Barometric Pressure: Barometric Pressure is atmospheric pressure at the site, given in mm Hg. It represents an average of hourly measures. Barometric Pressure is measured at Water Quality Monitoring stations in the forebay and tailrace of most projects (see Data Sites Map) and other key locations in the basin. Prior to 1995, the data are from a variety of sources within the U.S. Army Corps of Engineers.
Dissolved Gas: Dissolved gas is a measure of the pressure of dissolved gas in the water column. When spillway water plunges into the tailrace nitrogen is forced into the water at higher than normal levels. This condition, called supersaturation, occurs when dissolved gas pressure in the water actually exceeds the atmospheric pressure. The dissolved gas value represents a daily average of hourly meeasures within the range of 600-900 mmHg and is derived from U.S. Army Corps of Engineers gas monitoring efforts. Often collected at irregular intervals, this parameter may be missing values for one or more days, or reported values may be obviously incorrect. Dissolved Gas is measured at Water Quality Monitoring stations in the forebay and tailrace of most projects (see Data Sites Map) and other key locations in the basin. Prior to 1995, the data are from a variety of sources within the U.S. Army Corps of Engineers.
Dissolved Gas Percent: Gas percent reflects the degree of total dissolved gas supersaturation in the river at the given location. Gas percent is the daily mean of hourly observations. When gas pressure is exactly the same as the atmospheric pressure, the water is considered to be 100% saturated. If the gas pressure value is higher than atmospheric pressure, gas percent values rise above 100%. Daily averages are calculated from hourly values within the range of 90% to 200%. Gas percent data is often found to be quite noisy due to rapid fluctuations in spill volumes and atmospheric pressures. Dissolved Gas Percent is measured at Water Quality Monitoring stations in the forebay and tailrace of most projects (see Data Sites Map) and other key locations in the basin. Prior to 1995, the data are from a variety of sources within the U.S. Army Corps of Engineers.
Elevation: Elevation is given in feet above mean sea level and is a daily average of hourly measures. At most sites this will change less than a fraction of a foot over normal operations. Elevation is measured in the forebay of a project.
Elevation 10 Year Average: Daily average of elevation for a selected 10 year range. For each month and day, the data is summed for the selected 10 years and divided by the number of non-null data points available during that 10 year span.
Inflow: Inflow measurements represent the 24-hour average of hourly measures, reported by the U.S. Army Corps of Engineers. Inflow is given in kcfs, thousands of cubic feet per second.
Outflow: Outflow measurements represent the 24-hour average of hourly measures, reported by the U.S. Army Corps of Engineers. Outflow is given in kcfs, thousands of cubic feet per second. This represents the total outflow at any project, including spill and fish ladder flow.
Outflow 10 Year Average: Daily average of outflow for a selected 10 year range. For each month and day, the data is summed for the selected 10 years and divided by the number of non-null data points available during that 10 year span.
Spill: Spill also is given as a daily average of 24 hourly measures taken by the U.S. Army Corps of Engineers. It is also given in kcfs.
Spill 10 Year Average: Daily average of spill for a selected 10 year range. For each month and day, the data is summed for the selected 10 years and divided by the number of non-null data points available during that 10 year span.
Spill Percent: Spill Percent is calculated by DART from the daily averaged value for Spill divided by the daily averaged value for Outflow at a project.
Temperature (Scroll Case): Temperature (Scroll Case) is water temperature in degrees Celsius. This data is measured at the scroll case (part of the powerhouse) at a project. If provided values are in Fahrenheit, they are converted to Celsius. Temperature records are typically not collected outside the salmon migration season, so they are not usually 365 days long. Values above 0 C and below 35 C are averaged for a daily value.
Temperature (Scroll Case) 10 Year Average: Daily average of scroll case temperature for a selected 10 year range. For each month and day, the data is summed for the selected 10 years and divided by the number of non-null data points available during that 10 year span.
Temperature (WQM): Temperature (WQM) is water temperature in degrees Celsius. This data is measured at Water Quality Monitoring stations in the forebay and tailrace of most projects (see Data Sites Map) and other key locations in the basin. Temperature records are typically not collected outside the salmon migration season, so they are not usually 365 days long. Daily averages are calculated from hourly values above 0 C and below 35 C. Temperature at water quality monitoring stations was not collected prior to 1995.
Temperature (WQM) 10 Year Average: Daily average of water quality monitor temperature for a selected 10 year range. For each month and day, the data is summed for the selected 10 years and divided by the number of non-null data points available during that 10 year span.
Turbidity: Turbidity measures the water clarity, and by inference, the amount of particulate matter present. Turbidity is measured in the forebay or in the fish ladders of a project. Turbidity is reported in feet and measured with a Secchi Disk. In general, the Secchi disk is a 20 cm circular black and white plate. The Secchi disk is attached to a calibrated line and lowered into the water to the depth at which it disappears. The disk is then lifted until it reappears. The arithmetic mean of the two depths is considered the Secchi disk transparency or limit of visibility.