Red tide bloom becoming more patchy off Lee County

Red tide off the coast of Southwest Florida is becoming a little more patchy as fewer high counts were reported this week. 

The Florida Fish and Wildlife Conservation Commission report on Friday shows concentrations ranging from natural, background levels to 1 million cells per liter and higher. 

The National Weather Service added Lee County back to the list of counties where hazardous beach advisories are in place through at least Thursday evening. 

Similar conditions exist in Charlotte, Manatee, Sarasota and Pinellas counties. 

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Red tide naturally occurs in the Gulf of Mexico although water quality scientists say it can be fed by nutrients running off urbanized areas and farming operations. 

This bloom was first documented by the National Oceanic and Atmospheric Administration on Oct.16 and is the longest since an outbreak that lasted from the late summer of 2004 until the spring of 2006. 

Counts since then have ranged from natural, background concentrations to upwards of 200 million cells per liter. 

Breathing irritation and fish kills can start when levels reach 10,000 cells per liter, according to the FWC. 

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Counts in Lee County this summer have ranged from not present to 1 million cells per liter and higher, according to FWC reports. 

Some red tide experts have said the bloom may be in place until January or February, when cooler temperatures and heavier winds from the north make bloom formation difficult. 

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The bloom extends along 135 miles of coastline and is at least 28 miles offshore in some places, according to FWC records. 

Counts offshore of Collier have measured 1 million cells per liter and higher, and concentrations along the coast have been low in the northern part of the county. 

The University of South Florida's College of Marine Science predicts the bloom will move to the west and offshore over the next three days. 

Connect with this reporter: Chad Gillis on Twitter.