Streamflow trends over the past year at Sangamon River At Rt 48 At Decatur in an interactive calendar format. View seasonal patterns on the river and see how an evolving climate has affecting streamflow levels over the past year. Click on any day to see what the streamflow was for that day, or sign up for a free account to view data for the past 111,469 days. The streamflow average over the past 10 days was 917.0 ^cfs, with a day to day variation of about 459.0^cfs.