Will more roofs and residents mean more storm water runoff for one Bonita Springs community?
With construction of a 350-home housing development on a disused Bonita Springs golf course set to move forward, a neighboring subdivision that controls water runoff is concerned about what this will mean for the community’s drainage system and water quality despite plans showing improved storm water management and less flooding.
The development was approved by a city council vote earlier this month.
The east border of the San Carlos Estates Water Control District, between Old 41 Road and Paradise Road, looks onto the fairways of the abandoned Bonita Springs Golf Course and Country Club.
Since its inception in 1969, the now 800-home community has maintained the drainage system that controls its stormwater runoff, as well as from others outside the district. Because of population growth, the district is looking for aid.
“We’re headed for a trainwreck,” SCEWCD resident Jim Bradford said. “Everything that comes into these canal systems and all through these cross-streets with the ditches all dumps into [our] canal system.”
Bradford said the residents of the estates pay about $400 in yearly taxes to maintain the drainage system. The east border lies outside of the district and collects runoff from neighboring communities through four drainage pipes.
“The fault with this is that these [subdivisions] don’t participate, but they drain into our system,” he said.
Bradford, who is the SCEWCD chairman, said that the system was able to retain water more efficiently decades ago — without needing to be drained into the Imperial River — because there were fewer homes.
“It’s all getting drained off early, which is going to be a water issue with Southwest Florida itself,” Bradford said.
The Imperial River, a 9-mile creek that runs through Bonita Springs and Bonita Bay, flows to the Gulf of Mexico. Its headwaters are east of Interstate 75, in the Flint Pen Strand Trails.
Today, newer structures tend to be larger than they were in the 1950s and 1960s, which has resulted in more tree removal and less impervious surface.
FGCU’s Professor Donald Duke, who has a doctorate in civil and environmental engineering, said that a larger population, more homes and the quick removal of stormwater create problems for the waters in Southwest Florida.
“They keep putting in new communities, but we don’t make the ditches any bigger or make any more ditches because they are expensive,” he said. “That’s a piece of land they can’t put a house on if it’s there for drainage.”
Duke said the community has valid concerns about the drainage. Urban areas generate more pollutants to receiving waters than do open spaces.
“They’re probably right that it will mess with [drainage] even more when it runs off of those buildings,” he said, referring to the new homes.
Duke said the ditches downstream of the estates don’t have the capacity to move lots of rain off landscape rapidly, as residents saw after Hurricane Irma.
“Strictly speaking, that stormwater runoff … if not managed properly, can cause that backup and make your house go underwater.”
In 2017, Irma brought more than 8 inches of rain to Bonita Springs, and the Imperial River flooded. Bradford said drainage backed up and some parts of the estates flooded with 11 inches of rain.
Singhofen & Associates is the consultant that designed the new stormwater management for the golf course. According to its study, 53 homes in the area are at risk of flooding in a 100-year flood under the current conditions. A 100-year flood is one that has a 1% probability of occurring within a given year.
The new stormwater management plans will reduce the homes at risk of flooding to 32 homes. The study did not include SCEWCD.
Bradford worries that the new retention ponds may not be enough.
“There’s a point when those holding ponds are full—hurricanes, major catastrophic rain events,” he said. “We’ve had those without hurricanes.”
After Hurricane Ian, the subdivision paid approximately $80,000 to clean out the ditches, Bradford said. Almost half of those were on the east side of the estates, just outside the subdivision.
The construction includes filling current retention ponds and adding three, including one east of Carnoustie. City Councilman Chris Corrie estimates that it will take two to three years to complete at 40,000-60,000 truckloads of dirt removal.
He said the new design would also take care of any water flowing into the area north of Shangrila Road, just east of SCEWCD.
“What the lakes do is provide for runoff of water that’s been contaminated with fertilizers and other pollutants,” Corrie said. “And as that water sits on those lakes, those pollutants tend to settle out and go to the bottom of the lake.”
