem could require the city to dig a trench below the dam this fall to access the drain.

Salka previously had hoped to identify the problem before summer, but rain and no written record of previous dam repairs in the early years have slowed the project.

“We have to do this right,” Salka said.

mshinn@durangoherald.com