The park is consistently full of leashed dogs and their owners on a weekend morning; it serves as an informal neighborhood social event. Note: No swimming is permitted in Sloan's Lake or any Denver lake : the ban dates to the polio epidemic of the 1950s and was never lifted. Water quality also involves street and park runoff. Second: keep dogs away from protected wildlife areas near the water, like white pelicans that migrate through the park in May and June, and are protected.