Truesdale Lake  

South Salem, New York

Drawdown: Report 6

These are some of the email reports and communications from Scot Evans from Truesdale Lake, James Gorman from Pond & Lake Connection, and others involved with the project. Putting selected parts up here for all to see what some of the discussion and learning is looking like.

October 21, 2019

Rain from the strong nor’easter bombogenesis (at least 24 millibar drop within 24 hours) began at 2 pm Wednesday 10/16/19 and ended just after midnight where we received 3.34”of rain. On Thursday 10/17/19, we received a small amount of wrap-around moisture with an additional 0.04” or rain.

At the beginning of the storm, the lake gauge (LG) was 2.9 feet below the spillway deck where it had remained for the past seven days. Rob Cummings also took excellent video and still shots with his drone of the exposed lakebed at this drawdown target level before the storm arrived. Will send some of his choice photos later this week.

Lake Level Rising (LLR) occurred rapidly and rose 17 inches in the 40 hours during and after the storm. This is a multiplier of 5+ times the rainfall.

Keeping in mind that the lake contour is a cone, it would take some severe calculus to convert the rise to the vertical contour of a cylinder.

James Gorman with P&LC arrived early on Friday 10/18/19 and restarted one 12” siphon and the 6” siphon at 8:30 am, which began Lake Level Lowering (LLL) as the inflow from the storm steadily decreased.

Here are the readings taken at the beginning and end of the storm, then every four, eight or sixteen hours thereafter.

10/16      1400 LG -2.9 feet datum (before rain began and followed by 3.38” rainfall from the storm)

              2400   LG  -2.5 feet or LLR     4.8 inches (Immediate Rise)

10/17      0800   LG  -2.2 feet or LLR     8.4 inches

              1200    LG  -2.0 feet or LLR  10.8 inches

              1600    LG  -1.8 feet or LLR  13.2 inches

               2400   LG  -1.6 feet or LLR  15.6 inches

10/18       0800   LG  -1.5 feet or LLR  16.8 inches (Peak Rise &
siphons energized – flowing 617 CFM)

               2400   LG  -1.5 feet or LLR  16.8 inches (remains peak
as siphons match inflow)

10/19       0800   LG  -1.6 feet or LLL  15.6 inches

               2400   LG  -1.6 feet or LLL  15.6 inches

10/20       0800   LG  -1.7 feet or LLL  14.4 inches

               2400   LG  -1.8 feet or LLL  13.2 inches (received
0.33” rain from a weak offshore nor’easter)

10/21       0800   LG  -1.8 feet or LLL  13.2 inches

Thanks Scot! This tells me we won’t have a problem refilling the lake is the spring!


Good point, Rob! Meanwhile, it’s good to see the (reduced) siphons doing their job again. Thanks for the detailed measurements, Scot, it’s very helpful to have this tracking of what is happening.
– Harold

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