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One of the first efforts of the Agricultural Drainage Assistance Program upon its inception in 1998 was to find how many watercourses (including ditches, streams, and ditched streams) are located within the county's agricultural zones. Existing knowledge and reconnaissance from the public road system and from the air resulted in an initial picture of the watercourses, and this information was combined with existing knowledge of fish presence and absence.

The total combined length of all these watercourses (excluding the rivers) in all five APDs is about 300 miles (480 km). These distances break down to the following by APD:

  • Enumclaw, 151 miles (243 km)
  • Snoqualmie, 105 miles (169 km)
  • Upper Green River, 20 miles (32 km)
  • Lower Green River, 13 miles (21 km)
  • Sammamish, 10 miles (16 km)

The maps attached here, including an overview of the entire county and the five agricultural zones (Snoqualmie, Sammamish, Lower Green River, and the Upper Green River/Enumclaw APD) depict all the watercourses. Nothing is implied in these maps about the presence or absence of salmon or trout, about the class or type of watercourse, nor about whether a watercourse is a stream, a ditch, or a ditched stream.

View maps of King County Agricultural Production Districts (jpeg format):

For questions about the Agricultural Drainage Assistance Program or ADAP, please contact Brian Sleight, Supervising Engineer, King County Stormwater Services Section.