LONGMONT - Longmont voters' approval of a ban on the use of hydraulic fracturing to extract oil and gas could set off legal battles pitting mineral-rights interests against local governments' right of self-determination.

Ballot Question 300, approved by 59 percent of Longmont residents who voted in Tuesday's general election, would prohibit companies' use of the procedure popularly known as "fracking" within city limits, as well as forbidding storage of fracking waste in the city.

The procedure involves high-pressure infusion of fluid into deposits of rock deep beneath the Earth's surface to free up deposits of oil or gas for extraction. Supporters and opponents of fracking argue over its potential risk to groundwater and air quality.

The issue arose in Longmont in 2011 after Lakewood-based TOP Operating Co. announced plans to drill wells at two sites on the city's eastern edge. The city responded in July by tightening its oil and gas regulations, which included a ban on drilling in residential areas. That prompted a lawsuit by the state, which contended the action represented a "taking" of mineral rights. Longmont citizens, in turn, responded by petitioning Question 300 onto Tuesday's ballot.

Opponents of the ballot issue contended that the measure could pre-empt negotiations with the state and lead to another lawsuit. Supporters countered that no "taking" would be involved because drilling would still be permitted and the only restriction would be on the method used.

The Colorado Supreme Court has ruled that local governments can't ban drilling outright, but has considered lesser restrictions case by case.

Representatives of the Longmont City Council and the Colorado Oil and Gas Conservation Commission, which has authority over oil and gas extraction in the state, did not return calls for reaction by the Business Report's deadline today, and the Longmont city attorney's office refused comment.