by Scot Evans 

Winter drawdowns are designed to expose the lakebed to the air and sustained sub-freezing temperatures. Over the past five years, we have improved and fine-tuned our annually-tested lake drawdowns. Siphons to draw the lake down three feet below normal winter spillway level are necessary because the low level outlet under the dam is no longer functional. Our 230 foot long dam was completed in July 1908, so it 117 years old. Since the 1980s, the control tower has been flooded and the sluice gate control wheel submerged.

The Drawdown Team consists of John Gusmano, who approves and oversees each drawdown as the Chairman of the Lake Management Committee; Scot Evans, who designed the three drawdown siphons necessary to drain the lake approximately one foot every ten days, also monitors the progress of each drawdown, submitting weekly reports and siphon restart notifications; James Gorman of The Pond & Lake Connection, who builds the siphons and recommends modifications based on field performance; and Lucille Munz, who incorporates all siphon design improvements into AutoCAD (commercial computer-aided design) “blueprints” as shown below.

The air-exposed lakebed and sub-freezing temperatures allow the weed tubers buried in the silt and decomposed mud to freeze and die. The dry air also desiccates and compacts the silt to deepen the lake slightly without the expense of dredging. Some lakeside homeowners have been very helpful in raking out trash, decomposed algae mats, and cleaning their exposed lakebeds as shown in these before-and-after photos.

The summer photo below of the refilled lake captures the beneficial effect beautifully; it shows no weed growth in the area where the lakebed was exposed to air and sub-freezing temperatures, while dense weed growth is clearly visible beyond that point where the lakebed was still submerged.

A few shoreline residents have procured throwable weed rakes, attached to a nylon line, to haul in and compost lake weeds into natural fertilizer and “black gold” — decomposed soil to use for topsoil and gardening throughout the year. This is highly appreciated.

Howard Citron, a resident engineer with the TEA, will provide John Gusmano with dam-specializing-contractor estimates to repair the low level outlet so that we can eliminate the siphons and draw the lake down using the repaired sluice gate control wheel — currently submerged, shown below:

Silt infiltration from Ridgefield‘s West Mountain watershed into Pumping Station Swamp and the Boway Stream makes our lake shallower every year. The Siltration Pit, between the Boway Stream and the lake, has never been pumped-out, required since 1980, in order to prevent silt accumulation in the lake.

As a result, 45 years worth of silt has been allowed to flow freely into the lake. The TLPOA President will come up with a plan to remediate the lake of accumulated silt. The drone photo below shows some of the silt that has poured in from the over-loaded siltration pit.