Current Issues

↑ Harbor Isle Public Entrance | August 2020

Where is the majority of the lake view? How can the public / residents observe the water for current toxic algae blooms?

Entire access will be gone as the cattails continue to fill in, in the coming months.

After 3.5 years of massive toxic blue-green algae blooms -- what the city has done is not enough and long overdue. The lake is not better, just potentially less bad at this point in time. The submersed aeration system is one that must be observed and optimized-- among other factors below, to be considered.

Sub-optimal Design of June 2020 Micro-bubble Aeration Install - Likely Not Enough Oxygen and Circulation to Control BGA and its Nutrient Sources in Entire Lake

Additional Considerations for Improved Micro-bubble Diffusor Performance: Evaluating the previous bathymetric map and additional bottom sediment hardness data map collected for Harbor Isle Lake along with the supplemental City storm drain diagram, all of which were e-mailed to the homeowner's association and City in June 2020. This information would be highly beneficial to the planned micro-bubble aeration system’s optimization. Reviewing and including these important factors about our water body, could enhance the micro-bubble aeration system’s performance, improve efficiency, and reduce overall project risk while improving the lake’s entire water quality. The design/placement were not explained despite requests. At this time, the design appears inefficient based on nutrient run-off input loading analysis, lake morphology, and the extent of blue-green algae dominance.

No beneficial bacteria considerations to help encourage micro-bubble aeration's effects

Supplementing the system with "good bacteria" helps the bottom water have more aerobic producing bacteria and oxygen levels. It helps speed up the environment, the micro-bubble aeration system, is trying to create. More oxygen means higher chance of nutrient reduction. So, less muck and less usable nutrients to sustain algae blooms.

Sediment and Fill Material Remains Present - Dredging Requirement to Control Nutrient Leaching

Resident supplied proof and the City's overdue completed sediment report in September 2021 demonstrates extremely high nutrient levels in this material. Dredging may be required to remove the large amounts of 2001 fill material in the lake, which is now a confirmed major source for leeching out of nutrients to sustain algae blooms. If large amounts were removed, then these other proven methods of improving water quality would have a greater chance of being successful.

Micro-Bubble Aeration Solution not guaranteed / stated to be permanent

At the July 2020 homeowner's association meeting, the City’s Contractor did not answer when directly asked if this micro-bubble system was going to be a permanent system. Even though, all scientific case studies say it must be permanent: in order for water quality to be improved and maintained. Otherwise, it will revert back.

The only scientifically proven plan of action is keeping a properly designed submersed aeration system to mitigate uncontrollable stormwater run-off pollution, and natural loading events (like bird waste).

↑ Toxic Green Water and Toxic Residue on Cattails | Aug 2020

This is an example of the toxic blue-green algae coated cattail reeds that residents are forced to remove themselves. They want to remove them in order to reduce the likelihood of trap toxic scum mats, smells, added nutrient decomposition which is bad for the lake, and to manage /prevent cattail growth.

Why doesn't the City, with their stormwater resources, assist in managing this anymore?

Reduction or No Lake Shoreline Visibility or Access due to Excessive Cattails / Unmanaged Invasive Vegetation

The excess unwanted shoreline vegetation severely hinders the lake monitoring process by residents and has an overall nutrient and organic waste contribution to the lake with its subsequent negative effects. When the lake shorelines are completely filled with cattails (or other tall vegetation like vertiver grass or normal weeds) then the observations from the public walkways are obstructed. Therefore the views of the water surface and water clarity are extremely hampered. Cattails may enable the possible transmission of the blue green algae (cyanobacteria toxins) to become airborne via dried residue on the cattail stalks/reeds.

Several times a year, increased nutrients and organic decomposition (muck) is generated due to normal life cycles where the cattail reeds die and are deposited into the lake.

City is now refusing to spray/kill cattails and/or remove/eliminate them for residents who request this city service for retention ponds - under stormwater management. Therefore, residents and other contracted workers have been forced to come into contact with contaminated water with toxic algae blooms during vegetation extraction. The residents incur the total health risks and physical or monetary cost of removing, maintaining or controlling cattail growth.

City has failed to act on their own 2019 permit initiatives to control the invasive cattail growth and other Florida invasive vegetation via spraying and/or mechanical removal.

Reduction and/or elimination of easy access to the lake for City stormwater crews and lake management contractors to enter the lake (for example at the block entrance lake lobe area). Therefore, workers with their equipment are forced to run over home owner’s properties and damage the bank and/or surrounding area. Typically, the cattail reeds or other vegetation are cut or dislodged leaving them to float and decompose in the water as further organic debris.

'No-Mow Zones' add to unmanaged vegetation and provide harborage for rats, snakes and pests, while preventing easier access to the water.

Lack of Answers and Access to Public Info

No place to review reports online and current timeline to lake's solution provided by the City

Many Residents still in the dark about the lake even being toxic in the past year, no transparency of information and plans and answering of questions. City redirects to homeowners association, and homeowners association redirects back to City. Therefore, there is never a answer or someone actually accountable to answering.

Negative Effects/Disadvantages of opening the berm as a Lake Water quality Solution

Tidal or limited tidal flushing will not get oxygen to the bottom of the Harbor Isle Lake.

