Murfreesboro Diamond

Narrows Dam performs exactly as expected during flooding April 16, 2008 - No reporter cited

By Heather Grabin
Editor

Flash floods poured over southwest Arkansas last week, and many eyes began to watch the level of the water around them.

Creeks began to rise and ponds began to overflow. The swimming areas at Lake Greeson grew much larger as water flowed over campsites, roads and parking lots.

The water level of the Little Missouri was maintained for minimum property damage by the U.S. Army Corps of Engineers at Narrows Dam, just as it was designed to do.

The dam was created for flood control and hydroelectric power by the Flood Control Act of 1941. Construction began on the dam in April 1947 and the dam was dedicated in July 1951.

1968 is the only year that Narrows Dam has had water go over the spillway, but last week the water kept creeping closer and closer to the top.

According to Ned Hollenbach, U.S. Army Corps of Engineers, the dam opened the flood gates for a time the afternoon of April 8 and then the dam ceased generating alltogether. 

According to Hollenbach, much of the water that was flooding the Little Missouri River bottoms was coming from Muddy Fork, which is not controlled by the dam. Narrows Dam is almost always under a power restriction whenever there is high water in the river bottoms.

According to Hollenbach, the water level of Lake Greeson was three-feet and nine-inches below the spillway at 11:30 a.m. Friday, rising ½ inch every two hours. The dam began to release water at noon on Friday and continued in intervals throughout the weekend.

“During this latest flood event, Narrows Dam and Lake Greeson have perfomed exactly as designed. The dam was able to contain flood waters coming down the Little Missouri River, and the lake was able to store those waters preventing further flooding downstream. Now that the waters downstream are receding, we can release the stored flood waters at a controlled rate so as not to cause additional downstream flooding. The dam did this without exhibiting any undue stress or increase in seepage. All of our employees are trained in dam safety and are knowledgeable in the operation of Narrows Dam. Flood damage reduction and hydropower are the two authorized projects of the dam and we take our job seriously,” Hollenbach said Friday morning.

Hollenbach continued, “Since early in the morning on April 4, we have performed around the clock inspections. There are approximately 220 steps on each side of the dam that are walked every two hours during our inspections, so this work can be physically exhausting. The 24-hours-per-day inspections also require a large amount of overtime work, which is costly, and comes directly from project funding which is already stretched thin. However, there is no cost that can be put on the safety and well being of the many citizens, and their property, living downstream of Narrows Dam.”

According to Hollenbach, if the water level of the lake were to reach the top of the spillway, it would come over very slowly at first. Wind driven waves would go over before the actual level of the lake reached the spillway.

According to Hollenbach, Narrows Dam is made out of concrete that has a very long life span. Even during periods of normal water level an aggressive monitoring system is used, but since April 4 the dam has been monitored every two hours and has shown no sign of any significant changes in seepage, wet spots or pressure.

“The integrity of the structure is considered to be extremely sound. Although, we hope no one would ever need to evacuate, during a flood event you should obviously head for high ground, but preferably not across the Little Missouri River bottoms. I would plan my route towards Narrows Dam, Kirby or Delight. There are plans in the future to hold a tabletop exercise where we would meet with local emergency operation personnel, local government, local law enforcement agencies, rescue units, EMT’s and local hospitals and put a plan into place should there ever be a dam failure. We do have a Flood Emergency Plan already in place. The key to making the plan work is good communication. A lot of people would have to be notified in a short period of time,” said Hollenbach.
Murfreesboro’s Mayor Jim O’Neal said that he has already been thinking of ways to plan an evacuation route for the citizens of the town and that he has already been discussing the bids for a new weather warning service with Steve Conly, of the Office of Emergency Management. O’Neal said he would be speaking with Conly about an evacuation route and plan in the near future.

↑ Top