Home News Local News State: Dam in good shape
State: Dam in good shape
Morgan Lake Dam is up to par with no signs of seepage, according to Oregon State Dam Inspector Keith Mills.
Mills told the La Grande City Council at a work session Monday night that both the main dam and saddle dam on Morgan Lake look fine after his inspection Monday.
“I just inspected it today and I didn’t find any seepage,” he said.
The saddle dam on the west side of the lake had to be repaired a couple years ago after it began seeping.
Mills also approved the city’s emergency action plan for the dam.
“As far as I’m concerned that’s ready to go,” Mills said, though some modifications do need to be made before the plan is adopted by the city council and county commissioners.
The plan lays out three scenarios for dam failure. Level 1 involves a slow, non-emergency unusual event. That type of situation calls for “inspection and monitoring,” according to a draft of the plan. A Level 2 situation is one that is rapidly developing and calls for emergency managers to prepare for worsening conditions and evacuations. Level 3 indicates that dam failure is “imminent or in progress,” according to the plan.
In the case of an imminent dam breach, City Manager Robert Strope said it would be nearly impossible to notify citizens and begin evacuations because it would only be a matter of minutes before water would reach the city. The roughly 2,200-acre foot lake would take only 11 minutes to come down Deal Canyon to reach La Grande. By that time, 6 to 7 feet of water could be expected on Alder Street. Within an hour and a half of a breach, 3 to 4 feet of water could be expected at Adams Avenue and 16th Street.
To avoid such a scenario, Mills recommended that the city look to put in a spillway to divert water into Deal Creek.
“If we have a spillway, we don’t have an overtopping failure,” he said.
Parks and Recreation Director Mark Touhey said there is an overflow pipe there now but it’s not adequate to cover overtopping.
La Grande-based civil engineering firm Anderson Perry and Associates has developed a design for such a spillway that has been preliminarily approved.
“I haven’t completely reviewed it, but it looks really good,” Mills said of the plan.
Mills also suggested some other protective measures for the city.
The first would be to grout piping underneath the dam. He also suggested putting in a monitoring device at the base of that dam that would notify public works or the police department of unusual changes in dam activity. Finally, he said a berm system would help to divert water to Sheep Creek rather than down Deal Canyon.
“It’s just an idea at this point,” Howard Perry said of the channel.
Councilor John Lackey asked if there was anything more the city should be doing for the dam.
“I’m really happy you’re doing what you’re doing,” Mills said. “This is as much as has been done in a long time. You’re making good progress.”