(AP) — House and Senate leaders reached agreement Monday on a bipartisan bill to authorize $170 million for Flint, Michigan, and other cities beleaguered by lead in drinking water, and to provide relief to drought-stricken California.

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A vote on the water-projects bill could be held this week as Congress wraps up its legislative work for the year.

But the measure was jeopardized by sharp opposition from California Sen. Barbara Boxer and other Democrats who said it would harm drinking water quality and severely weaken the Endangered Species Act, threatening salmon and other endangered species.

House Majority Leader Kevin McCarthy, R-Calif., said the $558 million measure would bring more water to his state for farming and other uses. He hailed support from California’s other Democratic senator, Dianne Feinstein, saying the agreement could not have been reached without her backing.

“After years of hard work with countless constituencies, Congress is ready to pass a California water deal,” McCarthy said, calling the bill “an important moment for the state.”

Feinstein also defended the bill. While not perfect, “I do believe it will help California and it has bipartisan support including Republicans and Democrats in the House, and that’s why I’m supporting it,” she said in a statement.

“If we don’t move now, we run the real risk of legislation that opens up the Endangered Species Act in the future, when Congress will again be under Republican control, this time backed by a Trump administration,” she said.

Boxer, who is retiring at the end of the year, vowed to fight the bill until the minute she leaves office. At a news conference Monday, an impassioned Boxer called the agreement a “devastating maneuver” and “a last-minute backroom deal” that could do irrevocable harm to her state.

Boxer argued that the measure would “bypass the science” that forms the basis of the Endangered Species Act in order to direct that water be diverted to agriculture and other uses instead of protecting salmon and the imperiled Delta smelt.

She accused McCarthy of an “outrageous attempt to undo one of our landmark laws in the dead of night.”

With Congress set to adjourn for the year as early as Friday, Boxer said she would use procedural moves to delay the bill, up to and including killing other must-pass legislation such as a short-term measure funding the government until early next year. Congress faces a Friday deadline for the bill to avoid a government shutdown.

“We may be here through Christmas and New Year’s Eve,” Boxer said.

Boxer deflected questions about Feinstein’s role in the agreement, saying she and her veteran colleague have long disagreed about a drought remedy.

While the pair agree on “98 percent” of issues, “we have a big disagreement on this,” Boxer said.

Under an agreement reached Monday, the water-projects bill would include language authorizing aid for Flint and other cities, but money for the bill would be included in the short-term spending bill.

Flint’s drinking water became tainted when the city switched from the Detroit water system and began drawing from the Flint River in April 2014 to save money. The impoverished city was under state control at the time.

Regulators failed to ensure the water was treated properly and lead from aging pipes leached into the water supply.