Seattle Public Utilities

Landsburg Fish Passage Facilities

The construction of the Landsburg Diversion Dam on the Cedar River in 1901 created a barrier to salmon and other migratory species in the basin. An additional barrier was created just downstream of the dam by the City’s large water supply aqueduct. These facilities were built to provide a reliable supply of high quality water to the City of Seattle and surrounding area. At the time, little attention was given to the effects of these facilities on aquatic resources. In 2003, as part of the Habitat Conservation Plan and the Landsburg Mitigation Agreement, these barriers were removed and migratory fish were again allowed access to habitat above the aqueduct and dam.

  • Full channel, bolder/chute fishway before and after.
  • Tip-out gate at diversion dam.
  • A drawing showing how the "V" screen safely diverts fish from the water intake.

Reestablishing fish passage into over 17 miles of high quality mainstem and tributary habitat in Seattle’s Municipal Watershed upstream of Landsburg Dam is a key component of salmon recovery efforts in the Lake Washington Basin. The four Landsburg fish passage facilities at the dam and aqueduct crossing were completed in 2003:

  1. A full channel, boulder/chute fishway to provide easy passage over the aqueduct and improved habitat conditions.
  2. A fish ladder and sorting facility at the diversion dam to provide passage for adult salmon and steelhead, adfluvial and resident rainbow and cutthroat trout and other migratory species. Because of their much higher numbers, sockeye can pose a risk to drinking water quality. Sorting facilities at the ladder allow the exclusion of sockeye from above the dam.
  3. A tip-out downstream passage gate at the diversion dam to provide safe passage for downstream migrating fish as they pass.
  4. Special screens on the municipal water intake to route downstream migrating fish safely away from the water intake and back into the river.

The number of fish passing above the dam has generally increased since construction of the passage facilities in 2003. Monitoring suggests that fish are performing well in this new habitat and recolonization is occurring. For more information see the salmon recolonization page.

Landsburg Mitigation Contact

Michele Koehler, Aquatic Resources Manager
Seattle Public Utilities
Phone: (206) 733-9447