'FLOOD-PRONE': As the ninth rainiest city, Tallahassee is perpetually at war with stormwater
Tallahassee is the ninth rainiest city in the contiguous United States, and it shows.
The rain comes down in sprinkles during sun showers and by the buckets from gray ominous skies. In summer, you can pretty much set your watch by it. Water rescues of trapped city residents used to be routine. Two boys were swept to their deaths on Franklin Boulevard in the 1970s.
Each year, all the showers and drizzles add up to more than 59 inches of rainfall. For Florida's capital city, sometimes that means roads and neighborhoods are inundated with muddy rising water. There's nothing like water rushing downhill from Macomb Street on Tennessee Street during an afternoon downpour.
Heavy rains earlier this month led to an overflowing stormwater retention pond at the new development Canopy at Welaunee and a flooded neighborhood street. Last week, a video surfaced of motorists navigating through surging runoff on Capital Circle Northeast.
All of that water has to go somewhere. The network of storm drains, ditches, pipes, holding ponds, lakes, and basins helps it along. The city's history, geography, and geology make flooding a fact of life – despite the millions of dollars invested in taming nature's watery excesses.
“We’ve got rolling hills and clay soils mostly here in Tallahassee. As you get more topography and clay soils, they don’t have the ability to absorb that rainfall,” said Tallahassee Stormwater Manager Jodie Cahoon. “It’s an urban environment with a lot of sidewalks, parking lots and walkways. All of those things produce more runoff.”
Florida's proximity to the active tropics – most of the planet's rain is centered around the equator – is the driving force behind why it rains so much in Tallahassee.
Mix in the warm waters of the Gulf of Mexico and the capital city is in a prime location for heavy annual rainfall, said National Weather Service Meteorologist Wright Dobbs.
"Being on the edge of the tropics, we're in a climatologically favorable part of the world for rain," he said, noting that a third of Tallahassee's annual rainfall comes in June, July and August. "Typically, anytime you're near a warm body of water, you're going to have higher rainfall amounts.
It’s summer. Bring on the deluge
When you combine the natural with the manmade, summer deluges and square miles of asphalt and pavement, along with the mix of city, county, state and federal roads, it's a wonder there isn't more flooding.
In the past month, local residents have seen almost seven inches of rain. That’s 2 ½ inches above normal. That has been pockmarked by a week of heavy storms in early August.
On the evening of Aug. 14, dark skies dumped several inches of rain on certain parts of the city. The official total at the Tallahassee International Airport was .65 inches. In Southwood, almost 2 inches of rain fell, indicative of the summertime pattern of spotty storms likely to persist into late September.
“It’s just a part of the Florida weather; these heavy downpours in the summertime,” said Leon County Emergency Management Director Kevin Peters. “The unfortunate thing with these storms is, they drift in off the Gulf and there’s not much wind to push them around. They can produce heavy amounts of rainfall in a certain place over a short period of time.”
Flooding is all about timing. The ability of the drainage system to take surface water to basins – ponds, lakes and into the ground – depends on the volatility of the weather. A heavy rain after a drought is vastly different to rainfall during a wet spell.
How much rain falls over a given time and the other factors associated with what is categorized as a rain day, or at least ¼ inch, can make a big difference in flooding.
“If the ground is wet and then you get an intense rain event, your potential for flooding increases exponentially,” Cahoon said.
Not a new problem
Despite Tallahassee's reputation for being a hilly, rainy place, the focus on maintaining drainage and stormwater wasn’t regulated until the 1970s. Before that, drainage was the natural enemy. The different approaches needed by upper landowners and those at the bottom of the hill didn’t get much thought.
Those at higher elevations are responsible for their own drainage but can’t do it in a way that hurts property owners at the bottom of the hill. Similarly, the landowner at the base of the incline can’t back up the system. They live at the mercy of gravity.
“The bottom of the hill is generally a lake or a closed basin,” Cahoon said. “So, you’re going to receive that water from the upper landowner and there isn’t a whole lot you can do. In the development of our property that’s where it gets very complex.”
Looking back through old Democrat photos, it’s clear that flooding used to be a city-wide nuisance. There were the usual suspects: Franklin Boulevard, Lake Ella breaching its banks and the South Monroe corridor.
Cahoon recalled ferrying people by boat out of the neighborhoods on the South Side and Killearn. Tennessee and Monroe streets and Apalachee Parkway used to flood easily with downpours of two inches.
Franklin Boulevard was prone to flood with the slightest rains. In May 1974, two 13-year-olds – Joe Kirvin and Roger Elliot – drowned after being sucked under the swirling waters overflowing Franklin Boulevard’s ditch.
Former City Commissioner Dot Inman-Johnson recalled people in Lafayette Oaks, wedged between Miccosukee Road and Mahan Drive, being rescued in boats following heavy rains.
She recalls Trestott Drive in Betton Hills flooding when McCord Park Pond rose over its banks; Lake Elberta in the Bond Community and Frenchtown flooded pretty much any time several inches of rain fell.
Leon High School’s lower parking lot, dubbed “The Bowl,” used to flood regularly before the Franklin Boulevard project was completed.
