NAPLES — Using reclaimed water to keep Naples lawns lush and gardens green could be coming with unintended — and eco-unfriendly — consequences.
The concentrations of nutrients in water samples taken from areas where homes and businesses use treated effluent were “significantly greater” than concentrations of nutrients in water samples where reclaimed water isn’t being used, according to an engineers’ report the Naples City Council heard Tuesday.
Nutrients, such as nitrogen and phosphorus, are the main culprits in algae blooms that can cover lakes and waterways in algae or slime and can cause fish kill and human health concerns.
City officials downplayed the finding, pointing out that the reclaimed service overlaps with the Port Royal neighborhood, where they suggested overfertilization might have been causing a nutrient runoff problem even before the reclaimed water hookups.
Still, the report could help raise public awareness about how to use reclaimed water to limit the amount of nutrients that get into the city’s lakes and bays.
“I don’t think that (reclaimed water) is a major problem,” Naples Natural Resources Manager Mike Bauer said. “It’s more of an opportunity to lower fertilizer use.”
The report found that in areas without reclaimed water service, runoff samples had an average nitrogen concentration of 1.2 parts per million compared to 2 parts per million for runoff from areas with reclaimed water service — almost double.
Average phosphorus concentrations were 0.1 parts per million in areas without reclaimed water service; areas with reclaimed water service had average phosphorus concentrations of 0.37 parts per million — more than triple.
The report didn’t include data that could compare the amount of nutrients in runoff before and after the introduction of the reclaimed water system, city officials pointed out.
“I think it’s more of a fertilizer application issue than a reclaimed water issue,” Naples Mayor John Sorey said.
Households using reclaimed water could cut back on their fertilizer use, concluded Tuesday’s report, which focused on the health of the city’s drainage lakes.
The city’s reclaimed water provides almost 10 percent of the nitrogen a Naples lawn would need; no additional phosphorus fertilizer is needed, the report stated.
Overwatering with reclaimed water, which is less expensive and has fewer restrictions on its use, can cause more nutrients to run off into the city’s lakes and estuaries, according to the report.
The city’s public education campaign about proper use of reclaimed water is “not anywhere near where we need to be,” said Bauer, the city’s natural resources manager.
“We’re just ramping up,” he told council members.
More than 500 households in the Port Royal neighborhood have hooked up to the city’s reclaimed water system, the latest addition to the city’s network that includes 10 golf courses plus another 100 businesses and city parks and medians.
In all, the city pumps out between 6 and 6.5 millon gallons per day of reclaimed water, which includes about 1 million gallons per day of treated water drawn from the Golden Gate canal.
Utilities Director Bob Middleton said the city’s reclaimed water supply could top out at 16 million gallons per day, with additional mixing from the Golden Gate canal.
The City Council also took the first steps Tuesday toward expanding the city’s reclaimed water system along northern stretches of Gulf Shore Boulevard.