Water temperature for the summer of 1996. In the graph below,
river water temperature for the Northfield, MA area is plotted
for the 150 day dive season (June 1 through November 1).
Graph - Water temperature in Fahrenheit:
The river is a well mixed system, there is no thermocline. Thus water temperatures are relatively constant at most depths. Two patterns emerge with regard to temperature, during the summer (June 1 through early September) water temperature slowly rises. In the first 100 days a 10 degree rise occurred (65 degrees to 75 degrees). This is in contrast to the rapid heat loss in the fall. In the 50 days from September to November, a drop of 30 degrees was recorded (75 degrees to 45 degrees). During this period the river bottom changed dramatically, all of the aquatic plants disappeared, having died back to their root systems beneath the sediment. This is the time to hunt for artifacts as the river bottom is bare -- but wear a dry suit!