All that area west and north of a line commencing at the junction of the Putnam-Westchester county line and the Somers-Yorktown town line; thence southerly along the town line to the New Castle town line; thence clockwise along the New Castle town line to the Saw Mill River Parkway; thence northeasterly along the Saw Mill River Parkway to Route 117; thence southerly along Route 117 to Dixon Road; thence southeasterly along Dixon Road to Springhurst Road; thence southerly along Springhurst Road to McLain Street; thence westerly and southerly along McLain Street to Knowlton Avenue (Guard Hill Road); thence westerly along Knowlton Avenue to the Mount Kisco village line; thence southerly along the Mount Kisco village line to the Bedford-New Castle town line; thence southerly and easterly along the Bedford town line to the Delaware Aqueduct of the New York City Department of Water Supply, Gas and Electricity; thence southerly along said aqueduct to Route 120; thence northerly along Route 120 to Route 22; thence southwesterly along Route 22 to the Bronx River Parkway; thence westerly and southerly along the Bronx River Parkway to the Greenburg-Mount Pleasant town line; thence westerly along the town line to Broadway; thence northerly along Broadway to Old Croton Road; thence northerly along Old Croton Road to the North Tarrytown village line; thence westerly, northerly, and westerly along the village line to the east bank of the Hudson River; except that area delineated as Level III.