Dog owners who let their animals run off leash at Amethyst Brook Conservation Area after 10 a.m. have started receiving warnings and will face fines for repeat offenses.

In November, the Conservation Commission voted to limit the hours for unleashed dogs in response to hikers and bicyclists who reported being attacked or harassed by them. Amethyst Brook in East Amherst is a popular dog walking area for people from many towns in the region, and the commission heard from many who opposed any leash requirement.

Many now let their dogs run free there only before 10 a.m., said Carol Hepburn, Amherst's animal welfare officer. But continued resistance to the new rules is evident in repeated vandalism of the signs detailing them at Amethyst Brook.

Temporary signs were torn down four or five times, said David Ziomek, the director of conservation and planning. Sturdier signs costing $27 apiece have been erected and torn down twice, he said.

On a recent afternoon, Ziomek and Hepburn spent an hour at Amethyst Brook with Briony Angus, who chairs the Conservation Commission. They spoke to five to seven people who had let their dogs off leash, he said.

Ziomek said the commission has asked him to encourage Hepburn to spend more time at Amethyst Brook and give official warnings to violators, he said. Hepburn reports to Police Chief Scott Livingstone, who is supportive of the effort to enforce the rules, Ziomek said.

The amount of the fine is $25, Ziomek said. The Conservation Commission plans to review the policy in May, he said.