COLCHESTER, Vt. — New Vermont rules that require towns to build and maintain roads in a way that helps the state meet clean water requirements are going to be expensive for those communities, experts said on Monday.

The law requires municipalities to take on costly upgrades to roads that run near rivers and wetlands. For the first time the Agency of Natural Resources will have oversight over how towns maintain their roads, all part of an effort to prevent runoff into the state’s rivers and lakes.

“It is a big change,” said Department of Environmental Conservation Municipal Roads Program Coordinator Jim Ryan. “We won’t sugarcoat things. It’s a big change for all of us.”

Ryan said the state would offer some help, but towns will be expected to take on some of the load.

“It will take some significant funding to implement a lot of these practices that DEC’s going to require towns to implement,” he said.

Vermont Public Radio reported that the state’s clean water law requires towns to upgrade their culverts and ditches in an effort to reduce pollution from phosphorous runoff. The clean water measure also created a permit system and statewide map to monitor roads that have to meet the new standards.

Gwynn Zakov, who works as a municipal policy advocate for the Vermont League of Cities, said the clean water law was written without an understanding of long term costs. Zakov also said towns contribute less runoff than farms but the state hasn’t found a solution to agricultural pollutants.

“I think our towns would really like to know what the long term costs are going to be,” said Zakov. “If it’s not substantially funded by the state or the federal government these costs pretty much become unfunded mandates on our municipalities.”