An overfilled underground storage tank is the cause of a gasoline spill into the Popo Agie River in Lander according to a Friday filing from the Wyoming Department of Environmental Quality.

The leak was first discovered April 2 when the Lander Fire Department was dispatched to the Lander Maverik Country store after receiving complaints of gasoline vapors. Firefighters discovered an oily sheen on the surface of the river, which flows near the store.

LFD firefighters placed spill containment and absorbent booms in the affected area of the river, near the intersection of First and Main Street. The Environmental Protection Agency was also called to the scene along with local agencies.

After several tests, the DEQ is confident that Maverik overfilled one of its underground gasoline storage tanks. Maverik turned over inventory documents to the DEQ on Thursday which reflect a tank being overfilled.

The DEQ subsequently ordered that the gas station cease operating its pumps until adequate repairs are made to the tanks.

Maverik has 10 days to appeal the complaint.