Sources of Seattle Water

The upper Cedar River is located in Southeast King County along the west slope of the Cascades. Numerous Rivers drain into Chester Morse Lake (1620 acre) reservoir is regulated by Masonry Dam built in 1916. Masonry pool, immediately west of Chester Morse Lake, serves as an additional impoundment. Water typically passes through Masonry Dam through penstocks driving two turbines. The Cedar River then flows downstream 12 miles to the Landsburg Diversion Dam (river mile 21.9) which was originally built in 1901. At the Landsburg Dam facility, a portion of the river flows is diverted from the Cedar for water supply. The water is screened, disinfected by chlorination, and fluoridated. Water is then conveyed outside of the watershed to Youngs Lake through a tunnel for municipal water uses and industrial uses. The City of Seattle provides the water to residents in the City and to other municipal jurisdictions (26 different purveyors) through contracts. Flows not diverted for water supply continue from Landsburg to Renton and discharge into Lake Washington. Minimum in-stream flows are required at Renton for fisheries resources and for operation of the Ballard Locks. Any water withdrawals from the Cedar River for drinking water purposes will have an effect on instream flows downstream. Description from , illustration from


  1. seattle water
  2. spu
  3. chester morse lake
  4. item 7711
  5. cedar watershed
  6. landsburg


Seth says

This (pipe vent) was found at Landsburg park.  It is probably above the other end of the pipe found leading to the Lake Youngs.  The board on it reads "Do Not Enter Pipeline Right Of Way" ... but who are they kidding ... there is no way you can get in there.

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