Uncertainty and the Management of the Cedar River Presented by Bruce Bachen, Rand Little, and George Schneider Water Management Section Seattle Public Utilities May 13, 2003

The Cedar River Water Supply for one million people Water Supply for one million people Key Habitat for chinook, coho, sockeye salmon and steelhead trout Key Habitat for chinook, coho, sockeye salmon and steelhead trout Site of the largest sockeye run in the state, and the Landsburg sockeye hatchery Site of the largest sockeye run in the state, and the Landsburg sockeye hatchery

Stream Flow Management: Protecting Instream Resources Seattle’s water storage and diversion activities have a substantial effect on stream flows in the lower Cedar River Seattle’s water storage and diversion activities have a substantial effect on stream flows in the lower Cedar River Stream flow is a key component of the aquatic/riparian ecosystem that supports salmon and many other species Stream flow is a key component of the aquatic/riparian ecosystem that supports salmon and many other species Social values and species protection priorities change over time Social values and species protection priorities change over time The applied science of stream flow management is complex, relatively new, and continues to evolve The applied science of stream flow management is complex, relatively new, and continues to evolve

Meet sockeye mitigation responsibilities by: Managing a hatchery to produce more sockeye and provide additional fishing opportunity while minimizing risks to naturally spawning salmon populations and the ecosystem

Water Management - Context Multiple Objectives Multiple Objectives Vulnerability Vulnerability Hydrologic Uncertainty Hydrologic Uncertainty

Multiple Objectives Create the Tension of Competing Demands Water Supply Water Supply Instream Flows Instream Flows Reservoir Management for Resident Species Reservoir Management for Resident Species Flood Control Flood Control Hydropower Hydropower

Vulnerability A Reflection of the Sensitivity of the System and its Beneficiaries (people and environment) to variable conditions A Reflection of the Sensitivity of the System and its Beneficiaries (people and environment) to variable conditions

Hydrologic Uncertainty-Imaginary World If the hydrology affecting the system were 100% predictable, the system could be operated “perfectly” If the hydrology affecting the system were 100% predictable, the system could be operated “perfectly”

Hydrologic Uncertainty - Real World Weather is highly variable and somewhat Weather is highly variable and somewhat unpredictable unpredictable Climate is variable and may be changing Climate is variable and may be changing Physical processes affecting hydrology are Physical processes affecting hydrology are complex complex

Strategies for Decision Making in the Face of Hydrologic Uncertainty Making Sense of the Past Making Sense of the Past Real-time Information Gathering Real-time Information Gathering Forecasting Forecasting Communication with Stakeholders Communication with Stakeholders Operational Flexibility Operational Flexibility Risk Sharing Risk Sharing

Making Sense of the Past Range of variability, statistical analyses Range of variability, statistical analyses Affords Comparisons to Current Conditions Affords Comparisons to Current Conditions and Development of Possible Futures and Development of Possible Futures Physical Processes and response of Watershed Physical Processes and response of Watershed Learning from Prior Successes and Failures Learning from Prior Successes and Failures

Real-time Information Gathering Weather Weather Water Use Water Use Fish and Wildlife Fish and Wildlife Snow Snow Streamflow Streamflow

Forecasting Weather Weather Streamflow Streamflow Climate, ENSO/PDO Climate, ENSO/PDO

Communication with Stakeholders Greater Knowledge of Conditions, Issues Greater Knowledge of Conditions, Issues and Values and Values Better Understanding of Consequences of Better Understanding of Consequences of Decisions Decisions Risk Sharing and Decision Sharing Risk Sharing and Decision Sharing

Operational Flexibility Dynamic Reservoir Rule Curves Dynamic Reservoir Rule Curves Hydrologically-linked Instream Flow Hydrologically-linked Instream Flow Obligations Obligations High Reliability Standard