Fish Kill At Mackle Park Lake Reported

It is unclear when the issues resulting in a large fish kill at Mackle Park Lake began, but what is clear is that the problem was a serious one for the neighbors who abut the normally pristine and quiet surroundings.  

On July 15, Coastal Breeze News was notified of the problem by a concerned citizen and chose to visit the site. That visit was a short one, as it was impossible to stay in the area due to the noxious odor that made it difficult to breathe.

Mackle Park Lake is neither a spring nor other fresh water-fed body of water such as other lakes you may be familiar with. It could be better described as a “retention pond” which collects stormfwater. It does have a direct connection with the canal systems which allows flushing of the pond if the grating is kept free of debris so the water can flow, which on occasion has been an issue.

Some speculation amongst those familiar with the area centered on two areas of concern.

* The lack of aeration of the water body.

* Improper use of chemicals to maintain shoreline vegetation.

The aeration of the water body to maintain a healthy ecosystem is an important factor. Miguel Carballo, Manager of Fleet and Facilities for the city, reported that there were, in fact, two fountains within the water body, and both are out of service. The small unit near the dog park has been out of service since 2018. The larger fountain unit is located near the bridge at the north end of the lake and has been out of service for an indeterminate period of time. The most recent update estimates the fountains will be back up and running in approximately three weeks.

Both the “fountain aeration systems,” as well as the “bottom diffusion systems or bubble diffusers,” can also be utilized to provide better oxygen levels and help to control harmful algae blooms and possible fish kills.

On July 31, the city, via Mr. Carballo, provided Coastal Breeze News with an incident report regarding the early July fish kill. There were no changes to the normal processes employed by the city contractor.

The lake management contractor conducted monthly inspections and treated the shoreline grass with an aquatic-approved version of glyphosate that is tested and approved by the EPA to be added to the water column. 

No treatment of the retention pond water was performed, and no chemicals were introduced to the pond. Additionally, no fertilization was conducted by the City’s landscaping contractor or City personnel in the surrounding areas.

The report concluded with these Potential Factors Resulting in July 2023 Fishkill:

1. Change in salinity of the retention pond due to increased rainfall.

2. High temperatures.

3. Stormwater run-off.

4. Fluctuating oxygen levels.

Changing salinity levels in the retention pond, combined with the rise in water temperature (which causes stress on the fish), is believed to be the most likely reason for the most recent incident.

Over 100 fish have been cleaned up in and around Marco Lake since July and Mr. Carballo’s reports continue to show acceptable oxygen levels.

Water samples were taken for a chemical analysis of the water condition and sent to a lab in Tallahassee for testing of a variety of toxins, including herbicide. The results of those tests are expected in a few weeks.

Coastal Breeze News will continue to monitor this issue and other breaking news around the area and keep residents abreast of the details. The full report can be found here.

https://www.scribd.com/document/663601494/Incident-Report-July-2023-MCP-Fish-Incident