Greenwood Lake officials are taking zero chances with the discovery of what's believed to be harmful algae in the lake's north arm, temporarily banning boating and kayaking in that part of the lake.

Jim Martin sent the New York State Department of Environmental Conservation a video of what appeared to be harmful algal blooms since they slid through the holes in his skimmer, unlike non-harmful algal blooms that have a more solid consistency. The video, taken by the dock behind Martin's home on July 25, led the DEC to confirm on its online NYHABs map that harmful algal blooms are in the lake's northern arm.

Martin, a member of the bi-state watchdog group the Greenwood Lake Commission, said the algae may have been fed by the recent heat and the many substances that slide down the mountains on both sides of the lake.

"All the runoff — including from the Jenning's Creek Fire last year — went into the lake, is causing more nutrients to grow more weeds and algae," Martin said.

Upon learning of the potential for harmful algae in the northern arm, Mayor Tom Howley closed the north arm's kayak launch "out of an abundance of caution," and then went to check on the beach at Thomas Morahan Waterfront Park, a gem for locals and a draw for tourists.

Howley, who has been checking the beach three times a day, said the beach area is algae-free, and there are no other reports of harmful algae outside the lake's north arm. He said a contractor will survey the edges of the lake next week for the blooms. The north arm is more prone than the rest of the lake to becoming stagnant, a good environment for algae. The mayor is asking village residents to photograph and report anything they think might be harmful algal blooms.

"We do expect algae growth up there," he said Friday at Village Hall. "It's just a matter of watching it closely, and keeping the public informed." Howley has also been seeking grants to help the village fund long-term projects to eradicate algae and invasive weeds that have been growing rapidly in the north arm. He said the village is still the destination it has always been. He is trying to keep it that way.

"We love our visitors. We love our residents enjoying what we can offer," he said. "Rest assured, we're going to be monitoring that beach ... and if anything should change, we'll make the proper notifications to everybody." The Greenwood Lake Commission members and other environmentalists are waiting to see if, and how much, algae appears once the area experiences another stretch of intense heat.