Rivers are the main source of water supply for Montana's agriculture. Rivers are fed by snowmelt, overland runoff from precipitation excess, and groundwater systems and are therefore very sensitive to fluctuations in these inputs. When observed in the context of historical conditions, current streamflows can provide us with a first assessment of the state of the water supply.
The United States Geological Survey maintains, processes, stores and distributes free of charge streamflow data for thousands of sites over the United States. This information provides a basis to monitor America's rivers, and make informed decisions to improve public safety, Streamflow information is used for managing and forecasting floods, detecting trends in water flows at different time scales, plan infrastructure development, schedule power production, apportioning water resources for different uses including agriculture, and to conduct scientific studies, among other uses.
This map shows daily streamflow (red pins) and snowpack conditions (blue pins) in Montana. Clicking on a pin displays a plot of the current year's daily streamflow (red line) or snowpack (blue line). To provide a context and permit a qualitative assessment of the state of the water supply, streamflows and snowpacks for all available years are also plotted (gray lines).