The sulfur smell from well water is common here due to the volcanic conditions of this area. It smells more intense with warmer water. The recent occurance is likely due to the water source pulling from a variance of the wellspring. This can be easily remedied with filtration.
If you need more info, feel free to email me directly :)
We have a company here that also has locations in Junction City - called EcoWater -
You might have your water tested - one really gross story - we had a toad get into our pump once and it caused a smell - then it got into the hot water heater in parts..... it was a real mess...
Broker, RE/MAX Equity Group Inc