What’s up with the Hoover water level?
We see the water level go up and down at Hoover, but many of us don’t know much about its normal cycles. You can see a chart like this one on the US Coast Guard website.
An analyst with the City of
Columbus has been good enough to send me daily water level readings at the end
of each month for the past several years and I have added that to a base of
data that I got several years ago from Jay Huling. I have data and graphs of the Hoover water
level going back to 1955 when the reservoir was first filled.
You can see from the chart that the water level over the past 3 months has gone from a low of just under 880’ to almost 891’. The normal full level is 894’. That’s not the depth anywhere, nor is it exactly the elevation above sea level. It is the elevation above NGVD 1929. NGVD (National Geodetic Vertical Datum) 1929 is a reference elevation that is roughly based on sea level. Establishing “sea level” is much more complex than we might think, but once the datum is established it is a consistent “zero” point for other measurements.
In a normal year, the Hoover water level may vary 10-12 feet throughout the year, starting at 894’ and dipping to 882’ or so by the end of October or November. In 2010 the water dropped to just below 876’ by mid-November. This came close to being a problem for docks-out that year. The end of the concrete ramp is such that if the water level reaches 876’ we can’t get the trailers we far enough into the water to load the dock sections.
Moving the docks in and out as the water level changes is something that the Docks Committee takes care of. When water level changes quickly or when an anchor chain breaks that make the task more difficult. Raft owners also deal with this, although since it is a shared responsibility often the rafts are left aground as the water level drops, sometimes damaging the barrels that keep the rafts afloat.
At the end of last season, the water level had dropped significantly and there was damage evident to a number of rafts at Docks-Out. Barrels were loose or damaged and leaking. The end of March will be here soon and time for Docks-In. Raft owners need to repair any damage to their rafts and have them ready to launch at Docks-In.