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.
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 – approximate dates as all work is weather 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.
July 29, 2019
by rob Comments Off on Shoreline Maintenance Musings and other Lake Topics
In conversation and comments from around the lake, the weeds and algae are common topics — especially in the summer. One thing to remember is: We live on a lake, not next to a pool. The lake supports a multitude of animal and plant life. It is all interconnected and interdependent. And we have a large impact on it.
Many of the actions we take directly impact the health of the lake. For example, lawns leading right up to the lake shore encourage geese to land here and nest. Geese that are born and fledged here will return. Geese prefer an unimpeded path from their favorite food: Kentucky Ryegrass (aka lawn) and their water escape route. If you need a perfectly manicured lawn, consider planting a shoreline buffer of wildflowers and tall grasses. This will discourage geese from making your lawn their recreation area. And it will encourage beneficial insects and help native species.
Another area we affect the lake ecosystem is when we treat the lake to cut down on the plant and algae growth. As an extreme example: If we treated the lake to eliminate all plant life, it would kill all of the animals that rely on the plants for food. Then as the water heats up, we would suffer through blooms of toxic blue-green algae. That is definitely on our list of “no thanks.”
In our treatment plan, now managed by The Pond and Lake Connection, we are mainly looking to control the shoreline plants and algae growth that interfere most with the recreational value of the lake. This means we leave the middle of the lake alone since having plants in the water helps the fish, keeps the dissolved oxygen levels high, and can help prevent single celled blue-green algae — which thrive in low-oxygen conditions — from taking over the lake water in the dog days of August.
Our herbicide treatments are usually in the late spring just before Memorial Day weekend in May and once or twice in the early summer as needed. Algae treatments start in late July and can go into August. We are not allowed to treat the lake if dissolved oxygen levels fall to very low levels. This sometimes happens in the late summer and if it occurs, we have to wait for the water to cool down to treat the lake.
We strive for balance, but sometimes nature has other ideas. Plants and algae grow in the lake because that’s what plants do. They have 14 hours of sunlight each day during the summer to fuel them. For the shoreline variety, have to think about them like your lawn. If you don’t mow your lawn it will overgrow and you will not be able to walk through it. The same is true for your “water lawn” – no maintenance and the area around and beyond your dock grows wild. Some people like it that way, others want a clear waterfront. Others simply want a path to swim or boat out from their shoreline. Your needs dictate the extent of the action you personally take.
We have found if you want to control the plant growth around your waterfront or dock, the best and most effective way to control it is hand harvesting or cutting – then removing the plants from the water to dry and then compost. This can be time consuming and labor intensive, but the results typically last 4-6 weeks (sometimes as little as 1 week during peak season). The more you maintain, the easier it becomes over time.
(Note: If you would like more information about tools designed to make harvesting weeds and algae easier, check this page.)
Pond & Lake Connection will treat the lake for weeds and algae as needed on Tuesday July 23rd.
We use Clipper for weeds (clipperherbicide.com/) and Se-Clear for algae (www.sepro.com/aquatics/seclear). There is a 24hr restriction for irrigation with Clipper but no other usage restrictions for either chemical.
The floating algae clumps in the lake at this time are helping to absorb nutrients and keeping the water column clean. It is called filamentous algae and while alive, green and spongy, they are host to a number of different beneficial organisms for the lake ecosystem.
The algae treatment will kill some of the floating algae. The treated/dead algae will float into the coves, turn black and sticky, and decompose there if there is not enough current to move it downstream.
Additional chemical treatments will not reduce the volume of algae in the coves – it will actually worsen the situation and create more dead algae accumulation.
You can collect and remove it from your area or create current to move it downstream to help resolve the accumulation.
Several riparian homeowners have installed aqua-thruster water circulators along their shorelines to create current and help clear out accumulation. Please contact me if you are interested in more information about installing a circulator or if there are any other conditions in the lake that need special attention.
Thanks – Lara.
June 27, 2019
by rob Comments Off on Lake Treatment Set for Today June 27, 2019
A number of residents have been actively oiling goose eggs on the islands of Lake Truesdale since 2008 to control the population of Resident Canada Geeseon the lake. But the existing crew of people trained to oil eggs it has shrunk over the years — and we need more people to step up.
