A $511 million loan approved by a New York environmental agency to help fund the construction of a new $4 billion Tappan Zee Bridge was rejected almost entirely by the U.S. Environmental Protection Agency.

The loan approved by the New York State Environmental Facilities Corp. in June was meant to drive down borrowing costs for the new span across the Hudson River, with half of it being provided at zero interest. The state said it could use the funds from a program that targets clean-water projects.

The EPA said in a letter to state officials today that building a new bridge doesn’t fit the intention of the program, which is backed by federal dollars. The agency said only $29.1 million could be allowed.

“Construction activities arising from transportation projects do not advance water quality,” Joan Matthews, the regional director of the clean water division, wrote in the letter, which was posted on the EPA’s website. “No other state has made a request of this type or magnitude.”

New York Governor Andrew Cuomo, a 56-year-old Democrat, has made building a new Tappan Zee a priority, comparing it with the 19th-century construction of the Erie Canal. About 20 miles (32 kilometers) north of Manhattan, construction of the bridge is among the nation’s largest public-works projects.