Last year, the agency issued emergency regulations that prohibit fires, camping, glass containers, generators and radios. It has also enforced rules restricting the hours the area is open, provided garbage containers and portable bathrooms, and deployed forest rangers to watch over the site. In June, the agency issued a statement saying the Blue Hole, where people typically swim through September, was “overused.”

On Saturday, rangers on Route 42 directed people to 11 parking areas spread over nearly four miles that can collectively accommodate about 100 vehicles. Those pulling over on the side of the road were told they could not remain.

Kelly R. Turturro, a regional director for the Conservation Department, said that enforcing the parking rules was one way to make sure visitors would not overwhelm the Blue Hole.

Recently, members of groups like the Catskill Conservation Corps and the Adirondack Mountain Club arranged for a volunteer cleanup day at the Blue Hole. And the Leave No Trace Center for Outdoor Ethics designated it this year as one of 16 spots that had been negatively affected by recreational use. Ben Lawhon, the education director for the center, which is based in Boulder, Colo., said the group wanted to provide visitors with a framework for how to minimize their impact on wilderness areas.

On Saturday, two trainers from Leave No Trace stood at the beginning of a dirt path that led to the Blue Hole and spoke with visitors from Brooklyn, Newark and Hackensack, N.J., about conservation. They also gave out material, including plastic garbage bags; instructions for keeping wild areas clean, with hints like “trash your trash and pick up poop”; and stickers with an illustration of a furry figure and the words “Bigfoot’s been doing it for years. Leave no trace.”