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VALLEY PARK, Mo. – Lone Elk Park‘s 17-acre man-made lake partially drained because of a sinkhole that opened up. This isn’t the first time this has happened in the lake’s 50-year history.

A man snapped photos of the hole forming Sunday night. Viewer Willie Nelson sent images of the hole forming to FOX 2. Bommarito Automotive Group SkyFOX helicopter flew over the area Monday morning and captured images of the leak in the lake. Water can still be seen rushing into the hole.

“From time to time we’ll have some sinkholes or swallow holes open up in this lake and it’s just natural cause of the topography where the lake was constructed,” said Tobi Moriarty, manager of design and development for St. Louis County Department of Parks and Recreation.

Park staff noticed the problem on Friday and estimate that the lake has drained about 6 feet in elevation.

“The lake does fluctuate but it was receding quite quickly,” Moriarty said.

Lone Elk Park is located near Interstate 44 and Valley Park. It is a popular place for people and photographers to visit because the elk roam free and visitors can see them up close.

The hole concerns St. Louis County Parks officials. It is the primary source of water for the park’s bison and elk.

There is some water still in the lake. It is not clear how the fish are doing after the lake lost so much water.

The depth of this sinkhole isn’t known yet but it’s in a similar location to the one that happened in May 2016. At that time, park staff noticed that the lake lost six to seven feet of water over 24 hours. They found a hole in the bottom of the lake.

“At this point, we’re assuming it will be similar. And that one took about 120 cubic yards of fill and was about 20 feet deep and 12 feet in diameter,” Moriarty said.

The repairs in 2016 cost approximately $25,000 in material.

A clay liner was placed over the limestone when the man-made lake was put in. A hole in the liner may be contributing to the leak.

Luckily, this won’t have an impact on the wildlife, it just doesn’t look as pretty.

“The aesthetics is the biggest part of this lake. People come here and expect to see a great, big, beautiful lake and we’ll try and get it back there for them as soon as possible,” Moriarty said.

St. Louis County Parks officials say that it is not unusual for a sinkhole to form in a man-made lake. Due to the geological makeup of this area, sinkholes are a continual problem. This part of the United States has a lot of limestone rock under the soil. When you build a lake on top of that material, it is not uncommon that a hole could form.

“It’s going to be an issue. So as long as we want to have a lake we’re going to have to do repairs,” Moriarty said. “we have these holes pop up along the whole perimeter of the lake.”

While we probably won’t ever know the exact cause, there are a few guesses, including the recent small earthquake in Eureka.

“We repaired a water’s edge hole over the winter and the water was just starting to get higher and higher so it could be the additional head pressure from the higher lake elevation but it very easily could have been that earthquake. That would make a lot of sense,” she said.

But as to whether or not this lake will be fixed?

“Yes, absolutely, and we have started the process to find a solution and repair the lake,” Moriarty said.