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A stormwater pioneer's 'enormous task'
In 1987, Tallahassee became the first Florida city to form a public stormwater utility system.
Inman-Johnson, who served on the Tallahassee City Commission from 1986 to 1994, recalled just why that happened.
“It was because we had big portions of Tallahassee and some areas of the county that were floating away,” said Inman-Johnson, who is now an author and radio show host.
She said the county and city had different levels of maintenance and as the city grew along with the proliferation of non-absorbent concrete, the burden shifted to the city.
The city purchased homes along McCord Park pond that flooded, moved the residents and turned their properties into part of the drainage mitigation system. Cascades Park is one of the city’s top recreational attractions and the centerpiece of stormwater management downtown.
Since the stormwater utility was created 31 years ago, more than $200 million in water mitigation projects have been completed, half of that in the past 10 years. With the monthly $8.18 stormwater fee paid by each residential household within the city, new projects continue to crop up, old pipes and drains are retrofitted and the water continues to come.
“We have special needs here in Tallahassee,” Cahoon said. “We’ve developed something very special.”
►See Leon County's drainage basins map
Right now, there is work being done on a Kissimmee Street drainage ditch.
The $5.13 million project connects drainage points from Florida State and Florida A&M universities’ campuses south to Orange Avenue to the Munson Slough system, one of three main basins for rainfall.
Lakes Jackson and Lafayette are the other two main basins.
“If you think about the pipes we’ve got to maintain, operate and keep functioning, it’s an enormous task,” Cahoon said. “We inherited a lot of problems. It’s one of the reasons we started our stormwater utility.”
The city is responsible for maintaining drainage on 28 percent of Leon County. The county is responsible for about 27 percent and the rest is divvied up between private owners and the state and federal governments. Roads in unincorporated parts of the county, state universities and Interstate 10 are all maintained by different entities.
Inman-Johnson remembers the $1 stormwater fee that came with the first year of the new utility’s implementation.
“We had a real bad problem back then that wasn’t being solved and there wasn’t money to do it without a stormwater fee,” she said, noting that in three decades that fee has only risen by $7. “It seems a small price to pay in order to make sure we maintain a high quality of life and safety. That stormwater utility has taken care of some huge problems for Tallahassee that would have only gotten bigger.”
An uphill – and downhill – battle
The city requires all new homes to be built 2 feet above the base flood level. It’s an effort to get developers to build more responsibly with drainage on the forefront.
The system is designed to handle a 25-year flood. That means there is a 4 percent chance that there will be a flood. The system can handle 99.7 percent of the possible rain events based on 30 years of data.
The Department of Transportation by contrast, which maintains the major thoroughfares through town – Apalachee Parkway, Monroe and Tennessee streets and Thomasville Road – builds its drainage system to a 3-year flood spec. There’s a 33 percent chance the system will become overwhelmed in any given year.
Does that mean that the entirety of the system can handle that amount of water? Nope. A lot of it was built decades ago to different standards.
Despite the city designing and building its own curb inlets with four times the capacity of a standard one on DOT roads, the goal isn’t always passable roadways, Cahoon said.
“The primary objective isn’t to get water out of the streets. It’s to get water out of those homes,” Cahoon said. “Flooding on roadways is very temporary in nature and the damage generally is not as catastrophic. Flooding of buildings is something we’ve focused our resources and time on.”
But on certain days during certain months, there is going to be flooding in certain places.
On July 24, Leon’s parking lot flooded. School District officials say it’s the first time the lower bowl, which sits at the bottom of the hill and is home to parking and athletic fields, filled with rainwater since the completion of Franklin Boulevard.
Leon’s parking lot is built in a low-lying basin that was a wetland in a past life. Manmade changes to the area haven’t caused more flooding, Cahoon said, but they can help to alleviate them.
Still, there is only so much that can be done there and throughout the city.
“It’s always going to be flood-prone,” he said. “Anything that has flooded has the potential to flood again. You can’t design to where it will never flood, but we can reduce the probability.”
Contact Karl Etters at firstname.lastname@example.org or @KarlEtters on Twitter.
The rainiest cities in the U.S. ranked
1. Mobile, Alabama
2. Pensacola, Florida
3. New Orleans, Louisiana
4. West Palm Beach, Florida
5. Lafayette, Louisiana
6. Baton Rouge, Louisiana
7. Miami, Florida
8. Port Arthur, Texas
9. Tallahassee, Florida
10. Lake Charles, Louisiana
- Tallahassee’s average rainfall- 59 inches
- Most rain in a single calendar day- 8.83 inches on Sept. 21, 1969 at the Tallahassee Regional Airport.
- Most rain in a 24-hour period- 10.13 inches on June 11-12 during Tropical Storm Allison
- The city of Tallahassee maintains:
- 28 percent of the county’s roadways
- 432 stormwater ponds
- 412 miles of enclosed, underground storm drain pipes
- 224 miles of roadside ditch
- 80 miles of medium and large outfall ditches
Leon County maintains:
- 261 stormwater ponds
- 29.5 miles of enclosed storm drains
- 650 miles of roadside ditches
- 54 miles of medium to large outfall ditches
- 6.2 miles of major outfall ditches