2024 report and summaries
As part of the 2024 plan, the TLWQC was tasked with working as a team and with various contractors. EverBlue is a lake management company that completed a number of assessments and summaries, while Northern Lights, an aquatic weed harvesting company, provided a mechanical harvester to remove curly leaf pondweed from the Little Lake. The following provides a summary of the 2024 activities completed on behalf of the Twin Lakes communities by the TLWQC, at times with the help of these contractors.
Curly Leaf PondWeed Harvesting
The most high-profile activity that garnered attention in 2024 was the removal of the invasive aquatic vegetation known as Curly Leaf Pond Weed (CLPW). More information on CLPW and how it negatively affect lake quality is summarized below. CLPW is an invasive aquatic plant that was first noticed by Ed Nikles while paddling around the eastern shoreline of the Little Lake in 2021. At the time, it was not identified as an invasive species, but more of a curiosity. The vegetation slowly spread throughout much of the shoreline of Little Twin Lake until 2023, when it was identified as an invasive plant by an earlier version of the TLWQC. At that time, it was decided that steps should be taken to address CLPW and generally gain a better understanding of the water quality and characteristics of the Twin Lakes watershed.
A number of different approaches were evaluated to address the spreading of CLPW in 2023 and early 2024, including manual and mechanical harvesting, introduction of sterile grass carp, and the application of herbicides. Following extensive evaluation, consultation with various professionals and multiple group meetings that involved representatives from around the entire Twin Lakes area, it was decided that the best approach for 2024 was to perform manual removal and mechanical harvesting of the CLPW.
Initially, we aimed at completing a pilot study that consisted of removing about five of the twelve acres with CLPW along the Little Lake shoreline within 4 days and a budget of $7,000. However, we managed to employ a cost-effective mechanical harvester that cleared roughly seven acres in just two days, costing $3,400, well under the anticipated budget. The remaining areas with CLPW were not accessible to the mechanical harvester because of the many large rocks that protruded at irregular elevations from the lake bottom.
To address the remaining five acres, the lake communities joined forces on multiple volunteer days to clear CLPW by hand. This manual harvesting not only effectively removed the weed but also served as a wonderful event to bring folks together. In all, we harvested the equivalent of eight pickup truckloads of CLPW, which is impressive, considering its small volume once out of the water.
We were able to use the vegetation survey from EverBlue (discussed below) to create a baseline condition before any harvesting and another one after the mechanical and manual harvesting were completed, as shown below in the side-by-side images:
As shown, a small amount of CLPW was left behind near the Preserve Beach where it was intertwined with lily pads, and in rocky areas along the eastern shore, where mechanical harvesting is impossible and hand harvesting very difficult. Nevertheless, we managed to clear approximately 95% of the CLPW from Little Twin. Together, we achieved much more than originally planned, which is a testament to the community coming together over several weekend afternoons to remove this invasive species. On another note, it was encouraging to see that water shield—a type of small, oval-shaped lily pad vegetation was able to grow in areas previously dominated by CLPW, showing that non-invasive plants can compete with CLPW.
EverBlue 2024 Scope
One of the primary efforts for 2024 was the hiring of a professional lake manager and the collection of a significant amount of information to better assess the health of Twin Lakes. The following includes a list of field activities contracted to EverBlue in 2024:
Aquatic Vegetation Surveys
Vegetation Survey, Bathymetric Survey, and Bottom Hardness Survey
Sediment Sampling Testing and Analysis
Muck Reduction Pilot Study
Watershed Assessment (Separate summary available: click here)
The results of these assessments were presented in EverBlue’s Summary Report and are summarized by the TLWQC in the sections below.
Aquatic Vegetation Surveys
As noted in the previous section, the EverBlue team surveyed both the Big and Little Lakes before and after the manual/mechanical harvesting of CLPW took place. As indicated by the maps below, these harvesting events were extremely successful in the short term, but we will be completing a similar survey in May (of 2025) to gauge any long-term effects. Although we know it will grow back from the seed bank that is present in the lake sediments, we are eager to see if there are changes in the growth pattern.
