Watershed groups, individuals, and land management and regulatory agencies are collecting streamtemperature data in order to understand, protect and enhance cold-water fisheries. While great quantities of data are being generated, its analysis and interpretation are often not adequate to identify stream reaches that are gaining or losing temperature, or to correlate temperature changes with factors such as vegetative canopy cover or stream-flow levels. We use a case study from the Lassen and

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... low creek watersheds in northeastern Modoc County to demonstrate graphical methods for displaying, analyzing and interpreting stream-temperature data. Glossary: stream-temperature metrics Daily maximum temperature: Maximum of 48 observations collected every half hour during each 24-hour day. Daily average temperature: Average of 48 temperature observations collected every half hour during each 24-hour day. 7-day running average of daily maximum temperature: Calculated for each day as average of daily maximum temperature observed for that day and for 6 consecutive prior days. 7-day running average of daily average temperature: Calculated for each day as average of daily average temperature observed for that day and for 6 consecutive prior days. Maximum weekly maximum temperature: Maximum 7-day running average of daily maximum temperatures observed during a period of interest (such as a specific month or critical fish life stage). Maximum weekly average temperature: Maximum 7-day running average of daily average temperatures observed during a period of interest. Data gathered from stream monitoring can be useful for formulating workable plans to safeguard cold-water fisheries. Ken Tate, UCCE rangeland watershed specialist, uses a solar pathfinder to estimate the percentage of available sunlight reaching a stream.