Not sure what the DES is using for a temp probe, but mine is a Sensatronics E4 temp monitor which is brand new. If you're curious about its techie specs, you can visit
www.sensatronics.com and look at the E4. The company is located in Bow, and has a reputation of making very accurate instruments.
When I saw the differences in the readings I always figured it's because the state's probe measures the temp of the water going thru the dam in Lakeport at the end of Paugus Bay. Paugus Bay heats up more easily in summer and freezes sooner in winter than out here on the open lake. The lake gets stirred up a lot more out here.