Florida's septic tanks and pollution
A common narrative blames agriculture for Florida’s troubled waters, but between 2011 and 2015 Lapointe studied the Indian River Lagoon and linked algal blooms there to nitrogen from septic tanks, a “significant and largely ignored” source of nitrogen pollutants to the lagoon. In coastal counties impacted by blooms, he explains, many septic systems fail to meet code requirements for distance between their drain fields and the water table underneath them. The problem is particularly acute during rainy seasons. Rising seas will only exacerbate it, he says.
His study was “a game-changer,” he maintains. “Up to that point, everyone thought it was simply fertilizer runoff and the farmers.” Agriculture isn’t the enemy, he says, it’s us — homeowners.
There’s a dispute about how much of an enemy. Gary Goforth, a water resource engineer and former chief consulting engineer to the regional water regulator, the South Florida Water Management District, says Lapointe overstates the role of septic in estuary problems. Septic contributes less than 10% of the nitrogen loading the estuary, with 85% coming from runoff from farmland and from Lake Okeechobee, Goforth says.
And nitrogen is but one problem in the estuary. Others in a long list include blue-green algae flushed down from the lake, pesticides and excess phosphorous. Septic contributes negligible amounts of some and none of others. But, Goforth says, “we’re all part of the problem. I don’t take to pointing fingers at one industry or another. We’re all contributing to the phosphorus and nitrogen pollution in the state. I want to certainly give him credit for raising statewide awareness.”
Septic’s role in pollution varies depending on the specific water body. Half the septic systems in Florida are in the springs region north of I-4, reports Robert Knight, director of the Howard T. Odum Florida Springs Institute. Some 70% of the state’s springs are contaminated by nutrients, but there are numerous sources, Knight says, including agriculture and septic tanks.
Edie Widder, scientist and co-founder of the Ocean Research & Conservation Association in Fort Pierce, an active monitor of Indian River Lagoon health, says it would be wise to prohibit new septic systems where possible but adds that converting septic to central sewer systems is no panacea. “We have a lot of leaking sewer systems,” she says. Plus, central sewage treatment yields “biosolids,” the leftover sludge that often is converted into fertilizer. It’s been implicated in rising nutrient levels in watersheds where it’s spread.
Widder notes that people use reclaimed water — “as they should” — for irrigation, but that water also holds nitrogen, a double-whammy when people fertilize their lawns and then irrigate with nutrient-rich wastewater. She and Lapointe advocate upgrading central systems to remove nutrients. Tallahassee did so after its treated wastewater was deemed responsible for polluting Wakulla Springs. That left septic as the largest category of contributors to Wakulla pollution.
After Lapointe’s paper came out, the Florida Chamber of Commerce approached him — not to fund his work (his funders largely are federal agencies and local governments) but to pay $90,000 to Harbor Branch to produce four videos featuring Lapointe and a diverse group of scientists and experts speaking about Florida’s water issues. The chamber has arranged for him to speak annually at its Future of Florida meetings and at other events. “The last people I thought would kind of endorse my research,” Lapointe says.