Aquarion Water Company is reporting an increase in unlawful winter recreational activities on reservoir properties.  The company is warning people not to trespass, including walking on reservoir ice because not only is it illegal, but it is also dangerous.  At this time of year, ice may appear thick enough to walk on, but Aquarion officials say this thickness is unreliable, and can be deceptive due to shifting water levels and thermal undercurrents.  Aquarion does allow the public on Centennial Watershed State Forest’s Saugatuck and Aspetuck Valley trails, which are open for hiking, cross country skiing and snowshoeing year-round for those who hold a valid permit.