INDIAN ISLAND, Maine — Penobscot Nation Chief Kirk Francis said Thursday that the tribe has “mixed feelings” about a federal judge’s ruling that its reservation includes the islands on the main stem of the Penobscot River but not the water itself.

U.S. District Judge George Singal also ruled Wednesday that members of the tribe may take fish from the entirety of that section of the river for sustenance.

“The court’s ruling that the tribe’s reservation boundaries for sustenance fishing are ‘in the entire main stem of the river’ is a significant victory,” Francis said in a press release issued late Thursday afternoon.

“It also appears that those boundaries apply to our hunting and trapping rights and authorities,” he said.

“Other language in the opinion stating that the reservation is confined to island surfaces has generated a lot of concern within our membership, so we are exploring our options for reconsideration or appeal,” he added.

The tribe could appeal Singal’s decision to the 1st U.S. Circuit Court of Appeals in Boston. Its attorneys have 60 calendar days to file a notice of appeal with the court.

Singal’s rulings came more than three years after the tribe filed a lawsuit against the state as a result of former Attorney General William Schneider sending a letter dated Aug. 8, 2012, to the tribal warden service saying that the state, not the tribe, has the authority to charge people with violating fishing regulations and water safety rules.

The tribe alleged in the lawsuit that its reservation includes the water in the river because of the tribe’s sustenance fishing rights. A year later, municipalities along the river were granted intervenor status in the case and supported the state’s contention that the reservation included the islands but not the water. The municipalities claimed that a ruling in the tribe’s favor would give it control over water quality on the river and allow the tribe to impose stricter rules than the state does on municipal discharges into the river.

Francis said in Thursday’s press release that tribal members are concerned about what, if any, effect Singal’s decision will have on a separate lawsuit over water quality standards in the Penobscot River being handled by U.S. District Judge Jon Levy.

Last year, the state sued the U.S. Environmental Protection Agency over water quality in tribal waters. The EPA has asserted that Maine’s water quality protections, when applied to unspecified tribal waters, must be based on factors such as fish consumption rates and risk levels that are different from those already approved by EPA that are used for the entire state, the Maine attorney general’s office said earlier this year in a press release.

The state has claimed the EPA created a double standard for water quality in Maine — one for tribal waters and another for the rest of the state.

Francis said in Thursday’s press release that the state’s water quality standards “do not adequately protect the quality or quantity of fish necessary for Penobscot member sustenance.”

Mark Chevaree, staff attorney for the Penobscot Nation, said Thursday that Singal’s decision “strengthens the foundation for EPA to protect water quality in the Penobscot River.”

Francis emphasized in the press release that the cultural identity of the Penobscot people ”is tied to our sustenance practices on the Penobscot River.”

“Our family names, our language, our creation stories, all aspects of who we are as a people come from our relationship to the river,” he said. “We could not stand by and let the state sever those ties.”