On 11/3/21 Lake Okeechobee was at 15.83 feet (-0.05 feet in the past week) and has stabilized at this level since early-mid October, but is still above the optimal ecological envelope for the Lake. The weekly average flow at S-79 was 1,418 cfs (cubic feet per second) this week. The 14-day average flow on 11/3/21 was 1,157 cfs and has been in the optimal flow envelope (750 - 2100 cfs) for 15 days. As flows from the watershed decrease with minimal rainfall in the region, lake releases from S-77 may increase to provide water supply for agriculture, maintain optimal flows for salinity at S-79 and to try to achieve lake levels within the ecological envelope.

For more information on Lake Okeechobee and estuary conditions go to the latest Caloosahatchee Conditions Report

Wet season is over with the official start of the dry season beginning on 10/17/21. We had an overall average wet season with 33.68" of total rainfall across the South Florida Water Management District. Heavier rains are forecast for the district overnight Thursday through Friday afternoon, leading to substantial run-off in a short period of time.

Each week, we provide information regarding red tide and blue-green algae based on satellite imagery maps published by NOAA’s National Center for Coastal Ocean Science. The processed satellite images NOAA provides are powerful tools for understanding when and where algae occur in the Florida Gulf Coast and Lake Okeechobee. The images are captured by the European Space Agency’s Sentinel-3 Ocean Land Color Imager (OLCI) sensors that detect different wavelengths of solar energy reflected from the earth’s surface. The wavelengths characterize different properties, such as colors of the visual spectrum, which are used to identify harmful algal blooms which reflect specific parts of the spectrum. There are two Sentinel-3 satellites orbiting the earth, each with a revisit time of 2-3 days. The two satellites working together can capture almost-daily images of South Florida resulting in composite images taken on multiple days, reducing the effects of cloud coverage obscuring the image.

Chlorophyll-a is the most-common pigment in algae. It absorbs certain parts of the light spectrum to create energy via photosynthesis. The light that is reflected back is in the green part of the visual spectrum, which is detected by the satellites’ sensors. As such, the imagery refers to all algae living towards the surface of the water. NOAA’s red tide monitoring map (left image) displays the chlorophyll-a fluorescence under a layer of field-verified samples of the red tide causing organism Karenia brevis collected by several contributors along the coast. If medium and high K. brevis concentrations align with high chlorophyll-a fluorescence, it is likely that there is a red tide bloom occurring. The chlorophyll-a fluorescence displayed by the colorful pixels is calculated using a method called red band difference, which serves as an approximation for relative chlorophyll-a and has no units. The more orange or red the pixels, the more chlorophyll-a is present in the water.

The NOAA satellite imagery data for Lake Okeechobee (right image) consists of two side-by-side images: the left showing a true color image of the lake and the right showing a processed image of the lake. The true color image shows what we would see if we looked down on the lake from the satellite’s perspective and how clouds may be obscuring the data. The image on the right shows the concentration of cyanobacteria cells (cells/mL) calculated from the data captured from the satellite and where blooms are forming. The color bar represents different concentrations of cyanobacteria. Black pixels show that there were no clouds in the way of the satellite, but no cyanobacteria were detected, and gray pixels show that data was not able to be collected due to cloud coverage or similar obstacles.

In addition to chlorophyll-a, cyanobacteria contain phycocyanin, which fluoresces at a different wavelength than chlorophyll-a. So, unlike the red tide images, which detect all algae, these images refer specifically to cyanobacteria. The cell concentrations in the images of Lake Okeechobee are calculated using a method called the Cyanobacteria Index (CIcyano), which can differentiate cyanobacteria from other algae by first estimating cell concentration, then ensuring phycocyanin is also detected. By detecting the intensity and location of cyanobacteria we can see where blooms are occurring with respect to where water is released to the Caloosahatchee, informing water management decisions to prevent nutrients and HABS being transported downstream. 

https://content.ces.ncsu.edu/supporting-cyanobacterial-bloom-monitoring-with-satellite-imagery. Accessed: November 4, 2021.

Lunetta, R.S. et al. (2015). Evaluation of cyanobacteria cell count detection derived from MERIS imagery across the eastern USA. Remote Sensing of Environment, 157(), 24–34. doi:10.1016/j.rse.2014.06.008 

Wynne, T. T. et al. (2018). Harmful Algal Bloom Forecasting Branch Ocean Color Satellite Imagery Processing Guidelines.doi:10.25923/606t-m243

Satellite imagery over the past week has shown low to moderate concentrations of chlorophyll off the coast of Southwest Florida. Karenia brevis and/or other algal species may be contributing to the chlorophyll concentrations.

FWC samples in Lee county had background to low concentrations of Karenia brevis. The Clinic for the Rehabilitation of Wildlife (CROW) on Sanibel received 10 birds with toxicosis symptoms (from red tide or blue-green algae) from 10/24/21 - 11/1/21.

The FWC fish kill hotline continues to receive reports of red tide related fish kills in Pinellas (1 report), Sarasota (1 reports) and Manatee (1 report) counties. They are also receiving reports in the panhandle related to red tide.

No cyanobacteria was present in the Caloosahatchee over the past week. On 10/31/21 satellite imagery showed algal blooms covering about 200 square miles of Lake Okeechobee.

To learn more about our current water conditions, click on the following links:

A collaborative, weekly analysis, including recommendations for water managers regarding Lake Okeechobee flows.

SCCF's River, Estuary, and Coastal Observing Network is a network of eight optical water quality sensors deployed throughout the Caloosahatchee and the Pine Island Sound estuary to provide real-time water quality data.

Algae Reporting App.

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