Water quality in Old Tampa Bay slipped a bit this past year, but water in the rest of the bay continued to show signs of improvement, according to a report released this week by the Tampa Bay Estuary Program.
Every year the Tampa Bay Estuary Program assesses how clean the water in the bay is by checking the amount of microscopic chlorophyll floating in the water and measuring how well sunlight penetrates past the surface.
The estuary program's scientists check the water quality in the four sections of the bay — Old Tampa Bay, Hillsborough Bay, Middle Tampa Bay and Lower Tampa Bay — to see whether the water will be clean enough to promote the natural recovery of underwater sea grasses.
Sea grasses are crucial to the health of the bay, but they declined sharply and by 1982 there were only 22,000 acres left.
Since then the bay regained 6,000 acres. By 2006 there were 28,299 acres. (The bay gained about 1,300 acres of that just from 2004 to 2006.)
Although that was far less than the estuary program's goal of 38,000 acres, it marked a milestone: the most sea grass in the bay since the 1950s.
Sea grass growth is limited by pollution. In 2006, for the first time since water quality monitoring began in 1975, every corner of the bay came out as clean.
But last year, the estuary program found, the quality declined in some portions of Old Tampa Bay, which encompasses the part of the bay north of Weedon Island and the Interbay Peninsula.
"Old Tampa Bay has been a problem area for us over the last few years," said Nanette O'Hara, spokeswoman for the estuary program.
The area suffers from what estuary program scientist Ed Sherwood called "urban slobber" — polluted runoff from fertilized lawns and a multitude of other sources on the developed shoreline.
"There's not one smoking gun in that area," he said.
One of many culprits: Largo's wastewater treatment system runs its treated effluent through a golf course's mangroves into Old Tampa Bay, he said. That's something to work on cleaning up in the future, he said.
The cleanest water in the bay is the area closest to the mouth, O'Hara said, because it is regularly flushed with water coming in from the Gulf of Mexico.
Craig Pittman can be reached at email@example.com or (727) 893-8530.