Lake Guard Treatment in a Semi Enclosed System




BlueGreen Water Technologies Ltd. was approached by ATS in late August 2020 to carry out a trial remediation plan in Utah Lake. This was carried out in a semi-enclosed marina that is subjected to sporadic cyanobacterial (blue-green algae) blooms. The BlueGreen team assessed the ecological situation in the marina and treated the area during the weekend of Labor Day 2020. A dense scum of the toxic cyanobacteria, primarily Anabaena sp., was identified and treated using Lake Guard® Blue. Monitoring in three locations, two within the marina and one outside, demonstrated successfully removal of the toxic cyanobacteria within a few hours following the treatment. Populations of heterotrophic bacteria and green algae, such as Chlamydomonas-like sp., was established in the marina within 24-66 hours after the treatment. This indicates that the treatment actively prevented the cyanobacteria’s recurrence in the marina despite the high inward water flux from the Lake.

This campaign was a minute in BlueGreen standards as only 10 acres were treated relative to the thousands of acres treated by us to date. Nevertheless, this was a unique project due to the massive influx of contaminated water feeding into the marina. Targeted treatment against toxic cyanobacteria causes an ecological succession of beneficial green-algae that developed in the marina capable of out competing cyanobacterial blooms thereby substantially delaying the occurrence of such blooms.   


Cyanobacterial blooms disrupt the aquatic ecosystems and reduce their bio-diversity. Under these conditions, cyanobacteria can change the biological composition and the chemical conditions in a waterbody (Harke et al. 2016; Huisman et al. 2018; Paerl 2018). They inhibit the growth of competing phytoplankton species usually by physical obstruction of direct access to sunlight, as well as by the secretion of an array of inhibiting secondary metabolites (Huisman et al. 2018; Dittmann et al. 2013; Neilan et al. 1999; Pearson et al. 2016; Harel et al. 2013; Schatz et al. 2000; Schatz et al. 2007).  By inhibiting the growth of various competing phytoplankton species, these allelochemicals help the toxic cyanobacteria become the dominant organisms in the water bodies. Some of these allelochemicals, also known as cyanotoxins, are also harmful to humans and animals (Huisman et al. 2018; Dittmann et al. 2013; Neilan et al. 1999). They may cause a range of health risks, from nausea and skin irritation to cancer, liver and neurocognitive diseases.

Moreover, an increasing number of recent publications show that the risk to human health may extend to nearby communities due to the airborne nature of the cyanotoxins (Sharma and Rai 2008; Wiśniewska et al. 2020; Murby and Haney 2016; Facciponte et al. 2018). These  harmful algal blooms have a devastating impact on the local economy: from tourism and recreational activities to the devaluation of property values around the contaminated Lakes. This latter point was emphasized in a study about the effects of harmful algal blooms on the economy of the Buckeye Lake area that lost an average of $100 Million in property value depreciation over six years (Wolf et al., 2017; Wolf & Klaiber, 2017).

The Lake Guard® Technology, an innovative targeted treatment against blue-green algae (USA Patents No. 10,729,138 and 10,092,005; USA Provisional Patent 2020,267,970A1), selectively eliminates and prevents toxic algal blooms in lakes, irrespective of size or shape. It is a proprietary new formulation of potent algaecides that allows the granular product to float on the water body slowly releasing the active ingredient on the water surface home-in on cyanobacterial aggregates as they drift in the water surface. The prolonged oxidative stress exerted by the Lake Guard® products triggers a biological process named programmed cell death signaling within the cyanobacterial population. This biological signaling cascade reaches naïve cyanobacterial cells found throughout the water column resulting in a population-wide collapse of the cyanobacterial community. The collapse of the cyanobacteria enables beneficial green algae re-establish their dominance in the lake, essentially re-setting the ecological conditions to the pre-toxic bloom’s era. The growing green algae population consumes essential nutrients (e.g., phosphorus and nitrogen) and thus reduces the cyanobacterial growth in the water body and improving the overall condition and health of the water body.

