About 1,700 acres in northwestern Connecticut are already protected under the federal Highlands Conservation Act, and this week a bill was introduced to reinstate and preserve federal funds to protect more land until 2021.

Though the act expired in 2014, Congress has allocated millions of dollars each year since to continue to protect land in the highlands region, which covers 3.5 million acres in Connecticut, New York, New Jersey and Pennsylvania. About 28 towns make up Connecticut’s region, including Danbury, Brookfield, Sherman, New Fairfield, New Milford, Kent and Washington.

Since the act was passed in 2004, Connecticut has received about $5.5 million in federal funds, said Graham Stevens, of the state Department of Energy and Environmental Protection, which administers the program locally for the federal government.

“It’s the single most important source of federal land protection money for Connecticut outside of the Farm Bill,” said Tim Abbott, the greenprint director for the

Housatonic Valley Association, which spearheads the highlands conservation effort in the state. “It’s indispensable.”

The act was used to protect former Girl Scout Camp Francis and the West Aspetuck Preserve, both in Kent, as well as Towner Hill and Eastman, both in Sherman.

However, Sen. Richard Blumenthal, D-Conn., one of the legislators who introduced the bill, said no money is allocated this year in President Donald Trump’s budget.

“That’s why we need to mount a full-court press,” Blumenthal said.

The bill was co-sponsored by Sens. Chris Murphy, D-Conn., Kirsten Gillibrand, D-N.Y., and Bob Casey, D-Pa.

Blumenthal said the lack of funding and the threat of development facing the region prompted them to submit the bill. Losing the natural landscape of the highlands would threaten the native species as well as the water quality.

“The creep of commercial and residential construction is heading north towards our Massachusetts border,” he said. “Our highlands are in jeopardy.”

Blumenthal said the program has a lot of congressional support.

Abbott has seen the evidence of this with the continued allocations. He said Connecticut has received more since the program expired than in the 10 years it was active. Last year, Congress authorized up to $10 million for the program — the maximum annual amount— awarding Connecticut about $2.4 million.

Even with this support, he said the bill is needed to ensure continued funding and reinforce a policy to administer the program.

He said the Highlands Conservation Act has been well received because it’s a public-private partnership.

The act requires a matching local donation for every federal dollar. For many, the state’s open-space grants help meet that figure and towns, land trusts and other organizations close the gap. For every highlands dollar spent, another $3.70 was generated.

Another benefactor, Rep. Rodney Frelinghuysen, R-N.J., chairs the House Committee on Appropriations and has been supportive of the highlands, which runs through his district, Abbott said.

Connie Mane, the executive director for the Kent Land Trust, said public-private partnerships are crucial for land trusts in Connecticut, where land values are so high and too expensive for a trust to purchase by itself. She said acquiring the former Girl Scout camp in 2014 wouldn’t have been possible without the highlands money.

“It’s absolutely critical that this program continue,” she said. “It’s having its intended effect and the return has been great.”

Blumenthal said preserving the land translates to economic development.

“Environmental treasures also have economic value,” he said. “They attract tourists and other kinds of resources that preserve and use the beauty of the land in a wise way.”

Stevens said most of the protected land is used for outdoor recreation, such as hiking.

“It certainly is a benefit to the community to protect the land in perpetuity,” he said.

Stevens said 800 or 900 acres are in line to be preserved if funding is approved.

“We’ve made great progress so far preserving the Highlands, but we have more work to do,” Murphy said in a statement. “This bill will go a long way in helping protect this critical ecosystem for centuries.”