DART Hourly Water Quality Metadata & Glossary

Data Locations

Hourly Water Quality Glossary

Barometric Pressure (BaroPr)

Barometric Pressure is atmospheric pressure as measured by the U.S. Army Corps of Engineers water quality monitoring site, given in mmHg.

Dissolved Gas (DisGas)

Dissolved gas is a measure of the pressure of dissolved gas in the water column as measured by the U.S. Army Corps of Engineers water quality monitoring site, given in mmHg. 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. Often collected at irregular intervals, this parameter may be missing values for one or more days, or reported values may be obviously incorrect. Daily averages are calculated from hourly values between 600 and 900 mmHg. Hourly values are reported as received from the USACE.

Dissolved Gas Percent (DisGasP)

Gas percent reflects the degree of total dissolved gas supersaturation in the river at the given location. 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%. Hourly measures are the derived value of (Dissolved Gas)/(Barometric Pressure) as reported by the USACE. Gas percent data is often quite variable due to rapid fluctuations in spill volumes and atmospheric pressures, as well as sensor errors.

Outflow

Outflow measurements represent the hourly measures reported by the U.S. Army Corps of Engineers at a project. 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.

Spill

Spill measurements represent the hourly measures reported by the U.S. Army Corps of Engineers at a project. It is also given in kcfs, thousands of cubic feet per second.

Spill Percent (SpillP)

Spill Percent is calculated by DART from the hourly values for Spill divided by the hourly values for Outflow at a project. Spill percent is only available from the Composite Report.

Temperature (TempC)

Temperature is water temperature in degrees Celsius as measured by the U.S. Army Corps of Engineers water quality monitoring site. Hourly values are as reported by the USACE. Daily averages are calculated from hourly values above 0^oC and below 35^oC.

Additional Information

• Please refer to the DART River Environment Metadata & Glossary to view additional information about each location, including DART daily datasets inventory.
• Lower Columbia River Dissolved Gas Monitoring Network, USGS
• Map of Water Quality Monitoring Network, USACE
• Outflow and Spill data are collected at the project (dam). Barometric Pressure, Dissolved Gas, Dissolved Gas Percent, and Temperature (F) are measured at Water Quality Monitoring stations in the forebay and tailwater of most projects and other key locations in the basin.
• Current monitoring station details (including river mile and lat/lon coordinates) can be found on the Total Dissolved Gas (TDG) Monitoring Station Summary Data Sheet, USACE Columbia Basin Water Management Division.
• Operation dates vary by location and year.