Lake Ilsanjo

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Lake Ilsanjo
Lake Ilsanjo 10089.jpg
The lake in 2013
Lake Ilsanjo is located in California
Lake Ilsanjo
Lake Ilsanjo
LocationSonoma County, California
Coordinates38°25′37″N 122°38′00″W / 38.4269°N 122.6333°W / 38.4269; -122.6333[1]Coordinates: 38°25′37″N 122°38′00″W / 38.4269°N 122.6333°W / 38.4269; -122.6333[1]
Primary inflowsSpring Creek
Primary outflowsSpring Creek
Basin countriesUnited States
Max. length650 yd (600 m)

Lake Ilsanjo is a man-made lake located in Annadel State Park east of Santa Rosa in Sonoma County, California, United States. It is a place for fishing and swimming, especially in the summer months. Entrepreneur Joe Coney originally owned the land that is now Annadel State Park and named the lake after his wife Ilsa and himself. Thus it came to be called Lake Ilsanjo.[2] It drains into Spring Creek.

The lake is formed by a dam constructed in the 1950s. Originally the overflow drained to a gully during the winter months, but in 2003, the state spent almost $400,000 building a spillway and release valve to reduce downstream erosion. During the winter of 2007–08, park officials accidentally left the release valve open, causing the lake level to drop far below normal, exposing mudflats that would normally be underwater.[3]

See also[edit]


  1. ^ "Lake Ilsanjo". Geographic Names Information System. United States Geological Survey.
  2. ^ "Annadel State Park" (PDF). Archived from the original (PDF) on September 6, 2012. Retrieved October 11, 2012. CS1 maint: discouraged parameter (link)
  3. ^ "Lake accidentally lowered". Archived from the original on 2008-08-20. Retrieved 2008-03-29. CS1 maint: discouraged parameter (link)

External links[edit]