If you are interested in helping out, please contact us via email at lake@truesdalelake.com or via our Contact Form. The process is not too difficult and training is easy. The oiling season for 2019 is over, so it would be training for the 2020 spring season.
The physical intervention is the actual oiling of the eggs after mating has occurred but before the eggs have developed embryos. In our lake this typically takes place in late March or early April and can be pinpointed by observing the mating ritual of the local geese couples and finding their island nests about a week later.
Oiling works best with a crew of three working together. One person finds the nests, one person keeps the geese away from the nest, and one person oils the eggs. Oiled eggs are marked with sharpies to keep track of which ones have been treated. Records are kept for nests and eggs in each nest as a requirement of permission from the NYS DEC.
The behavior change for the geese is the most important long term consequence of oiling the eggs. We oil the eggs rather than simply break them because if the eggs are broken the goose simply lays more eggs. However, if the eggs are oiled, the development of the egg is stopped by preventing oxygen flow into the egg. This prevents the development of the embryo. Since the geese do not know this, they sit on the eggs for the 5-6 weeks it takes for hatching. When the oiled eggs do not hatch, the geese view it as a “failed nesting.”
Resident Geese bad, Migratory Geese good
In a successful nesting, the adults shed their flight feathers and take up residence with their new goslings on the lake, which is not what we want. In addition, other members of the flock who may have had failed nestings stick around to support the new parents in the flock.
In a failed nesting, they keep their flight feathers, take off, and head further south for the summer. They do not have the time to lay more eggs and have the goslings fledge and fly before the end of the season. This is what we want. These geese also do not develop a preference for returning to Lake Truesdale next summer and resume being Migratory Canada Geese rather than Resident Canada Geese.
Keeping the geese migratory means the problem is reduced both in the current year and in subsequent years. But other geese will take up residence on Truesdale if we stop oiling the eggs, so we must keep up the program to head off more future residents. We will also always have transient migratory geese — you can tell these geese since they are willing and able to fly away and visit other lakes since they do not have goslings to protect.
Oiling Results
In the last several spring hatching seasons, the crew of egg oilers has oiled over 100 eggs between the three islands each year. This has prevented the hatching of those eggs and has broken the resident behavior of those goose parents. To be successful, there has to be an initial oiling treatment and a follow up oiling treatment. Timing is the key to successful outcomes.
Egg oiling has made a huge difference in controlling the resident goose population on Lake Truesdale. When we first moved here in 1999, we would arrive home to 60-80 geese/goslings on our lawn. And easily double or triple that number on the lake. Lawns were covered in goose droppings. The beaches were favorite spots for goose gatherings. I have photos (deep in the archive) that I can dig up in case you think I am egg-agerating.
We have gotten it much more under control relative to those days — but we can always do better. Will you step up to help?
May 14, 2019
by rob Comments Off on First Lake Treatment Set for Friday, May 17, 2019
Back by popular demand! This year’s regional New York State Federation of Lake Association (NYSFOLA) Lower Hudson Lakes meeting will be on Friday, June 14, at the Sedgewood Club on the shores of China Pond in Carmel. Thanks to Dora and Scott Keller, who arranged for us to use this venue. The meeting will start at 9:30 am and conclude around 2 pm. A light lunch will be provided. The cost to attend is $5 per person.
We have a great line up of speakers. Maureen Galway-Perotti, a Master Gardener from the Putnam County Cornell Cooperative, will speak about shoreline buffers. Steve Di Lonardo of Aquatic Ecosystems Consulting will share his insights on nuisance algae. Kevin Fitzpatrick, the Director of Engineering from the East of Hudson Watershed Corporation, will talk about stormwater management and how that can protect your lake. One speaker from the past, Ken Belfer, will revisit to give a brief overview of the DEC pilot project at Mohegan Lake. And we will be treated to a display of aquatic plants and a talk on aquatic plant control by AJ Reyes of Northeast Aquatic Research. You will also have time for networking with other lake enthusiasts.
