Three environmental groups that are suing Honolulu over its repeated sewage spills may become parties to a 1995 consent decree that requires major sewer repairs, a federal judge has ruled.

The decision moved the Sierra Club, Hawai'i's Thousand Friends, and Our Children's Earth Foundation closer to taking a direct role in guiding and ensuring such repairs until the decree with the city, U.S. Environmental Protection Agency and state Department of Health expires in 2019.

But Thursday's ruling by U.S. Magistrate Judge Kevin S.C. Chang stopped short of immediately granting the groups power to help enforce the consent decree's provisions through the courts.

They would have to seek additional court approval to assume such a role, and convince a judge that the government agencies aren't sufficiently enforcing the decree.

The groups have long been unsatisfied with the pace of repairs and upgrades, citing continuing sewage spills as evidence of neglect. The city had opposed their intervention in the consent decree and argued that they could derail a comprehensive settlement over Honolulu's sewage woes.

"Mayor Mufi Hannemann has every intention of continuing our good-faith negotiations with the EPA and DOH, as we have been over the past year, and giving the court no reason to believe that intervention by the court is necessary," said city spokesman Bill Brennan.

The ruling shows the judge wants the groups "to join all of us at the negotiating table, instead of going to court all of the time," he said.

Jeff Mikulina, director of the Sierra Club's Hawai'i chapter, said the group was pleased with the decision. "I think our interest kind of transcends the typical four-year terms of elected officials in really looking at the long-term health of the system," he said.

Yesterday, the city formally entered a separate court agreement with the EPA and DOH that requires an estimated $300 million worth of additional sewer projects.

Among them is replacement of a major Waikiki pipe that ruptured last year and triggered the release of nearly 50 million gallons of raw sewage into the Ala Wai Canal.

The City Council last week approved the deal, which also requires inspections or replacement of pressurized pipes at Ala Moana, Hart Street, Kane'ohe /Kailua, Waimalu and Kahala.

"This agreement will result in measures by the city to prevent catastrophic spills from O'ahu's most vulnerable sewage pipes," said Wayne Nastri, the EPA's administrator for the Pacific Southwest region.

The EPA indicated it would continue to negotiate with the city over a settlement to the city's sewage problems.

Hannemann is worried that the city will be forced to upgrade the Sand Island and Honouliuli sewage treatment plants, at a cost of over $1 billion.

The environmental groups had sued the city in 2004 after repeated sewage spills forced the closure of beaches and caused other problems. Most of their claims were dismissed a year later, in part because they mirrored claims in the EPA suit that led to the 1995 consent decree.

The groups then requested to intervene in that case to gain a role in enforcing its required repairs.

Reach Johnny Brannon at jbrannon@honoluluadvertiser.com.