The Low-Flow Calculator Tool is a web application that tells you how river flow might be affected by future climate change in your area.

The tools asks you to select a river of interest. The calculator then projects what the change in low flow will be for the selected river under projected future climates. The tool provides a summary of both the current and projected low flows for the river.

Low flow is a stream’s flow occurring when there is little or no precipitation. Low flow is used to calculate the allowable loads of many polluntants, such as microbial pathogens and some toxics. The allowable loads are calculated for a low flow period because during this time, dilution provided by the waterway is minimum and pollutant concentration in the water increases. The low flow used in this tool represents the annual minimum streamflow that is exceeded nine out of every ten years. By comparing the low flow predictions from this tool to current data, you can see how low flow changes in different future scenarios and determine if instream dilution will decrease in the future.