(KOH) – The National Weather Service is warning of MAJOR flooding along the Walker River, similar to the 1983 & 1986 snowmelts.  Major flooding is predicted from the Mason Valley downstream through Yerington to the Weber Reservoir.  The river is expected to reach flood stage of 9.8 ft by early afternoon on Monday, and keep rising to about 12.9 ft by early Thursday morning.  The weather service expects that flooding could last days or even weeks, with thousand acres of farmland and pasture flooded as well as some parts of Yerington. If the river breaches the Channel in Mason Valley, there will be much more significant impacts.  Lyon County and the City of Yerington are working with farmers and irrigation companies to pull as much water off of the river and into ditches to reduce flows. Residents are filling sandbags and being told to prepare for potential evacuation.