U.SA geological survey. Here is the site for "water quality. It can be difficult to navigate unlesss your familiar with it. FRESHWATER TEMPERATURES
Category is water qaulity. On the upper right plug in the state. In the other boxes plug in water quality and pick table grouping such as major river basin or hydrological unit or by county. Press go. You will see a grouping of numbers to the right. including water temperatures ph . etc. Remember the temps are under "water Quality". The temperature is in Celcius but I have provided a conversion script on the conditions page (and many other pages as well). CELCIUS TO FAHRENHEIT CONVERSION
Plug in the celcius number in the box and click the other box. That will be your temp in fahrenheit.