Fig. 1. A drone image from the north-east of Lindon Marina on September 4, 2020, at 6:00 pm. A constant flow of turbid water from Utah Lake is observed streaming into the marina. Red circles specify the measuring points in the marina (“A”), at the entrance (“B”) and outside the marina (“C”).

Treatment setup

Lindon Marina (Fig. 1), an 8 acres marina with an estimated depth of 3-6 ft, is located at the west corner of Lake Utah, Provo UT. At its eastern side it is open to Lake Utah (Fig 1). The marina serves mainly for recreation (boaters, fishing, and swimmers). It is subjected to a high occurrence of cyanobacterial blooms that drift and concentrate into the marina by daily eastern winds from the 380 km2 Utah lake (Fig. 2).

Fig. 2. True-color satellite image, left panel, shows high cyanobacterial intensity in Utah Lake on September 4, 2020. Processed image with the Lake Guard® View, right panel, depicts cyanobacterial intensity levels as a heatmap scaled from undetectable/low levels (cold colors, blue) to high levels (warm colors, red). An arrow points on Lindon Marina that hardly noticeable at this resolution.

Previous treatments to reduce these blooms in the marina used 400 gallons (equals to ~4000 lb) of the liquid copper-based product (~5% copper as ion). BlueGreen‘s treatment was achieved successfully with only 250 lb of Lake Guard® Blue (25.6% copper ion) that was released within <60 min in specific points in the marina.


Assessment and Rapid Response

The BlueGreen team arrived to survey Lindon Marina on Thursday, September 3, 2020, at ~18:00 (Fig. 1). A small patch of cyanobacterial bloom consisting of Anabaena sp. was spotted at the marina’s south-east corner. A strong drift of turbid water pushed into the marina from the Lake was observed (Fig. 1). By the morning of Friday, September 4, the marina was already covered with a cyanobacterial scum over the entire water surface. Due to logistical constraints, the Lake Guard® Blue arrived only at 17:00, and treatment was applied at ~18:00 (Fig. 3).

Results and discussion

The treatment took <60 min. using a rowboat (If a motorboat would have been used, the treatment time would have lasted 5-10 min). Due to the impressive exponential growth of the cyanobacteria in the marina (observed from 09:00 to 17:00, on September 4, 2020) – it was decided to apply 250 lb of Lake Guard® Blue. Treatment started at ~18:30, and by ~20:00, the scum that was concentrated at the east side of the marina (Fig. 4A) was dissolved entirely (Fig. 4B). The water looked clear half a day later, and no appearance of viable cyanobacterial scum was observed (Fig. 5).

Fig. 3. Drone footage of the Lindon Marina on September 4, 2020, @ ~18:00. The picture is facing east. (A) closeup treatment with Lake Guard Blue from over the boat, and (B) the lane that the floating particles of the product form on the water surface before dispersing with the wind and current
Fig. 4. Photographs taken before and after the treatment showing the same angle of the north-west corner of the marina (facing to the north), 2-hours apart at (A) 18:00 and (B) at 20:00. The difference in the background color was due to sunset. Some bluish particles originated from the Lake Guard Blue, can be observed on the water surface post-treatment.
Fig. 5. Photographs taken before and after the treatment showing the same angle of the northern side of the marina (pictures are facing south) on (A) September 4, 2020 at 18:00, before the treatment and (B) 15 hours later on September 5, 2020. Post-treatment, some green plants that grew below the water surface were not affected by the Lake Guard® Blue treatment – and could be seen once the water turbidity was improved.    

Three sampling points were selected representing the aquatic environment as specified in Fig. 1: sampling point A – the marina, point B – the entrance to the marina, point C – Utah Lake, as was represented by a single sampling point outside of the marina. At each point, 15-25 samples were registered using the YSI Sonde each time around 09:00 am at the same sequence (point A – then point B and C). The YSI Sonde registered the pH, dissolved oxygen (DO), chlorophyll-b, and phycocyanin (proxies for eukaryotic algal- and cyanobacterial- biomass, respectively). The chlorophyll-b to phycocyanin ratios determined from the same collection were hereby defined as Resistance Index (RI). The data were then analyzed using Two-Way Anova using Graph Pad Prism8 (Fig. 6).

