Whats up with the Water Level?

While responding to the volatile water level is not our Associations Charter, we realize that this is
a good forum to convey information we have received relative to this issue.

First, some facts about the Dam:

  • The Dam (Known as Kellys Falls Dam) is leased by and operated by Enel North America.

  • Enel NA also owns the property, and the building.  The State of NH owns the Dam itself.

  • The power generating unit which is below the dam, can flow through 350 cfs (cubic feet per
    second) of water.

  • The Dam has two overflow gates, each capable of allowing 50 cfs through.  

  • Therefore the dam can handle 450 cfs total.  Any amount over this, fills up the lake, then
    flows over the dam. (They could close the overflow gates, in which case any amount over
    350 cfs flows over the dam.

  • Enel NA can not generate at full capacity when the storm boards have been breached.  
    They have a financial interest in repairing them as soon as possible.

  • Whats todays flow?  Click here to find out (the lower blue line is flow):  NWS Forecast Stage

  • The Dam and the water level and flow is monitored electronically, but there is an Enel NA
    employee on site every day (365 days a year).

  • When the water level breaches the dam by 6 inches, the storm boards (plywood and steel
    pegs) are designed to bend, to allow extra water over the dam.  

So what causes the lake to lower?

  • First, the storm boards "trip".  This means that the lake level was high, and flowing over the dam.  Debris such
    as trees, tires, refrigerators, etc damaged (broke) the storm boards.  Sometimes only a few, sometimes 50 -
    75 feet worth.
  • Once the storm surges recedes, the lake reduces to the level below the boards (roughly 3-1/2 feet below
    normal).
  • But Enel NA can not repair the boards until the water flow falls below 400 cfs.  This because the overflow
    gates are above the main dam level, but within the storm board height. Therefore, they can only redirect the
    50 cfs each, when the lake is at full height.  
  • It often takes a few days or longer, for the lake level and lake flow to reach the point where they can repair
    the boards.

What effects the flow?

  • Simple answer - rain!  The more rain we get, the more water drains into the river system, the
    faster the flow.  

  • Enel NA does not hold any water back.  they allow the 350 csf to pass through their turbine,
    and the rest through the flood gates and/or over the top.  They have nothing to do with
    controlling the flow of the water.

So why has the level been so erratic the past few years?

  • Another simple and similar answer - the rain.  The weather patterns we have been getting
    since 2006, have been very different from the historical patterns.  Not only in the total
    amount of rain received, but when and how we receive it.  The feast or famine rain patterns
    greatly effect the flow of the lake.

  • There also seems to be more debris in the lake than in the past.  Perhaps due to the level
    changing so often, perhaps due to other reasons, but the bottom line is, there are more
    trees, barrels, chairs, and debris floating through the lake, many of which cause damage to
    the Dam.

So what do we do?

  • Besides praying for better weather, and taking responsibility for less debris in the lake,
    there is not much we can do.  Enel NA has presented a few costly plans to the State.  These
    plans would replace the storm board system with a more controllable system that would
    allow them to lower the boards during high water preventing damage, and raising them
    when all is clear.  The problem is that they (Enel NA) do not own the Dam, the State does,
    so the State would have to do it!

Flood flows:

By the way, the flow level during the 2006 flood exceeded 12,000 cfs!  Similar levels were
reached during the 2007 flood, whose chart I happened to save - check it out below. The flow is
the blue line that exceeded the chart capacity 12 hours before peeking!