Flood events in the BSL area are volume-related as opposed to peak flow. It takes several days or more of rainfall to produce flood conditions in BSL. Because of this, and the length of time it takes rain in the upper reaches of the watershed to reach BSL (for perspective it takes about one day for flows at Michigan Bar to reach Benson's Ferry), there is some time to assess conditions before flooding in Point Pleasant occurs. Residents can monitor rain and stream gauges on the internet for both real-time and forecasted conditions.
Flood elevations at Benson's Ferry reached 18.3 feet in 1986 and 18.7 feet in 1997 (vertical datum NGVD 1929). Water surface elevations for Benson's Ferry are now given in the NAVD 1988 vertical datum which is 2.3 feet higher than NGVD 1929 in this area, and the table below reflects the datum change. The relationship of Benson's Ferry elevations to Point Pleasant flooding isn't direct (flooding in Point Pleasant was actually worse in 1986) because it depends on the storm type and levee failures. However, the Benson's Ferry gauge is the best tool to warn residents of pending flood status because it has five days of forecasted flood elevations. When elevations exceed the top of levee of McCormack Williamson Tract, levee failure is probable and substantial waters flowing north and overtopping Lambert Road would most likely occur. At this elevation levee failure of the WPRR just east of Point Pleasant is also possible. The following table shows various flood elevations at Benson's Ferry, how it relates to the area, and the impacts and/or actions to be taken including a flood warning that is distributed through an automated public notification system.
Forecasted Benson's Ferry Elevation [ft*]
Flood status
Automated public notification
17
Monitor stage for Point Pleasant
Residents should begin monitoring website
19.6
Flood waters reach low point in top of McCormack Williamson Tract levee east side
Failure of McCormack Williamson Tract levee possible
20.0
Levee failure imminent at McCormack Williamson Tract. Flows probably flowing north overtopping Lambert Road
Automated telephone message sent to residents. Possible flooding in Point Pleasant. Residents should consider evacuation.
20.6
High water in 1986
Point Pleasant flooded to elevation 14.0 NGVD29 (16.3 feet NAVD88)
21.0
High water in 1997
Point Pleasant flooded to elevation 11.8 NGVD29 (14.1 feet NAVD88)
* feet in NAVD88 datum
The Michigan Bar stream gauge can also serve as a warning tool since it has a five-day forecast, and it takes an additional day to reach Benson's Ferry. The gauge recorded a high water elevation of 18.3 feet in 1997 (this datum is relative to 0.0 at the bottom of the gauge inlet pipe) so anything approaching this could give Point Pleasant residents additional warning time. However the relationship of Michigan Bar elevations to Point Pleasant flood elevations is less reliable than Bensons Ferry so was not used in public notification.
Key gauges are shown in the following location map and tables listing both real-time and forecasted stream levels.
