Legal skirmishes are mounting as more U.S. municipalities, including four in Tuesday’s midterm elections, ban the controversial oil and natural gas drilling technique known as hydraulic fracturing or fracking.

Two lawsuits were filed Wednesday, only hours after 59% of voters in Denton, Texas, adopted the Lone Star state’s first fracking ban. The city, a 45-mile drive northwest of Dallas, sits atop the Barnett Shale, one of the nation’s largest natural gas fields and a prime fracking site. Fracking blasts huge volumes of water, mixed with sand and chemicals, deep underground to blast apart shale rock and release oil and gas molecules trapped in the ore.

The Texas Oil and Gas Association and the Texas General