SPOKANE, Wash. — The leaking Mill Creek Storage Dam near Walla Walla poses an “unacceptable” risk to the public and will be specially managed until it can be repaired, the U.S. Army Corps of Engineers said this week.

The 67-year-old dam is seeping water and is especially dangerous when Bennington Lake is more than 17 percent full, the agency said. It is typically kept just 5 to 10 percent full.

Mark Lindgren, engineering chief with the corps in Walla Walla, said the dam can still be used to prevent floods in the Walla Walla area but will be more closely monitored to make sure it does not collapse.

“We basically made the decision for this flood season to use the dam, and this one-time exposure should have a relatively low risk,” Lindgren said.

The corps is in the process of evaluating all 610 of its dams nationwide for safety. Dams get a rating of 1 to 5, with 5 being safest and 1 being the most at risk.

The Mill Creek Dam is the only one in the Walla Walla District — which covers portions of Washington, Idaho, Oregon, Wyoming, Nevada and Utah — to be rated a 1.