Water is sometimes spilled at Wells Dam to meet flood control requirements, or when river flows are beyond the capacity of electricity requirements or unit (turbine) capacity. Spilled water has the potential to entrain atmospheric gasses such as nitrogen, which can super saturate water with gases. Douglas PUD measures the gases in the water above and below Wells Dam as Total Dissolved Gas or TDG concentration in order to assess compliance with Washington State water quality standards. In addition, the Wells Dam juvenile bypass system (JBS) operates continuously from early April through late August and passes up to 2,200 cubic feet per second of water through each of the five JBS configured spillways. Under normal conditions the JBS will use roughly six to eight percent of the total river flow for fish guidance. The increased spill passed through the JBS has minor influence on TDG production (~0-2 percent) while providing a non-turbine passage route for over 90 percent of the spring and summer migration of juvenile salmonids. Finally, Douglas PUD monitors river water temperatures at the Dam and at Project boundary locations. Total dissolved gas and water temperature data is available on this page through a series of links below.
Water Temperature Stations Maintained by the USGS:
Chief Joseph Dam Tailrace
Okanogan River Mile 10.5
Methow River Mile 1.5
Wells Dam Forebay (Three depths: Surface, Middle and Depth)
Note the above stations (numbers 1-4) collect data in real time from April 1st - November 15th.
Douglas PUD Maintained TDG and Water Temperature Stations:
- Forebay (WEL): TDG/Temp data
- Tailrace (WELW): TDG/Temp data
- Washburn Island: TDG/Temp data (Columbia River Mile 537.5): TDG/Temp data
- East Fish Ladder - Pool 39: Temp data
- Auxiliary Water Supply Chamber - Fish Ladder Pumps: Temp data
Data for the above temperature and TDG stations (numbers 1-5) can be accessed by downloading the CSV file for the month or year of interest below. Data for these locations is collected year-round and in real time.
TDG and Temperature Data
If you have questions about the TDG and Temperature data, please contact us