By Marcia Biggs
This is part of a series of stories called “Elephant Bites,” that looks at innovative designs local governments and developers are using to capture nutrients before they enter surface waters. Learn more here.
SAFETY HARBOR — One can hardly find a more cerebral place on Tampa Bay than Safety Harbor.
Here along the upper northwest shore of Old Tampa Bay, mangroves create refuges for a variety of shorebirds and other marine creatures. Pelicans fly above the pier where fishermen cast lines and nets in search of snook, mullet and redfish, while dolphins and manatee frolic nearby. Along a paved trail that hugs the shoreline, bicyclists and runners enjoy a scenic view of the bay and the calm, shallow waters are favorites for kayakers and paddle boarders.
But beneath the surface, trouble is looming. Testing has found the water quality here lags behind the rest of Tampa Bay. In this watershed area, Mullet Creek, Alligator Lake and the Lake Tarpon overflow canal drain directly into the bay, bringing nitrogen-laden runoff from the surrounding communities. A series of large algae blooms have plagued Old Tampa Bay in recent summers, and Tampa Bay Estuary Program is conducting a comprehensive, large-scale research effort to identify causes and potential remedies.
According to TBEP scientists, more than half the nitrogen entering Tampa Bay comes from stormwater runoff from urban and residential areas. Stormwater, the water that runs off the land with rainfall, carries with it fertilizer and pesticide residues, as well as trash. Excess nitrogen accelerates algae growth, limiting the amount of sunlight reaching seagrasses and hindering a healthy marine ecosystem. Research has linked a build-up of thick, noxious muck in Old Tampa Bay near Safety Harbor to stormwater runoff high in nitrogen.
“It’s actually a combination of nutrient pollution and poor circulation that is driving the muck problem,” says TBEP Senior Scientist Ed Sherwood. “We’re looking at various models that would improve circulation, but preventing further stormwater inputs into that area will certainly add to the future health of that area of the bay.”
Preserving the environmentally sensitive land that makes Safety Harbor unique is a priority for city officials. But for years, winding Bayshore Boulevard south of Safety Harbor Spa has been a source of concern. Summer rains combined with poor drainage caused constant pooling and pollution runoff into the bay. The flat geography was the main culprit, according to Ray Boler, Safety Harbor’s director of public works.
“Pools of stormwater would collect on the west side of the street, wash across the asphalt and drain into the bay,” he explained. “During extreme high tides, water from the bay might even reach the street, drawing pollution, trash and oak leaves back down with it.”
In 2010, the city won grant funding for a $2.6 million project that would alleviate pollution from stormwater runoff by improving drainage along South Bayshore Boulevard. With $1.3 million from the FDEP and $800,000 from Southwest Florida Water Management District, the city committed another $96,000. The Safety Harbor Stormwater Improvement Plan would include roadway and sidewalk improvements, including replacing the Bayshore sidewalk trail and sewer lines. Even though the sewers had not reached a state of advanced deterioration, replacing them now would preclude the need to excavate the roadway at a future date, said Boler.
Since the land is flat, a swale had to be formed between the street and the trail sidewalk by realigning and raising the elevation of the sidewalk and raising the elevation of the street. Safety Harbor hired Cardno TBE of Clearwater to design a project that would pipe stormwater under Bayshore and into large concrete baffle boxes which remove trash and sediment before entering the swale. The 5,000-linear-foot swale is large enough to remove over 7,300 pounds of pollution from the stormwater runoff each year.
The eight baffle boxes, which range in size from 5x11 feet to 10x16 feet, are situated at various locations along South Bayshore where they will remove suspended solids as the water flows through a series of chambers and filters. The filtered stormwater then flows through channels into the bay. City crews will be responsible for vacuuming the contents of the baffle boxes and cleaning the filters annually, Boler added.
Construction started in September 2011 with an initial completion date of June 2012, but a series of delays kept pushing back the completion date. Finally in March, the final stages were completed with the addition of three landscaped traffic islands in the middle of South Bayshore for beautification.
Even before the Safety Harbor stormwater project was complete, good news arrived. TBEP’s 2012 Water Quality Report released in February shows marked improvement in Old Tampa Bay since 2011. Water quality standards jumped from the red designation (inadequate to support seagrass) to green (meeting water quality targets to support seagrass). In fact, all segments of the bay met water quality targets in 2012, for only the fourth time since baywide assessments began in 1974.
“This is an impressive testament to the collective efforts of both local governments and private industries to reduce pollution in the bay, especially when you consider that the population around the bay has grown by more than 1 million people since 1974,” said Holly Greening, TBEP executive director. “Tampa Bay is one of the few estuaries in the nation that is showing this kind of sustained improvement.”
Marcia Biggs is a freelance writer who lives in Safety Harbor.