Salt water will not correct the problem. Dilution or flushing just allows the problem to be transported to expanded pristine protected waterways without correcting the underlying problem - no oxygen at the bottom of the lake.

The Weedon Island Preserve’s waterways surrounding Harbor Isle neighborhood are protected by strict and restrictive Federal and State guidelines due to its Outstanding Florida water category. Tidal currents via a partial opening of the berm or its complete removal would allow contaminates from Harbor Isle Lake to be released (flushed) directly compromising its precious water quality. It would increase pollution to the surrounding waterways and shoreline areas which is a sensitive aquatic preserve environment and is where many people recreate (swim) in the water and/or consume fish caught in those waters.

This would also increase Harbor Isle lake bank erosion effects due to 2 tides per day every day. It would also lower the lake’s overall water level by 1 to 3 feet depending on the seasonal tidal cycle. This would expose a significant risk of erosion for the unprotected/vegetated shoreline or existing seawalls or undermine rip rap erosion control systems already in place.

Exposing all 68 Harbor Isle lake front homes to any and all storm surge damage when they are presently protected by the our existing earthen berm.

With a tidal connection to the bay waters, there would be expanded and severe Federal and State restrictions placed on the lake property owners due to their shoreline being included in the Weedon Island Preserve waterways. EPA and State level oversight and water quality regulations as well as any other shoreline regulations for lake front homeowners that have no such restrictions at the present time.

The original Harbor Isle developer is the berm property owner and owns the land at the bottom of the lake. The City would need the written legal approval from the developer to pursue this course of action. The developer never agreed to the City’s temporary berm removal for the 2001 Harbor Isle Lake fill project.

Prior Issues:

Addressed: September 2021 - City has in their possession a completed contracted sediment report, which confirms Extremely High Nutrient levels in sediment / fill material.

Sediment and Fill Material Remains Untested for Nutrients

Sediment continues to be a huge unrecognized influencing factor to the lake. Despite, resident supplied proof that illustrates the need for further investigation (Extremely High Nutrients). The City ignoring its existence is problematic and hinders the ability to make proper decisions in this remediation project.

Addressed: December 2, 2021 - City Contractor removed the 4 nano-bubble generator units on land, (1 located at the Southern Entrance Lobe, and 3 on the berm). The long lengths of PVC pipe used for these units was left in the water, and extensions of same pipe, were left all along the berm's land too, acting now as pure plastic trash in the environment.

Potentially Addressed: Week of November 18, 2020 - Nano-bubble Unit (Neighborhood Entrance) has been turned off, and it remains off. The City has not updated the residents on the status of those nano-bubble units and if all additional units are in fact off and no longer being used. The City's conclusions on that experimental system has not been presented or shared with residents.

As of April 2021, the entrance generator is running again, without explanation. City report conclusions stated this system was ineffective, but these results have never been publicly stated to residents by the City or addressed in future plans for the lake.

Potential Data Collection Issues when Running Both Aeration Systems Simultaneously

The apparent decision to continue running the nano-bubble aeration system in tandem with the new micro-bubble system creates a confluence and data conflict. Simultaneously running dual aeration systems confounds the accuracy or the correlation between their intended effects (results). Turning off or removing the nano-bubble generator system that has not been performing well would allow for the micro-bubble system to be the only system running. This would provide direct clean baseline measurements to observe the micro-bubble system’s effectiveness in same lake during a similar time span. Also, keeping the additional nano-bubble system running would require an excess use of electrical energy and therefore, higher monthly running costs.

Addressed: June 11, 2020 - City Contractor Installation of Submersed Micro-bubble Aeration Units

Currently Installed Aeration System does not get oxygen to the bottom of

Harbor Isle Lake

The current nano-bubble aeration system is not effectively providing oxygen directly to the bottom. Therefore, nano-bubble aeration will not directly or efficiently resolve this important water quality problem in a reasonable time period or possibly ever for Harbor Isle Lake.

Alum (aluminum sulfate) and algaecide (GreenClean 5.0) spraying treatments do not address the lack of oxygen at the bottom of the lake -- they are nutrient and algae treatments for the temporary reduction of symptoms.

Placing micro bubble diffusors at the bottom of Harbor Isle Lake is the only way to directly and immediately provide oxygen and the necessary circulation of the total water column.

Addressed: June 11, 2020 - City Contractor Installation of Submersed Micro-bubble Aeration Units

Intentionally Excluded/Ignored Micro-Bubble Aeration System Solution

A micro-bubble aeration system by design would correct the deficient oxygen levels at and near the lake bottom by utilizing a continuous laminar fluid flow to recirculate the bottom water to the surface.

The City has failed to reply for almost a year to many questions, especially as to why micro bubble aeration, a successful and well-proven method with a long well documented history, was not pursued sooner. In fact, it was excluded from being considered and compared in their competitive bid request in July 2019.

The City continues to keep running an inefficient and/or inadequate system, instead of replacing it with a properly designed micro-bubble aeration system. This choice could have eliminated or reduced the need for supplementary chemical treatments. As similar case studies have demonstrated and nearby Renaissance Lake micro bubble aeration installation has shown.