Discussions are ongoing regarding these cuts, which are expected to include grants to states aimed at protecting air, water and land.
The source points out that if there are massive layoffs at the EPA, it could have a big impact on military veterans employed by the agency, since vets are given preferential treatment in the EPA hiring process.
The source also points out a large portion of EPA's budget goes to contractors.
"A lot of small businesses are going to be impacted" if the proposed budget is adopted, the source said.
Neither the EPA nor the White House have responded to CNN's requests for comment.
Axios first reported
the additional cuts.
Two sources told CNN in February
that President Donald Trump might propose slashing as much as a quarter of the EPA's budget, a cut that one former EPA official said would be "devastating."
Trump and his aides announced a budget blueprint that boosted defense spending by $54 billion while slashing non-defense programs by the same amount. While details on the budget cuts weren't provided immediately, sources in the administration said that the EPA would be the main target.
Members of the Senate Environment and Public Works Committee had mixed reactions to the news of potentially deeper cuts.
Sen. Tom Carper, the top Democrat on the committee, said he had not personally heard that such cuts may be in the works, but blasted the idea of further reducing the EPA.
"It's already been reduced in the last several years and the idea of further deep cuts is crazy," he said. "Did I say crazy? Crazy."
Democratic Sen. Sheldon Whitehouse of Rhode Island called the White House budget an "act of political theater."
"So I expect they will try to make theatrical cuts, but ultimately the funding for the EPA is going to be determined by the appropriations committee and/or Congress in a big showdown," he said. "I think we're going to work very hard to defend EPA, and this little piece of political theater will slip into the past."
Republican Sen. Dan Sullivan said he's waiting to look at the budget when it comes out, but added "there's been a lot of different rumors" floating around.
"I think programs that go to the states that help for example with clean water and sewer for small communities, to me, are very important," he said.
When the budget cuts were first proposed, there was widespread concern within the EPA that the changes would dramatically alter the function of an agency that was created under Republican President Richard Nixon in 1970.
And the head of the EPA, Scott Pruitt, took an adversarial stance against the agency when he was Oklahoma's attorney general. Pruitt, whose nomination and subsequent confirmation were protested by several current and former EPA employees, sued the agency he now leads more than a dozen times in his previous role.