DENVER (CBS4) – Denver Parks and Recreation (DPR) released a statement on Thursday reminding visitors that walking or skating on frozen lakes or ponds in the Denver park system is prohibited.

DPR said the ice may appear to be thick enough, but the ice layer is actually very thin and unstable.

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“We’ve had many incidents over the past several weeks where people were walking or skating on frozen lakes in our parks around the city,” said Scott Gilmore, Deputy Manager of Parks and Planning for DPR. “These individuals are putting their lives at risk. The big swing in frigid and mild temperatures we see in Denver makes the ice layer on our ponds and lakes very unstable. It would be very easy for an adult or child to fall through the ice, creating a very dire situation.”

Over the past few weeks CBS4 has reported on several dogs that have died and others rescued after chasing birds onto a frozen pond or lake. Pets are required to be kept on a leash at all times.

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DPR says the leash law is in place for the animal’s safety as well as the safety of others.

“Sadly, in the last month we’ve had at least two separate instances where a family pet has drowned after falling through the ice in one of our parks,” Gilmore said. “This is a tragic outcome that could have been avoided had the animal been on a leash.”

The department is asking all park visitors to also be vigilant and to report any potential rule violations or safety issues to park staff on site or by calling the Denver Park Rangers hotline at (303) 331-4050.

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Anyone who witnesses an emergency situation that requires an immediate response should always call 911 right away. If you see an animal or a person fall through the ice, do not go in after them. Stay on land and call 911 and wait for emergency personnel to arrive.