With a quarter-billion-dollar funding gap plugged, there’s now enough money to extend the Foothill Gold Line from Glendora to Montclair.

The California Sate Transportation Agency announced Thursday it would award $290 million to the Gold Line extension to support the project on both sides of the Los Angeles-San Bernardino county line.

The 12.3-mile extension is currently estimated to cost $1.5 billion and has been funded on the Los Angeles County side by Measure M sales tax dollars approved by voters in November 2016. Based on earlier estimates, however, they weren’t going to be enough, and the project was facing a $250 million shortfall.

“This was a big milestone for us,” Metro Gold Line Foothill Extension Construction Authority CEO Habib F. Balian said of the grant. “But we can’t exhale just yet.”

The authority is moving forward with plans to hire the design-build contractor, Balian said.

In February, the authority short-listed four design-build teams to compete for the work. The authority is expected to issue a request for bids late next month, and a contract award is anticipated in October, according to the news release.

Balian said the construction bids will factor in changes since the estimates were provided, such as labor and tariffs.

“Once the bids come in, then we can exhale,” he said. “Based on our estimates, we are fully funded.”

Balian said the transit agency was one of several major projects in Los Angeles County to receive the requested grant award in full, resulting in a combined total of $1.09 billion.

“It proves what everybody has been saying all along: L.A. County, more than anywhere in the country, has been so invested in improving public transportation,” he said.

Balian said the authority collaborated with the Los Angeles County Metropolitan Transportation Authority and San Bernardino County Transportation Authority to apply for the grant, submitting the application in January. However there was no guarantee it would get all the money it was requesting, he said.

The Gold Line expansion is “tying into a great system” — it travels from Azusa to downtown then out to East L.A. — that has proven popular with San Gabriel Valley riders, Balian said .

Assemblyman Freddie Rodriguez, D-Pomona, who authored authored Assembly Bill 215, which added Montclair as a Gold Line extension city, applauded Thursday’s news.

“This is a huge investment in the Inland Empire that will benefit our businesses, workers, and families working hard every day to build a more sustainable and prosperous region,” Rodriguez said in a statement.