A federal agency has rejected New York’s application for $150 million for an ocean-outfall pipe at Nassau’s Bay Park sewage-treatment plant, further reducing the potential funding options for the multimillion dollar project.

The proposal was included in an entry the state made last year in a $1 billion national competition on disaster resilience run by the U.S. Department of Housing and Urban Development.

While New York State was among the competition’s winners announced Thursday, it received only $35.8 million to use on increasing resiliency in public housing statewide.

State officials repeatedly had touted the competition as a way to provide a third of the funding for the outfall pipe, which Nassau County officials said will cost $450 million to build.

The pipe would send nitrogen-rich effluent from the plant, which serves 500,000 people, into the Atlantic Ocean instead of the beleaguered Western Bays, a series of waterways that are part of the South Shore Estuary Reserve.

High levels of nitrogen in the roughly 50 million gallons of treated effluent per day that flow into Reynolds Channel have weakened the area’s coastal marshlands, which are considered crucial natural buffers against harsh wave action during storms.

“While it is disappointing that New York was not successful in securing additional funding in the National Disaster Resilience Competition, it is important that this project advance in a timely manner with previously announced state and local funding,” Basil Seggos, acting commissioner of the state Department of Environmental Conservation, said in a statement.

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Brian Nevin, spokesman for County Executive Edward Mangano, said the county also was “very disappointed.”

“Clearly, an award here would have made the ocean-outfall pipe possible,” Nevin wrote in a statement, adding the county would continue working with the state to find a way to build the pipe.

Assemb. Todd Kaminsky (D-Long Beach), also called the news “disappointing,” urging all players to “go back to the drawing board and find creative ways to fund this vital project.”

A source familiar with the application process said the pipe was a relatively hard sell in a competition focused mainly on projects that provide direct resilience against disasters — such as sea walls or berms.

“This is a harder project to be funded because it is a bit of a nontraditional project,” the source said, adding that another factor was the uncertain source of funding for the project.

The county has expressed a willingness to commit $150 million for the pipe, and the state has a pending application with the Federal Emergency Management Agency to use $150 million in Hazard Mitigation Grant Program funds for it.

And while Gov. Andrew M. Cuomo this month announced $5 million for the outfall in his proposed 2016-17 state budget, the funding still remains a tentative patchwork.

“No one wants to be the first dollar in, particularly when this is a competition,” the source said. “They want to put money into projects that are fully funded.”