Truesdale Lake  

South Salem, New York

Lake Drawdown Has Begun for 2019

The Summer boards have been removed from the dam.

Our lake manager Pond & Lake Connection (P&LC) has installed the siphon tubes that will draw the lake level down another 2-3 feet to expose the lake bed over the winter.

[Read about what drawdown is and why this is being done here.]

As detailed in our drawdown meeting in June, our neighbors Scot Evans, resident math whiz Harold Ossher, and our lake manager liaison Lara Gorton have done an unbelievable amount of work to evaluate the water flow and re-design the siphon design to drawdown the water level this fall. See the detailed schematic below. 

Detail of siphon materials and mechanics

For testing, the original 6″ pipe siphon was reinstalled to use for water flow testing and has been in use over the summer. P&LC has installed two new 12″ pipes to have the drawdown complete by Nov 15.

The drawdown will end Feb 1, 2020 and the lake level will be allowed to rise after then. All dates are approximate as all work is weather (rainfall, snow, drought) dependent. 

IMPORTANT: NO FISHING WITHIN 15 FEET OF THE SPILLWAY WHILE THE SIPHONS ARE ACTIVE! The fishing line and hooks get tangled on the pipes and hardware and create a dangerous rusty hazard for lake volunteers and P&LC workers doing observation and maintenance on the site.

The siphons will be drawing water at 1000 cubic feet per minute. There will be warning signs posted at the dam. 

If all goes as planned, the water level will be 2-3 feet lower than the top of the dam spillway and will expose several feet of lakebed.

With cold weather, frost and freezing, the silt in the exposed shallow areas will compact and weed growth will be minimized. 

We will continue to report on the progress as the siphoning proceeds.

Full cross-section of siphon assembly.
Spreadsheet of water flow analysis for drawdown effort. Inputs are highlighted in blue, estimates are highlighted in red, and outputs are highlighted in green.

Updates through 2019 and early 2020:

Scot authored most updates and Harold, Lara, Rob, and James contributed with notes and comments.

Below is a chronological scientific update of the experience of the drawdown physically, mathematically, photographically, and mentally.

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