The principal streams within the Valley are the Schoharie, Cobleskill, and Catskill creeks, and West and Manor kills. The main branches of the Delaware River originate in the southwestern corner of the county. Water is supplied by Schoharie, Blenheim Gilboa, and Upper Blenheim Gilboa reservoirs.

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Below are some of the maps that we have compiled that display the principal streams and surrounding watershed of the Valley.