Wayland Patch 3/24/12: Symposium Will Teach Protection of Local Water Supply. Residents are invited to the third annual Cochituate Watershed Symposium, sponsored by the Lake Cochituate Watershed Council, this Saturday to learn about the watershed, invasive species and how storm water runoff can impact the town's water supply. Natick, Ashland, Wayland, Framingham and Sherborn all share the 17 square-mile watershed.