Fig. 6. Two-way ANOVA analysis of (A) Resistance Index, showing the influence of the Lake Guard Blue treatment provided at time zero. (-7 is 7 hours before the treatment, the others shows the time in hours after the application). (B) Resistance Index as in (A) with statistical analysis. (C) DO and (D) pH. Add hours to the X axis in (A)

Clearly, while the resistance index (Figs. 6A and 6B) was identical in the three monitoring points, 7 hours before the treatment, it kept declining in the lake itself (due to the raising cyanobacteria population). In contrast, the RI increased significantly within the marina and, surprisingly (discussed below) even at its entrance. The impact of the treatment on the dissolved O2 and pH (Figs. 6C and 6D) is also pronounced. The decline in O2 level at the marina center, 66 h after the treatment, is likely due to declined photosynthetic O2 formation with the cessation [MH1] of the cyanobacteria and increased rate of consumption due to respiration of heterotrophic bacteria cannibalizing [MH2] on the dying cyanobacteria cells.  Note that the pH and DO measurements detected in the interior of the marina were statistically different (p≤0.001) from those of the open Lake suggesting improvement of the water parameters due to the treatment.

Finally, we re-draw the attention to the remarkable, statistically highly significant (Fig. 6), differences between the lake waters and marina entrance (where scums of cyanobacteria are driven by the wind into the marina, (Fig.1). As an example, the RI was similar in all the sampling points 7 hrs prior to treatment but significantly different 18 hours after the treatment. This trend was sustained during the four days of measurements. The RI at the marina’s neck was closer to the marina’s interior than to the Lake.

To gain a better understanding of the drivers of this remarkable differences we collected water from two sampling points (shown in Fig. 7) in the lake itself and the entrance to the marina, 25 meters apart from each other, before and 42 hours after the treatment. Microscope examination tells the whole story of this unique campaign (Figs. 7 and 8). Following the treatment, cyanobacteria from the Lake underwent lysis at the entrance to the marina.

The dominant organism in Utah Lake (during the study) was a filamentous cyanobacterium, Anabaena sp., that formed millimeter long clumps. On the other hand, the organism that dominated phytoplankton population in the marina entrance, shortly after the treatment, was a eukaryotic, non-toxic green alga Chlamydomonas sp. (round/oval shape with two flagella).  More studies are required to clarify the basic mechanism whereby the treatment applied acted like a wall mitigating/inhibiting/killing (??) the toxic cyanobacteria right as they entered the marina. But, from the practical aspects, this is a remarkable phenomenon that can be used to keep the marina cyanobacteria free, with a relatively low cost but high efficacy. Considering the very low concentration of product applied it is not surprising that we could not detect an effect on the fauna or flora populations.

Fig. 7. A photograph of two vials containing lake water that was collected from the entrance of the marina (left vial) and the Utah Lake (right vial). The phenotypic differentiation of the floating phytoplankton in the vials is staggering: in the right vial (Utah Lake), big clumps of Anabaena sp., and Oscillatoria sp., millimeter long, are observed forming a classic floating layer. In the left vial (marina neck), on the other hand, a sample that was taken ~25 meters from the previous one, the phytoplankton formed a hazy floating scum, composed mainly of Chlamydomonas-like sp. as well as unidentified bacteria species. Anabaena sp. and Oscillatoria sp. also appear in the samples but appeared “fragmented” (significantly smaller than in the previous vial). All samples were recorded using the same microscopic magnification (X10).
Fig. 8. Water samples that were collected from the marina’s dock (sampling point “A”) composed mainly of Chlamydomonas-like sp. as well as heterotrophic bacterial species (unidentified). Some “fragmented” Anabaena sp. and Oscillatoria sp. can also be observed. All samples were recorded using the same microscopic magnification (X10).  


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