AUGUSTA — Lawmakers gave final approval Monday to a bill regarded as a key step in resolving long-standing disputes between the state and tribal governments over sustenance fishing rights.

The Senate voted 35-0 to pass a bill that would designate several dozen rivers, streams or other water bodies in Maine as “sustenance fishing” areas. Those waterways – including the Penobscot River north of Old Town and sections of the St. Croix, St. John and Aroostook rivers – would then have to meet tighter water quality standards to be set by the Maine Department of Environmental Protection.

The bill, which is now headed to Gov. Janet Mills’ desk for her signature, is designed to better protect the health of tribal members who consume more fish as they exercise their sustenance fishing rights. But the legislation also aims to begin to resolve costly and contentious legal battles between the state and tribes over water quality in waterways important to tribal members.

The Mills administration worked with leaders of the four tribes in Maine – the Penobscot Nation, the Passamaquoddy Tribe, the Houlton Band of Maliseet Indians and the Aroostook Band of Micmacs – to craft the bill creating a “sustenance fishing” designation in Maine’s water quality standards.

The bill, L.D. 1775, would order the DEP to set water quality criteria adequate to protect the health of tribal members that eat up to 200 grams, or roughly 7 ounces, of fish from those waterways each day. But DEP officials testified last month that the stricter standards should not significantly impact any of the 19 municipal wastewater treatment plants or private companies that discharge into the waterways because most are already meeting the standards.

Instead, the bill would prevent “backsliding” in the future while potentially helping bolster Maine’s push for other states to tighten up their pollution standards for mercury, which is the primary health culprit in Maine fish. Because of Maine’s geographic location, mercury pollution emitted by coal-fired power plants and industries in upwind states drifts into Maine before settling in state waters.

Existing mercury pollution levels mean that it would still be unsafe for tribal members to subsist on fish in many waterways. But supporters said the bill – when combined with dam removal/fish passage projects and other efforts – are all part of the long-range plan to improve water quality standards.

“We would love to get to the point where we can healthily live off of fish, like our ancestors did,” Penobscot Nation Ambassador Maulian Dana said last month during committee testimony on the bill.

The bill is one of several measures supported by the Mills administration to improve the long-fraught relations between state government and tribal leaders.