Baron Collier Companies, the current owner of the old golf course, is working with contractors to fix stormwater issues outside of the land it owns, including a collapsed pipe east of Divot.
Pipes will be constructed underneath Paradise, running from east to west, that would tie into the drainage system. The open culvert on the east side of Paradise will be dug out so the water flows better and gets carried to Spring Creek, which runs west of the estates.
Still, the water district is concerned about being able to prevent harmful algal blooms from pollutants in stormwater runoff. Duke said blooms happen because of nutrients carried by stormwater.
“The reason there are more nutrients in human-developed landscapes is that we move that stormwater off the land quickly,” he said.
Nutrient runoff causes algal blooms, which change the ecology of the receiving waters.
“The ecosystems that we’ve come to enjoy that so affect our quality of life are sort of clear streams and fish that we like to fish for and organisms that we like to see,” Duke said. “And those get choked out if there’s too much algae.”
FGCU’s Associate Professor Serge Thomas, who has a doctorate in oceanology, said that Florida has more water moving underground than it does above ground and that retention ponds are not a complete solution to nutrients flowing through our waterways.
“People think the ponds are sealed, but they’re not sealed because they are connected to culverts or to water structures, overflow boxes, for example,” he said. “And then they’re also connected to the groundwater.”
Thomas said that anyone southwest of the golf course, where parts of the water district sit, should be concerned about groundwater getting into ditches and lakes. Across Southwest Florida water flows from the northeast to the southwest, and underground water has no boundaries.
The plans for the new stormwater management will alleviate some of the east-side runoff into the water district and dump it into an 8-acre pond. Dwight Esmon, east of the estates, sees this as a tradeoff.
“Some of the water that comes off our area actually flows into one of their ditches,” he said. “Some of our water will run into their ditch, but some of their water from that same ditch will run into a retention pond.”
One problem he sees is that the older homes were built at ground level and all the homes are on septic tanks.
“When a new home goes in, it will be at 16.5, 17 feet,” he said. “So more impervious area will put more water into their ditches. More water into their ditches will start possibly backing things up. And when it backs up and starts flowing into the lawns and houses at ground level, their septic systems will not work, and pollutants will get into the water and flow into Spring Creek.”
Spring Creek is 6.3 miles long, and it starts east of Old 41 Road and flows into Estero Bay. The headwaters are at the golf course and south of the estates.
“If you have a heavy rainstorm and the lakes are already pretty full, then the polluted water … runs right into the lake, right through the lake, right down into whether it be the Imperial River, the Cocohatchee, the Caloosahatchee or Spring Creek,” Esmon said.
Bradford’s goal for the estates is getting Bonita Springs, Estero and Lee County to work together with the water district with either funding or keeping the drainage system clean.
Elly McKuen, the City of Bonita Springs senior project manager, said the district does a good job controlling water.
“They control how their water flows and where it’s captured, where it reduces [and] the impacts,” McKuen said. “When we did our study, we only took into consideration the neighborhoods that were surrounding the golf course.”
However, she said the new housing development will not affect SCEWCD.
“We hired an expert to do hydraulic and hydrology studies, and [it] is one of the national leaders in water management,” she said, referring to Singhofen.
McKuen said that if the district wanted to incorporate the surrounding communities into its water control taxes, it would not be something the city would be involved with.
“If they want to annex those homeowners into their district, they’d have to show them a benefit,” she said. “Most of the onus would be on the district.”
Thomas said nobody wants to pay more for water control and that the state uses low taxes to attract more people to move here, though the area has reached capacity.
“We’re shooting ourself in the foot by doing this because we actually are a very, very sensitive area for nutrients,” he said. “Our system responds to nutrients five times quicker than all of the other states in the United States.”
Bradford believes there is a better way to maintain drainage and hopes that surrounding communities will want to
“Every [SCEWCD] taxpayer pays for maintaining the system that everybody else uses,” he said.
This story was produced by Democracy Watch, a news service provided by Florida Gulf Coast University journalism students. The reporter can be reached at firstname.lastname@example.org