Let’s begin with understanding what a health advisory is and when they are issued. The Department of Health samples local water bodies where people frequently swim for fecal bacteria. As the name implies, these bacteria are associated with feces – waste in the water. And, as you can imagine, this is not healthy. However, the bacteria they sample for are typically found in the intestines of birds and mammals. Birds and mammals often defecate, many times into local waterways, and so finding these bacteria in a sample is not that unusual, and not necessarily “unhealthy”.
The bacterium used as an indicator for saltwater systems is Enterococcus. This, again, is a bacterium found in birds and mammals. It is assumed that at high concentrations, higher than nature may provide, is due to human waste. Human waste should not be found in area waterways but is. It reaches there when septic tanks leak, and sewer drains overflow. Enterococcus itself is not that unhealthy for you because it is found in your large intestine. But too much of anything is bad, and it is also assumed that if human waste is in the water, other pathogenic bacteria associated with human waste could be present. So, if the levels are too high a health advisory will be issued.
Too high in the case of Enterococcus is 71 colonies / 100ml of sample. In the Pensacola Bay system, samples are pulled on Tuesdays from one of 13 local swimming areas. They are analyzed in a lab and if the bacteria count is 71 colonies or higher, they take another sample to be sure. If this second sample also registers 71 colonies, or higher, then a health advisory is issued. It is noted here that a count of 71 or higher from one of the three main bayous (Chico, Texar, or Grande) does not require a second sample before an advisory is issued. Due to the bacteria issue of these three, they can – and often do – issue the advisory on the first sample.
It should also be noted that they do not sample all 13 locations every week year-round. Lab analysis is costly and with tight budgets they will only sample them when people might be swimming – this being spring, summer, and fall. For some of the locations, it will only be summer. So not all are sampled at the same frequency. Three locations, Bayou Texar, Bruce Beach, and Sanders Beach are sampled year-round.
So, when comparing one to another you cannot just look at who had more advisories issued. If one is only sampled 20 times compared to another who is sampled 50 times, the one sampled 50 times could have more advisories and appear to be more “polluted”. When in fact they were just sampled more frequently. So, I chose to look at what percent of the samples pulled required a health advisory.
I have been looking at these for over 10 years. The trend is that most swimming areas have less than 10% of their samples requiring an advisory. Most of those in the lower part of the bay are usually less than 5 % and often no advisories are ever reported. Along our barrier island beaches health advisories are very rare indeed. However, the bayous are different. These are usually above 30%. Bayou Chico is usually close to 50%. There have been years when Bayou Chico is close to 60%.
There seems to be a correlation between rainfall and health advisories. The more it rains, the higher the bacteria count, the more advisories issued. However, members of the Bayou Chico Association have told me there are high levels of bacteria even in years when rainfall is not high – and they are correct. Bayou Chico is one of the state’s oldest BMAP sites and this is due to the bacteria levels there. BMAP stands for Basin Management Action Plan and is required by the state if the waterway is consistently reported as unhealthy because of one of their indicators that makes water unsafe to swim in – fecal bacteria being one. In the last decade the annual rainfall in our area has increased from an annual mean of 60-61 inches each year to more than 70 inches each year. If this correlation is there, there should be even more advisories coming.
What happened in 2022?
Below is the table that gives the answer.
|Body of Water||Number of samples taken||Number of POOR readings (> 71 colonies)||Number of Health Advisories Issued||% of samples requiring an advisory|
|Big Lagoon SP||18||4||0||.00|
First thing to note is that not one site reported 30% or higher. This is the first time since 2012 (when I began monitoring these reports) that I have seen this.
Second thing to note is that the higher frequency of advisories continues to be the local bayous and it is there that we need to focus our efforts to reduce this problem in our bay.
Third thing to note is the number of POOR readings (>71 colonies) was higher at Big Lagoon SP than other nearby bodies of water. I can also add that we are monitoring surface salinity at many of these locations and the mean salinity for Big Lagoon SP is much lower than the surrounding bodies of water. I am not sure why this is, it seems to be something new, but will be of interest in 2023.
Fourth thing to note is though the percent of samples that required a health advisory near our barrier islands this year was 0%, many of these had at one sample that DID report 71 colonies or higher. The repeat sample did not show this, and no advisory was issued, but it appears that there was a rain event large enough to flush bacteria that far south in our bay.
Fifth thing to note is that our annual rainfall this year was closer to the historic 60 inches / year. For 2022 the NOAA station reported 66.64 inches.
It was actually a pretty good year for health advisories locally. Though we would all like to see 0% for all bodies of water, we must understand that we have many septic systems that are not properly maintained, leaking, or placed in bad locations. And we have sanitary sewer overflows due to heavy rains and blockage in the pipes due to what we pour down the drains. As long as these continue, we will see health advisories issued. It is encouraging that they are lower this year and we will monitor these reports again in 2023 to see if this remains.
In the meantime, we will post articles on how to properly maintain your septic or sewer to help reduce this issue.