Energy giant Kinder Morgan called a federal lawsuit filed by two Hays County groups last week “unfounded and without merit.” The lawsuit accuses the company of violating the Safe Drinking Water Act during construction of its Permian Highway Pipeline (PHP), a 430-mile natural gas pipeline that is carving its way through the heart of the Texas Hill Country.

Litigants allege that carcinogens were among the substances introduced into a karst feature fractured on March 28 as a contractor w...