In addition to a focus on CLPW in the Little Lake as shown above, EverBlue conducted a survey of other common aquatic plants such as lily pads and water shield, which are present in large patches in the Big Lake. During this vegetation survey, EverBlue identified bladderwort in the northeast area of the Big Lake that was then also found by the TLWQC team in the northwest portion of Big Lake, near the outlet. Samples of the bladderwort were sent to our professional partners at PLEON, who confirmed that it was not an invasive species but this will be something that we continue to monitor.
Bathymetric Survey, Vegetation Scan, and Bottom Hardness Survey
EverBlue conducted and produced scans for the presence of general vegetation, a bathymetric survey (i.e. a contour map of the lake bottom), and a bottom hardness survey to help identify areas where excess muck may be accumulating.
Bathymetric Survey Results:
The bathymetric survey simulates the contours of the lake bottom and provides a guide for where there are shallow (lighter colors) and deep areas (darker blue).
Back in 2001, the lake water quality team actually created very similar maps of the two lakes, but rather than using fancy sensing equipment, they did the work by hand (thanks to Peter Loewrigkeit and others).
We were able to overlay the 2001 survey (black lines) and the 2024 survey (red lines). Since the original data set was done by hand, one would expect some variation to the more recent scan, but they match well. This shows that very little has changed over the last ~20 years and results in some very important observations:
The lake bottoms have changed very little over time and assuming no significant change in the overall lake level, there appears to be no significant areas of sedimentation.
In some aquatic environments, muck thickness increases by multiple feet over a few years, but over ~20 years, we’ve seen either no or minimal increased sedimentation.
There is no indication of significant scouring or increased sedimentation in any of the areas of known stormwater inputs.
There is some increased sedimentation downgradient of the Twin Lakes Creek outlet. This makes sense since this creek is one of the largest inputs into the lakes, so you could expect that the sediment that is carried with the surface water settles out downstream into the Big Lake.
Vegetation Scan Results:
The vegetation scan is fairly qualitative and merely provides a snapshot of the relative abundance of vegetative material, including curly leaf pond weed, lily pads, and water shield. The survey aligns fairly well with what you can see from boating around the lakes (green areas indicate the presence of vegetation; yellow and red areas show increased vegetation density).
Bottom Hardness Scan Results:
The bottom hardness scan is also fairly qualitative and provides indications on where the lake bottom is soft/“mucky”(light orange) or hard/rocky (dark orange). This generally aligns with anecdotal knowledge of the lake bottom.
Sediment Sampling Testing and Muck Reduction Pilot Study
EverBlue collected sediment samples throughout both lakes and analyzed for percent organics in the sample, as well as the amount of total phosphorous, a common nutrient used to track relative lake health. In August and September, muck reduction pellets were introduced in certain areas of both lakes as a pilot study. The muck reduction pellets are a highly active, concentrated blend of natural enzymes and pond bacteria. Bacteria will naturally “eat” or breakdown the organic rich muck that is present in the lake bottom. This soft sediment or muck is the result of the accumulation of animal waste, dying vegetation, and leaves. Every year, the leaves fall off the tree, the lily pads/water shield die off and sink, and plenty of animal poop settles to the bottom, all of which eventually adds to creating muck. The bacteria breaks this down as a natural process and the addition of these pellets is supposed to increase the rate of breakdown. Overall, the sediment sampling and muck pellet study resulted in the following observations:
There is an above “average” amount of organic matter and total phosphorus in the sediment from the two lakes, but this is a relative measure and does not by itself cause a reason for alarm.
The Little Lake has more muck accumulation, which is likely based on the fact that it does not have a direct outlet except to the Big Lake, and has a longer residence time – where the water does not cycle out very fast (~4 years), and is generally smaller.
The muck reduction pilot study had mixed results, where some reduction in organic matter was identified, but it was not consistent.
While the EverBlue Report identifies overall success of the muck pilot study, the results are fairly uneven and, based on TWQC’s review, are not conclusive. That being said, there is a good amount of interest in the application of muck reduction pellets and the TLWQC will be looking to provide options for lakefront owners in 2025.
