Real-Time Stream Flow Management

As part of the HCP, the City has committed to implement a new guaranteed flow regime based on more than 10 years of collaborative research analysis. This regime includes minimum and supplemental stream flows and limits the rate at which stream flows may be reduced at any given time.

In addition, the HCP places limitations on the City's future diversions to maintain sufficient management flexibility to adapt and further improve stream flow management practices as new information becomes available. The following graphs illustrate the guaranteed flow regime immediately below the Landsburg Diversion Dam and approximately 21 miles downstream at Renton.

Guaranteed Flow Regime below Landsburg (pdf)
Guaranteed Flow Regime Adjusted to Renton (pdf)

Water managers and biologists monitor stream flows continuously throughout the year to ensure compliance the guaranteed flow regime. The graph available at the link below provides an illustration of the guaranteed flow regime and actual flows observed during the most recent calendar year.

2011 Compliance Flow Graph
Compliance Summary 2000 – 2011
For much of the year, stream flows are naturally higher than the guaranteed flow levels. At these higher flow levels, the City's ability to influence flows is somewhat diminished, but remains significant. To best manage the system during these frequent periods of relative water abundance, the City will consult with the Instream Flow Commission, and use information from past and ongoing studies to make flow management decisions. The following bar graph provides a simplified picture of the annual allocation of Cedar River water.

Water Allocation Bar Graph (pdf)

Instream Flow Contacts

Water Management Section Manager
Tom Fox
Seattle Public Utilities
Phone: (206) 386-4041
tom.fox@seattle.gov

Senior Fisheries Biologist
Rand Little
Seattle Public Utilities
(206) 684-5925
Email: rand.little@seattle.gov