24' - Disastrous Flooding.  Widespread flooding across upper Napa Valley with travel essentially impossible.  The peak water level during the flood of 12/31/2005 measured 23.6 feet.<br><br>22' - Major Flood Stage.  Major flooding throughout the upper Napa Valley with most roads inundated, making travel extremely difficult and unsafe.<br><br>20' - Moderate Flood Stage.  Moderate flooding of the lower portions of Silverado Trail along the reach.  Inundation of low lying residential areas along the east river bank in the vicinity of Pope Street Bridge.  Secondary and many primary roads inundated; most major cross roads inundated and unsafe to pass.<br><br>18' - Minor Flood Stage.  Minor flooding of low lying agricultural areas along river begins.  Low lying rural residential areas immediately adjacent to the river and some secondary roads affected.<br><br>16' - Monitor Stage.  WFO Monterey may issue a Flood Watch-based products to cover Napa Valley regional flood potential at this stage.<br><br>