In Koyuk, old fuel tanks left petroleum in the ground. Now someone will measure it.

Two old fuel tank farms sit in and beside the developed part of Koyuk, a village on Norton Sound, and the ground beneath at least one is contaminated with petroleum. For the first time, someone is going to find out how bad it is.

Kawerak, the Bering Strait region's Native nonprofit, has formally identified both — the Koyuk Old City Tank Farm on the north end, and the Koyuk Native Corporation Tank Farm, which carries an open contamination file in state records. A $300,000 EPA grant will pay to assess them and other sites across the region.

Koyuk is one village in a statewide pattern. Alaska has thousands of contaminated or potentially contaminated sites, and petroleum is by far the most common — much of it old bulk fuel, generators, and military infrastructure. A lot of it was left on land before that land was handed to Native corporations under the 1971 Alaska Native Claims Settlement Act, so communities often inherit contamination they had no part in creating.

Nothing at Koyuk has been sampled yet, and no health hazard is confirmed — this is the first step. But petroleum's worst compounds, like benzene, can reach drinking water, and in villages these sites tend to sit near where people live, hunt, and haul water. And identifying a tank farm is a long way from cleaning one up: in other Alaska communities, that road has run years, sometimes decades.

What the assessment finds will decide whether Koyuk's tank farms are cleaned up or put back to use, and when.