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Water Quality In Old Tampa Bay Continues To Deteriorate

bridge over water with algae bloom near it
Courtesy Southwest Florida Water Management District
Algae bloom in Old Tampa Bay, north of Howard Frankland Bridge, August 2011.

It's partly attributed to cars on the numerous bridges in the area that are helping to feed algae blooms.

A new study shows most of the water flowing in one part of Tampa Bay is getting murkier.

For the sixth straight year, the Tampa Bay Estuary Program report shows water quality in Old Tampa Bay is deteriorating.

That northwestern portion of the bay is being hurt by the causeway bridges that connect Tampa and Pinellas County.

The Howard Frankland, Bayside and Gandy Bridges and the Courtney Campbell Causeway are blocking water that flushes in and out of the bay, and emissions from cars are blowing into the bay as nutrients, feeding algae blooms.

Map of chlorophyll in Tampa Bay
Tampa Bay Estuary Program
The red dots show high chlorophyll levels in Old Tampa Bay

Maya Burke is the program's assistant director. She says too many nutrients in the water — such as chlorophyll — keeps sunlight from penetrating to the bay bottom, killing seagrasses vital for fish and marine life.

"We really have a lot of complex issues that are coming together for Old Tampa Bay that's making it really challenging for bay managers to see the kind of successes there that we see elsewhere in Tampa Bay," she said.

To address the problems, they are been working with state transportation planners to extend the elevated portion of the newest span of the Howard Frankland, and build more bridges along the causeway.

"We hold out hope that the Howard Frankland Bridge can also be extended," Burke said, "so that we can hopefully release some of the water that's circling in that Feather Sound area of Old Tampa Bay."

Those successes she mentions are being seen in the rest of Tampa Bay, which travels south to Anna Maria Island in Manatee County. Nutrient levels there continue to be stable or lowering.

This a big rebound from the days when massive fish kills were reported from untreated wastewater being dumped into the waters. But Burke says they have to continue to be vigilant.

"We still do have wastewater point-source discharges," she said. "We also have stormwater discharges from those large flood control structures that are delivering stormwater nutrients, things like that, as well."

Steve Newborn is a WUSF reporter and producer at WUSF covering environmental issues and politics in the Tampa Bay area.