The Ashland Dam and Spillway is a historic site at the north end of Ashland Reservoir in Ashland State Park in Ashland, Massachusetts. Ashland Reservoir was constructed in 1885, impounding a portion of Cold Spring Brook, a tributary of the Sudbury River. The dam and spillway were built as part of Boston's second major water works effort, which impounded large portions of the upper Sudbury River. They were listed on the National Register of Historic Places in 1990.