Lake George Part 2

Part of a continuing series on Florida's Lakes.

This is Lake George Part 2, the current environmental condition and challenges of Lake George. Here's a link to Lake George Part 1, the history of the lake. If you haven't read it you may want to start there. The history of Lake George is inextricably intertwined with its current condition.

Lake George's Most Famous Resident

I want to look at 2 different measures of water quality in Lake George – the trophic index and turbidity. These measures are related can give us a picture of the lake’s health. I also want to look at a few other threats out there today.

The first piece of data is how trophic the lake is. The term refers to how high the nutrient level is in the lake. The amount of nutrients, especially phosphorus, is related to the amount of algae can grow in a lake. The number graphed is the trophic state index, an easy way of looking at how easily algae blooms can start in the lake. Anything below 60 is considered good and between 60 and 70 is fair.

Nutrient Load

The numbers don’t look to bad over most of the last 10 years. You can see elevated nutrient loads during the drought times in 2007-2008 and also in 2011, but other than that the numbers stay consistently in the good or fair range.  The latest numbers available from the Lake Water Atlas is through 2015.

This is better than most large lakes in Florida. The fact that the St John’s River flows through the lake helps keep the nutrient load at a reasonably low level. The water doesn’t flow through most lakes in Florida nearly as fast as Lake George.

I included the full 10 years of data here because it shows a sustained drop from roughly the year 2012. For several years the lake had been on a Total Maximum Daily Load program through the Florida Department of Environmental Protection (FDEP) concerning the nutrient load. The FDEP kept the program active through 2014. It’s since ceased, but it seems to have brought Lake George into a relatively good place.

Another parameter to look at is the turbidity. Turbidity is the level of suspended particles in the water. Turbidity changes a lot over the course of the year. Rains can cause the amount of solids to increase and turbidity also increases during summer when algae and other plants bloom.

Turbidity for 2 Years

A turbidity value of 10 or less is pretty good for a Florida Lake. Compare this to Lake Apopka (one of the worst in the state) where the turbidity averages around 40 with spikes to 80. Most of the time the turbidity is stayed below 10 over the last few years. Again, the latest data available is through 2015.

The turbidity does spike occasionally. However turbidity can be affected by a recent storm or even high winds. I think the peaks in 2015 are probably just that. But the average values look relatively good.

One last parameter to examine is the mercury content. Mercury gets into the environment due to industrial and waste output. Coal fired power plants are large emitters as are wastewater disposal systems. One problem with mercury is that it's a non-point source. Mercury goes into the water cycle and there doesn't have to be a local source that puts it in the water. A coal plant in India is nearly as bad for Florida water as one in Tallahassee.

Mercury Cycle

The federal Environmental Protection Agency has been tracking the mercury levels in Lake George since 2014. There has never been a reading of mercury in Lake George over allowable limits. However some of the areas draining to the lake have seen elevated levels. This happens in most of Florida in areas with water that don't drain well. Here's a map of the area around Lake George that have had elevated mercury readings.

Mercury Elevated Areas in Red

The red areas have occasionally seen elevated levels. But again the St. John's Rivers flows through the lake keeping the mercury levels within allowable limits. The wetlands around the lakes seem to be the areas that maintain the mercury. Here's a set of EPA maps that show Florida areas that have some mercury problems. Hint:  About all marshes and swamps.

But the overall evidence is that Lake George is in relatively good shape environmentally. The waters have cleared over the years and the nutrient load has dropped somewhat over the last 10 years. There are still challenges -- invasive species rank near the top of the list and nutrient load can still become a problem. But the overall geography and management practices have kept it relatively clean.

I'll quit there on Lake George. My final article on Lake George will be about ecotourism opportunities near the lake.