NYSFOLA regional announcement
If you are planning to attend, please let them know by May 31. Your reservation helps them ensure enough seating and food. Reserve your spot using this link: https://forms.gle/8rnjM6HWM3pMn6BM8
April 13, 2019
by rob Comments Off on June 13, 2019 – Lakewide meeting – Drawdown Initial Results & 2019 Plan
On Thursday, June 13 starting at 8:15pm at the South Salem Presbyterian Church, we will be holding a meeting open to all lake association and lakefront owners about the drawdown of Lake Truesdale.
The Pond and Lake Connection (the company that has managed Truesdale Lake weed and algae control for the past two years) attempted to draw down Truesdale Lake in the Fall of 2018 but they ran into technical, material, and weather difficulties that ultimately doomed the project for this past winter.
The unusually wet summer and fall of 2018 pushed the initial siphon pipe installation back several weeks from the original plan of mid-October. Once the siphon pipes were in, we received several very significant rainfalls that ended up filling the lake up faster than the pipes were able to drain it. The storms also disconnected the siphon pipes and interrupted the drawdown on several occasions.
2018 was a learning experience for us and Pond & Lake Connection and we will be doing an analysis of what went wrong and how to correct and account for it.
Some of the factors that need to be taken into account to correctly model the inflow to Truesdale Lake include:
acreage of lake (known: 83 acres)
watershed of lake (known: 2,380 acres)
average annual rainfall (known: ~48 inches)
soil absorption rate (known: 45%)
water inflow: 1.6 billion gallons/year or 4 million gallons/day (calculated from above)
When the lake is at a higher level over the spillway, it drains faster. Every inch it goes higher increases the rate of outflow. The reverse is true as well.
Once the water level goes below the spillway height, the lake ceases to drain. The aim of the drawdown is to get the lake to a point 2-3 feet lower than the spillway height. How is this accomplished? Siphon pipes are what we are using.
To model the outflow in this situation, we need to know:
diameter of the pipe (6″ used in 2018, recommend 12″ pipe for 2019)
number of pipes used (4 used in 2018, 6-8 recommended in 2019)
speed of water flow
length of pipe
12″ pipe is significantly more expensive than 6″ pipe
length of pipe impacts ability to siphon effectively
need more siphons and longer lengths of pipe
There are a number of other factors that impact flow rate that we will discuss. Using these, we can calculate estimated volume of flow over the spillway through the pipes. To be effective at lowering the lake level, this volume must be higher than the inflow rates. Complicating the real world results, the inflow rates can and do change on a daily basis due to rainfall and runoff.
Assuming we can get a volume of water out of the lake significantly exceeding the actual inflow into the lake, we will be able to achieve a drawdown. Once this has been achieved the questions that remain are:
how many days do we drain for to get to desired drawdown height
how long do the siphons stay in place for optimal drawdown impact
soil compaction,
freezing weed roots and seeds,
time to work on exposed waterfront {permits may be required!},
…etc
how long will the lake take to re-fill up to spillway height for spring
The meeting in June will be a chance for Pond & Lake Connection — along with the volunteers who are helping with the project — a chance to speak and answer questions about these calculations and plans for the upcoming season.
I write a bi-weekly column in the Record-Review (http://record-review.com) called “Talk of The Town” about current events in Lewisboro. Occasionally I will also write an article and submit photos about various topics and events in town.
A few weeks ago (Oct 19 edition) I wrote about the Truesdale Lake drawdown.
I encourage anyone who is interested in local news to subscribe to this paper which publishes every Friday and is only available in print form. The more Lewisboro subscribers the more they cover in town. The Record Review is the “Newspaper of Record” for the Town of Lewisboro. This means they publish all of the town’s meeting and legal notices as required by NY State law. And they cover Town Board meetings, Planning Board Meetings, Zoning Board meetings, and School Board meetings.
I have attached the drawdown article – and the top half of my Talk of The Town article – to this post (see below). A bunch has happened since then with the drawdown – check the Nextdoor Truesdale site for updates and comments.
(Photos by and ©Rob Cummings, more from the same kayak trip available here: 