FAYETTEVILLE -- The sycamore trees lining the Lake Fayetteville dam could cause a rupture that would flood Johnson and anything in between, which is why the trees are getting cut down this summer.
The Arkansas Natural Resources Commission classifies the dam as high hazard, meaning failure would result in injury or death to people living downstream and cause significant property damage. City crews will remove the 19 trees once conditions are dry enough.
The roots have caused seepage, and any fallen trees would take a chunk of the dam with them, said Tim Nyander, utilities director for the city. Nyander's department oversees the Lake Fayetteville dam and the dams at Lake Wilson and Lake Sequoyah.
"We've done a tabletop of what would happen if the dam failed with Emergency Management," he said. "We would have to evacuate Johnson as fast as we could. Anything downstream is going to be water and probably make its way all the way to the interstate."
During high water levels, such as when floods hit Northwest Arkansas in April, the trees' root balls become submerged. Root balls refer to the mass formed by the roots of a plant and the soil surrounding them. Nyander said his department can handle cutting the trees down but might need to hire a contractor to remove the root balls.
Otherwise, heavy wind coupled with extensive rain could topple the trees, creating a tunneling effect and causing an immediate failure of the dam. The trees likely will go to the chipper and become mulch, Nyander said.
The Arkansas Natural Resources Commission has granted permits for about 400 dams in the state and classifies them as low, significant or high hazard. High-hazard dams get annual inspections and the owners of those dams, in this case the city, have to have emergency action plans in place and carry out emergency drills and exercises in order to be able to protect anyone downstream from harm, said Edward Swaim, water management division chief.
"As a permit condition, we send staff inspectors out to look at permitted dams and recommend maintenance," he said. "Typically this would involve removing woody vegetation, repairing animal burrows, patching concrete structures, etc. High hazard dams are usually inspected annually. Dam owners make more frequent inspections as part of their ongoing maintenance."
An inspection on April 4 found the upstream slope of the dam and the crest appeared to be in good condition. However, inspectors noted the large trees growing on the slope with their root systems causing small depressions and cracks in the walking track at the crest, according to an Arkansas Natural Resources Commission report.
Torrential rainfall caused flash flooding throughout the region in late April. Nyander and his team inspected the dam afterward and decided the trees had to go.
"We noticed that flood event was the highest anybody that's here has seen it get," he said. "Some of those trees, the bottoms of them were under water. That's a little bit of a concern."
Inspection reports dating to 2012 found few, if any, other issues with the dam.
Brothers Steven and Peter Du on Thursday took a walk down the Lake Fayetteville Trail and pointed out how the trees create a pleasant corridor. Steven Du wondered if some of the trees could be spared.
"I think that it's unfortunate if they cause a safety issue," he said. "If it's avoidable, cutting them down should be avoided. But if there's no way to stop it, I think safety does have to come first."
Peter Du suggested planting trees on the other side of the slope. The city's urban foresters, Lee Porter and John Scott, considered the idea but scratched it because it would likely have the same result.
Porter and Scott aren't sure how old the trees are but know they grew along the slope of the dam on their own. The root systems already have caused some erosion.
"We are quite sad they're going to be removed, but we totally understand it because it is a safety issue and a structural integrity issue of the dam," Scott said.
The urban foresters have a tree planting scheduled for the fall and will look at the possibility of planting trees around Lake Fayetteville, Porter said.
"We know that fishermen love to fish under them," she said. "I think everybody that uses the Lake Fayetteville trail system likes to use those trees for shade. I wish they didn't have to go."
Members of the city's Water, Sewer and Solid Waste Committee, which consists of half the City Council, discussed the tree removal during a regular meeting Tuesday.
"It's going to make a visual impact," said Alderman Mark Kinion, who serves as chairman of the committee. "I think we can expect that people are going to wonder what the heck we're up to."
Alderwoman Sarah Marsh suggested putting signs up to let passers-by know what's going on. Alderwoman Sarah Bunch expressed sadness over the loss of shade along the trail.
Alderman John La Tour suggested planting wildflowers in place of the trees to have something there. Kinion concurred.
"It's going to leave a very open area," Kinion said.
NW News on 06/18/2017