Lake Restoration and Aeration Case Studies

Effectiveness of Vertex Aeration to Eliminate Accumulated Sediment

Independent Study: East Twin Lake in Michigan has 2.4' muck reduction in only 36 months

"A community project removed over 90 dangerous timbers from the lake in 2002. In clearing the lake from these obstructions, discussion turned to the noticeable levels of sediment in East Twin Lake, primarily concentrated at its west side. Was this sediment a sawdust gift from our timbering forefathers that was stored on our sandy-bottomed lake? In 2002, we were determined to come to the aid of our upper mesotropic lake. We were not satisfied seeing our lake filled with unsightly and increasing sediment.

East Twin is a relatively shallow lake. Depths range four to eight feet, with some areas no deeper than about 26 feet. The lake bottom is primarily a hard sandy surface. During a period of low water levels, the high sediment level at the western end of our lake became more prominent. The sediment occupied as much as six of the eight feet of depth in many locations. These levels were unacceptable to boaters, water enthusiasts, and fishing aficionados. Our problem area is located at the western end of our lake. This area consists of 160 acres of surface area. An existing island on our lake and a sand bar, which traverses from the island to the northern shoreline, roughly contains it.

How could we rid our lake of this unacceptable sediment? In July 2004, eight Vertex Air3 XL4 Systems were installed throughout the cove at the west end of the lake. " - Twin Lakes POA

The Results

Muck reduced 55%, oxygen levels restored and excessive BOD eliminated.
 

Improved Oxygen, Water Clarity and Nutrient Levels

Heron Cay, a high-end gated residential development, was experiencing a number of problems in their 21-acre lake which is central to the community.

With maximum water depths over 20’, stratification caused severely low oxygen levels at the bottom. Having no beneficial bacteria to break down organics, heavy muck accumulation and foul odors from hydrogen sulfide gases were present. The lake was consuming what little available oxygen there was faster than it could be replenished, and excessive nutrient levels from fertilizer runoff only made conditions worse. The lake’s Biochemical Oxygen Demand (BOD) was extremely high.
 

The Results

After the design and installation of a Vertex aeration system consisting of 11 diffuser stations being fed by compressors totaling only 2-1/4 horsepower, Heron Cay was set up on a monitoring schedule to determine how lake dynamics were being affected. The results over the 4 month monitoring period were dramatic. Within days of initial start-up, the systems six main objectives were beginning to be realized:

• The breakdown of temperature and oxygen stratification
• Increased oxygen levels occurred throughout the entire water column
• Decreased Biochemical Oxygen Demand (BOD) to below detection levels
• Water clarity increased by 100%, from 3’ to 6’
• Excessive nutrient levels decreased; nitrogen down 80%, phosphorus down 59%
• Heron Cay’s lakes are returning to natural, healthy conditions.

"I've never seen the lake look better"- Mark Sanderson, President, Heron Cay HOA

Phosphate and Ammonia Reduction- Amanda Quillen, Ph.D.

Winston Park is a residential community in Coconut Creek, Florida. Winston Park Lake is 12.7 acres (5 hectares) and has a maximum depth of 32’ with an average depth of 19.5’.

The lake experienced massive fish kills every fall due to a reduction in oxygen during fall turnover, so Vertex installed an aeration system consisting of six XL5™ AirStations powered by 3 Brookwood™ compressors totaling 2.25 hp; which produced 14 CFM of air at 19 PSI. This system is sized to turn the water over in the lake at a rate of 0.8 turnovers per day.

The Results

Nutrients: The highest orthophosphate levels were observed at the sediment-water interface. These levels were reduced from 0.34 mg/L on July 15, 2009 to 0.01 mg/L on April 7, 2010, a 97% decline. Ammonia levels were also highest in the bottom waters, and were reduced 55% from 0.60 mg/L in July to 0.27 in April. Biological oxygen demand (BOD) improved steadily, decreasing to the background detection limit (2 mg/L) by October 23, 2009. This represents a 60% decline in BOD.

Oxygen transfer: On the morning of June 24, the day after the aerators were turned on full-time, oxygen concentrations averaged only 0.7 mg/L (225 kg of oxygen in the entire lake), with surface values topping out at only 1.75 mg/L. Near complete destratification of temperature was achieved by July 8, after 2 weeks of running the aerators fulltime.

Aquatic Midge Fly Swarming Controlled with Vertex Aeration

90% Reduction in just 16 months without pesticides

Hibbs Grove located in Cooper City, Florida was experiencing an ongoing outbreak of swarming non-biting midge flies (Order: Diptera, Family: Chironomidae) from their 6.5 acre lake. This nuisance prevented residents from enjoying their lakefront property. Sampling indicated an extreme infestation of midge larvae averaging 6,794 larvae/m², more than six times the recognized 1,000/m2 nuisance level.

Hibbs Grove turned to the biologists at Vertex Water Features for an environmentally safe solution. Vertex installed a CoActive Air 5 aeration system that provided compressed air to five XL2™ CoActive AirStations placed at the deepest points throughout the lake, effectively circulating the entire water column 0.76 times per day.

The Results

Oxygen levels increased immediately and accumulated organic muck on the bottom began to decompose thereby eliminating the habitat and food source that the midge larvae depended on. The improving water quality allowed predators of the midge fly, such as bluegill and aquatic insects to prey on the midges. The resulting increased predation, decreased nutrients and habitat competition contributed to a significant decrease in midge fly numbers.

Within 16 months of the Vertex system installation, the midge fly larvae population had been reduced by 90 percent, from 6,794 larvae/m2 to just 660 larvae/m2. Throughout the 16 months, there had been a visible increase in fish, dragonflies and water beetles all of which are natural predators of the midge fly larvae. With continued aeration, the oxygen levels have remained elevated and continue to oxidize bottom muck and suppress the midge fly population.