Clear Creek Water Temperature Threshold Analysis

Ecological Thresholds Queries
Clear Creek Lower American River Sacramento River Stanislaus River

This page provides analysis — based on Reclamation 2025 Action 5 ROD (2026 to present), Reclamation 2019 Proposed Action (2019-2025) and RPA I.1.5 (2009-2018) — of current and historical water temperature conditions for fish using only observed data. Actual pre-season and in-season management decision processes are complex employing multiple sources of observed data, models, and forecasts. For further information, see the Thresholds section.

Note: Historical data only for years prior to 2009.
line plot water temperature and flow for Clear Creek
Line chart for 2026 Clear Creek daily average control regulating discharge at Whiskeytown (WHI), flow near Igo (IGO), and water temperature near Igo (IGO). Threshold lines for Juvenile Steelhead and Spring-run Chinook Adults at 61°F and 60°F and Spring-run Chinook Eggs and Pre-emergent Fry at 56°F. Water temperature (in degrees Fahrenheit) and flow in cubic feet per second (CFS). Data retrieved from CDEC; figure generated by SacPAS.
2026 Water Temperature Threshold Analysis and Exceedance
Life Stage Life Stage
Dates		 Criterion Possible
Days		 Data
Days		 Missing
Data
Days		 Total Period Analyzed Criteria Exceedance
Average
Water
Temperature		 Days in
Threshold		 Days First Day Last Day
Juvenile/Adults 6/1-8/15 Below/Equal 61°F 0 0 0          
Juvenile/Adults 8/16-9/15 Below/Equal 60°F 0 0 0          
Eggs/Fry 9/16-11/15 Below/Equal 56°F 0 0 0          

Daily Data

download Daily Data csv
2026 Clear Creek Water Temperature Threshold Analysis Daily Data Table
DateWhiskeytown Dam (USBR) (WHI) River Release cfs Clear Creek nr Igo (IGO) Flow cfsClear Creek nr Igo (IGO) Water Temperture FJuvenile/Adults 61F 6/1-8/15 StatusJuvenile/Adults 60F 8/16-9/15 StatusEggs/Fry 56F 9/16-11/15 Status
2026-01-28303.00317.5248.77
2026-01-27304.00317.2847.98
2026-01-26303.00318.2447.65
2026-01-25303.00319.3247.70
2026-01-24303.00321.4848.30
2026-01-23304.00323.9248.47
2026-01-22304.00327.6049.15
2026-01-21305.00330.0448.96
2026-01-20306.00332.9248.75
2026-01-19306.00336.6449.03
2026-01-18307.00340.4848.84
2026-01-17307.00344.9648.73
2026-01-16307.00352.2049.24
2026-01-15305.00358.4649.31
2026-01-14307.00366.3249.18
2026-01-13306.00375.9248.80
2026-01-12307.00388.6048.97
2026-01-11307.00404.7048.77
2026-01-10307.00432.5848.79
2026-01-09307.00467.9248.58
2026-01-08307.00538.0448.86
2026-01-07307.00668.8050.85
2026-01-06307.001053.0452.21
2026-01-05289.001534.2451.67
2026-01-04279.00749.4051.65
2026-01-03278.00734.1651.80
2026-01-02277.00509.0051.13
2026-01-01277.00368.1250.53

Data Methods & Notes

Methods

  1. Data Courtesy of CDEC and US Geological Survey
  2. Hourly data for Clear Creek nr Igo (IGO) is retrieved from CDEC on a daily basis.
  3. Columbia Basin Research (CBR) QA/QC process on IGO hourly data for outliers, false data (e.g., 32°F measured by satellite), and data outside expected range of observation (e.g., 90°F). Data loaded into CBR database.
  4. CBR calculates Daily Average values based on CBR cleaned hourly values.
  5. Query for daily average water temperature for selected year.
  6. Examine daily average data for 60°F and 56°F exceedance during date periods as outlined in Reclamation Proposed Action.

Thresholds

Please refer to the Clear Creek Technical Team (CCTT) annual reports for details on within water year activities.

Target analysis and exceedance found on this page is based on criteria as described in Reclamation 2025, p3-6.

Reclamation 2025. Action 5, Record of Decision, Attachment 1, Exhibit 1, Operation Plan for the Central Valley Project and State Water Project, Long-Term Operation of the Central Valley Project and State Water Project. December 2025. Available online: https://www.usbr.gov/mp/bdo/lto/

3.5 Water Temperature Management

Water temperature management addresses adult water temperature and egg incubation stressors. Reclamation would target Whiskeytown Dam releases to not exceed the mean daily temperatures at Igo gauge:

  • 61°F from June 1 through August 15
  • 60°F from August 16 through September 15
  • 56°F from September 16 through November 15

If two consecutive days of mean daily temperature are exceeded, and Reclamation determines additional water is available, then 25 cfs per day may be added to the base flow to address temperatures. Before spawning (in the late spring or summer) a return to base flow would occur when meteorological conditions allow. After spawning (later-summer or fall) flow changes for temperature management would be maintained until the base flow of the seasonal hydrograph rises to meet the elevated temperature release so as to avoid dewatering redds.

Water temperature management on Clear Creek is implemented through changes in guard gate configurations and flow manipulations. In dry, critical, or import curtailment years, Reclamation may not be able to meet these temperatures and would operate Whiskeytown Dam as close to these temperatures as practicable.