Colorado River Basin Natural Flow and Salt Data
The information contained in the following web pages is of a technical nature. It is intended for use by those in the scientific and water resources communities interested in natural flow and salt computations in the Colorado River Basin. These data are furnished by the Bureau of Reclamation for use as hydrologic inputs to the Colorado River Simulation (CRSS) long-term planning and operations model. This is not a database of record. Physical modeling assumptions used to compute these data are updated to match the latest used in CRSS. The data are regularly recomputed from 1971 to present.
Natural flow data is termed 'CURRENT' when it is currently being used for modeling purposes in CRSS. Please note that even though natural flow data is termed 'CURRENT' it is SUBJECT TO CHANGE over the entire record due to source data updates.
Presently the consumptive uses and losses data from 2006-2019 used to compute natural flow are provisional and will be revised in the future. These revisions will change the natural flow computation.
Natural flow data is termed 'PROVISIONAL' when Reclamation provides an early estimate of natural flows at the Colorado River at Lees Ferry, AZ for water operators and stakeholders at this key gage location within the monitoring network. Estimates are published following the completion of the January, April and August 24 Months Studies. These provisional data are not used for modeling purposes in CRSS.
Natural Flow and Salt Data IndexCurrent Natural Flow and Salt Data
Natural Flow Supporting Data
Natural Salt Supporting Data
Previous Natural Flow and Salt Data
Provisional Natural Flow Data
Last Updated: 15NOV2022