Opinion: There’s a nitrogen problem in Charlotte Harbor
BY ROBERT J. ROBBINS AND PERCY ANGELO, CAPE HAZE
Charlotte County operates four wastewater treatment plants that use secondary treatment systems that fail to remove most nutrients such as nitrogen. This means that the treatment plant effluent that is shipped throughout the county as reclaim water for irrigation (the purple pipes) has high levels of nitrogen that are discharged back into the environment. Not surprisingly, Charlotte Harbor has a nitrogen issue, as nitrogen feeds the growth of algae.
The numbers are troubling. Using County test data for reclaim water, we have sent analyses to the County showing that the nitrogen discharge in WTP effluent throughout the County is on the order of 190 tons annually (34.9 mg/L x 1.3 billion gallons of annual discharge) to golf courses, condo associations, and businesses. Unless turf grasses are cut, bagged, and removed, the nitrogen taken up by them simply goes back into the environment as clippings break down.
The West County sewage treatment plants seem to be the least efficient of the County plants in removing nitrogen. Based on data from the county, their effluents are frequently in the range of 20 to 30 mg/L Total Nitrogen.
The State is aware of the problem of nutrients in reclaim water and a statute requires that WTPs be upgraded to Advanced Wastewater Treatment (AWT) to discharge no more than 3 mg/L, a level one-tenth of the levels currently discharged by the West County plants. Yet the county currently has no plans to upgrade Rotonda to AWT, and the upgrade schedule for its other plants is three and more years away.
Besides the delay in improving water quality in Charlotte Harbor, this delay in installing AWT has costly implications for many residents because the County in its Sewer Master Plan (SMP) has pretended that it needs to solve its water quality problems by requiring certain communities to convert their septic systems to sewer. Rob Robbins has researched the technical work underlying the SMP. That work began with a 2013 study of the East West Spring Lake area. That study involved some 50 monitoring wells which for the most part showed no problems. The study reports, “Of the 50+ samples taken during each monitoring period, it is noted that the majority of the wells demonstrated little to no significant impact.” In fact, the majority of samples were below the limit of detection.
The county utility then hired Brian Lapointe who identified three septic systems which had failed and were under enforcement action and tested those. He found high levels of nitrogen at the three locations.
Besides the clear error of testing, opposite of random and designed to show problems, what is also notable is that by the County’s own previous testing of the area it was clear that those three failed septics did not impact the surrounding groundwater. The contamination from them had not spread. Aside from the failed septics themselves, somewhat higher nitrogen levels were basically found along US 41 where they were likely caused by highway stormwater or even leaking sewer lines.
A map showing the test results is attached. The three failed septics are in purple. The initial 50 or so wells in red. And the height of the columns shows the relative degree of the nitrogen readings. The lowest levels are so low as to be below detection.
The decision to study septics by picking the failed ones is like studying a hurricane to understand the everyday weather.
This decision has many unfortunate results. Most basically, it has caused great expense and difficulty for many homeowners forced to convert. It has allowed the county to continue connecting new subdivisions and adding sewage to treatment plants which are not providing effective treatment, then discharging their effluent back into the environment as reclaim. Pretending you are providing treatment, however, does not fool Mother Nature, which means that when the septic to sewer process is done we still will not have eliminated the impairments in the Harbor but will have wasted much money and caused much unnecessary grief.
Sarasota County looked at these very issues and decided to suspend its septic to sewer process and accelerate conversion to AWT.
Full disclosure, our community of Cape Haze is one of those scheduled for septic to sewer conversion. We have specifically asked the county if there is any testing showing problems with septics in our area and have been told there is none. (In fact, groundwater flow for most of West County is toward the west, not toward the Harbor at all).
Reclaimed water is not the only contribution to Charlotte Harbor impairments which need to be studied. Stormwater in the county is also likely a significant contributor to nitrogen in the environment as it picks up fertilizer, reclaim, and other nitrogen sources on its way to our harbor. Stormwater, reclaim, sewer line breaks (frequent in Charlotte), and failed septics need to all be considered.
