Cook County voters on Tuesday appeared to have approved a property tax hike for the forest preserves.

In a referendum on the ballot, property owners were asked to contribute on average about $1.50 more in property taxes per month toward the preserves, or around $20 a year. About $3 to $4 of a homeowner’s current property tax already goes to the forest preserves each month.

As of Wednesday, unofficial election results show voters overwhelmingly approved the referendum in Cook County, with about 2 out of 3 voters supporting it.

“With the results we see tonight on the referendum, it’s clear that people deeply appreciate all the benefits the Forest Preserves of Cook County provides, starting with access to nature so close to home. It’s exciting to see,” Arnold Randall, general superintendent of the Forest Preserves of Cook County, said in a statement. “Our work begins tomorrow on enacting plans to expand ecological restoration work, add more land to the preserve system, address critical long-term needs, continue to grow our programming and public outreach, and more.”

County leaders estimate the tax increase would generate just over $40 million in additional funding a year. They say the extra cash would help the county tackle ambitious goals, such as acquiring nearly 3,000 additional acres to protect it from development, restoring some 20,000 more acres over the next 20 years and putting more money into workers’ pensions.

The county’s forest preserves are one of the largest in the U.S., with nearly 70,000 acres of natural areas where people can hike, fish, bike, camp and even zipline. The Brookfield Zoo and Chicago Botanic Garden sit on forest preserve land.

County officials and more than 150 organizations that championed the referendum also tout the environmental benefits of the preserves, such as absorbing rainwater during storms and creating cleaner air.

Getting the referendum on the ballot took years, despite advocates and some county commissioners sounding the alarm that the forest preserve district didn’t have enough resources. The district is a separate unit of government from the county — with a roughly $140 million annual budget compared to more than $8 billion at the county — and is capped by how much property tax it can collect. Yet property tax revenue is the district’s main source of income.

Toni Preckwinkle, who doubles as president of the separate forest preserve district and Cook County boards, finally overcame her resistance to the referendum last year.

This story has been updated to correct a sub-headline that incorrectly stated the average total increase. It’s $1.50 per month.

Kristen Schorsch covers public health and Cook County for WBEZ. Follow her @kschorsch.