Those ‘weeds’ in your retention pond? They’re a good thing

By Alex Figares

Southwest Florida isn’t known for its lakes, but that doesn’t stop real estate developers from naming their communities after them. Saturnia Lakes, Kings Lake, the Lakes of Estero and on and on.

Often the “lakes” aren’t actually lakes, but instead are stormwater retention ponds. They capture stormwater runoff and prevent flooding. Over the years they have become an integral part of Florida development.

Wetlands are Florida’s natural stormwater system, according to the Southwest Florida Water Management District. The district is in charge of permitting stormwater systems to developers.

However, agriculture and housing development have drained more than half of Florida’s original wetlands. By the early 1980s, stormwater runoff was the main source of pollution in Florida waters, the SFWMD said. As a result, laws were passed that required stormwater to be treated. Retention ponds, in part, serve that purpose. When it rains, greases from roads, rooftops and pavement slush into these stormwater ponds, known as runoff.

The responsibility for retention pond maintenance typically falls on homeowners and property owner associations. That’s where the problems begin, said senior ecologist at Johnson Engineering David Ceilley.

“People put fertilizers on their turf. They put pesticides on their turf to kill the bugs that eat the grass, and they put herbicides to kill the weeds,” Ceilley said. “All that stuff eventually ends up in these ponds.”

Another issue Ceilley said, is people often want the ponds to look “beautiful” and “blue” all year round.

“When they [homeowners] see vegetation, or they see what they consider to be weeds, they don’t understand that those plants perform an important function,” Ceilley said. “They stabilize the soils, they absorb nutrients, they absorb carbon, they provide a lot of ecological functions, and remove pollutants.”

Additionally, the plants get in the way of recreational activities and have to go.

Chemicals in moderation are not always harmful, said biologist Ernesto Lasso De La Vega, who works at the Lee County Hyacinth Control District.

“We [Lee County] don’t overuse these chemicals,” Lasso De La Vega said. “These plants can build resistance just like bacteria. You can treat the same thing over and over and eventually it doesn’t work anymore.”

Native plants like pickerel weed and spike rush dot the shorelines, capturing runoff and nutrients, treating the pond naturally.

But when homeowners kill these plants, nutrients are released back into the water, which can adversely affect the pond’s ecosystem. It can also cause algae blooms, which can emit unpleasant odors and soak up oxygen in the pond, killing wildlife.

To treat algae blooms or simply to remove vegetation, homeowners hire retention pond management companies.

“A lot of companies will sell you on a quick fix, which is copper sulfate,” Ceilley said. “It kills the algae, and then three months later the algae comes back with a vengeance. So, then, you have to hit it again. Well, you’re poisoning that pond.”

Complicating this is that, over time, sediment piles at the bottom of the pond, creating muck. Heavy metals like copper sulfate tend to sink to the bottom of the pond and accumulate, Ceilley said. The muck should be removed to keep the pond functioning, he said. Otherwise there’s a “turnover.”

A turnover is when water at the bottom is suddenly brought to the top by heavy rain. This can cause the metals to be released into protected Florida waters like Estero Bay and degrade the water quality, Ceilley said.

Ceilley says homeowners need to be educated.

“Homeowners take over the pond management responsibilities and are afraid that there (are) venomous snakes, and rats and vermin,” Ceilley said. “I heard that many times. But, through education, you can often change their minds.”

Ceilley encourages homeowners to get involved with their homeowner association and to plant non-invasive vegetation along pond shorelines.

“People need to take responsibility for managing that [retention ponds] correctly in accordance with stormwater regulations and in accordance with state law,” Ceilley said. “There’s a legal obligation and a moral obligation in my mind. What kind of legacy do we want to leave our kids if we keep literally polluting our own backyard?”