Dallas Geologist Warns of Fault Lines Under Lewisville Lake Dam, Wants to Know If Corps Is Listening

An effort by the Bureau of Land Management to lease mineral rights on 259 acres of BLM land near or under Lewisville Lake is off the table for now, thanks partly to protests from lakeside towns worried about what drilling for oil and gas might do to the reservoir's dam.  

The bureau pulled the parcels off the block in April, but that doesn't mean they might not be up for lease again in the future. Before that happens, Dallas-based geologist Gerald “Jerry” Bartz would like to hear from the bureau or the Army Corps of Engineers about his findings. Seismic activity triggered by drilling activity could lead to the dam's failure, says Bartz, who is critical of the Corps for its lack of transparency concerning the risks of human-induced earthquakes on Texas reservoirs.

“This is an important issue,” Bartz says. “We can’t have education silo where the Corps operates and doesn’t let out any information or selectively lets out information they feel people can handle. They need to be able to come to people and say, ‘Hey, let’s sit down and talk about this so that we can form some kind of unified approach to keeping the dam safe.’” 

The bureau's original auction was open only to qualified oil and gas operators; the Corps, which controls the dam, gave its blessings to the deal although it's already working to repair the dam, described in local news reports as the eighth most hazardous in the nation. Highland Village, Hickory Creek and Lewisville all opposed the auction, and the towns and others lodged 500 letters of protest. One of those letter writers was Bartz, whom Hickory Creek had asked to study the dam.

Bartz wrote that allowing fracking under the lake is a bad idea, since “the Lake Lewisville area is surrounded by three major fault-causing events.” Activities associated with hydraulic fracturing, or fracking, have been linked to a rash of earthquakes in Texas and other states, and Bartz says the threat of human-induced quakes needs more study. He found similar fault lines near Somerville Lake, Lake Conroe and Choke Canyon, all Texas reservoirs that had parcels on BLM’s auction block.  The BLM, citing the need to evaluate public feedback,  canceled its plans for leases at all four of the reservoirs. Yet Bartz still hasn’t heard from the BLM or the Corps about his findings.

Like several other Dallas-based geologists who have protested plans to build the Marvin Nichols reservoir on a major fault line in Northeast Texas, Bartz fears that the added weight of water impounded in reservoirs like Lewisville Lake also could be putting pressure on a dormant fault. He claims Texas has already seen fault movement at Lewisville Lake's dam, though a spokesman for the Corps disputes that.

“When we get that strong probability [of fault movement] that means we have to devise the method to determine what really causes a catastrophic failure associated in the area with structural instabilities,” Bartz says.

Bartz says he discovered that Lewisville Lake's dam intersects with several geological features associated with active underground faults. Drilling activity “may result in an earthquake and cause expensive structural damage to the dam,” he wrote to the agencies. “Such damage could result in a breach of the dam and impact downstream residents.”  

A report released this spring by the U.S. Geological Survey said that human activity has increased the chance of potentially damaging earthquakes — up to magnitude 6 or 7 —  in areas where fracking is common, including Texas.

“An earthquake of that predicted magnitude and associated with a structural element beneath the Lewisville Lake dam could cause catastrophic effects to both the human and economic municipal entities that depend on Lewisville Lake’s flood control and water supply,” he wrote to the BLM and Corps.

Clay Church, a spokesperson for the Corps, wrote in an email response to questions from the Observer that his agency is is aware of Bartz and his findings but didn’t elaborate about what the agency planned to do about them.

Bartz says seismic monitoring should be conducted now at drill sites near Lewisville Lake and Lake Grapevine. Church says the Corps might consider monitoring, depending on what's happening on the ground.

“In the event active drilling is indicated at the project and seismic events occur more frequently in close proximity to the dam, then seismic monitoring would be considered,” Church says.

Donna Hummel, a spokesperson from the BLM, confirmed that the Lewisville Lake parcels were removed from the April sale and could possibly be leased in the future. At this point, anyone wishing to lease the land at Lewisville Lake would need to start the entire process over again.  If that happened, the public would have several opportunities to comment, and 2018 would be the earliest the parcels would be available for lease, she says.

The Center for Biological Diversity, an environmental organization, has been fighting the BLM’s quest to auction federal land for fossil fuel. Wendy Park, a staff attorney for the center,  says she would be surprised if the BLM decides to pursue leases at Lewisville Lake because there was so much public opposition.

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Christian McPhate is an award-winning journalist who specializes in investigative reporting. He covers crime, the environment, business, government and social justice. His work has appeared in several publications, including the Dallas Morning News, the Fort Worth Star Telegram, the Miami Herald, San Antonio Express News and The Washington Times.