Water clarity, as indicated by chlorophyll a concentrations, remains as good as or better than it was in the benchmark 1950s period, thanks to improved wastewater and stormwater treatment, reductions in industrial discharges, limits on dredging and filling, and removal of several wastewater point sources as extensive water reuse systems are constructed.
Stormwater associated largely with urban and residential runoff remains the largest source of nitrogen, the primary pollutant in the bay. An overabundance of nitrogen can cause algae blooms and reduced oxygen levels in the bay, resulting in turbid water, fish kills and loss of seagrass when the water becomes so cloudy that sunlight cannot reach grass blades. Stormwater accounted for 63 % of total nitrogen loadings to Tampa Bay from 1999-2003.
The Tampa Bay Estuary Program's Policy Board, along with TBEP's Nitrogen Management Consortium -- a partnership of local governments and private industries with facilities along the bay -- has adopted a goal of maintaining nitrogen loadings to the bay at the average calculated for the 1992-1994 timeframe. This "hold the line" approach is expected to foster water quality sufficient to allow continued natural recovery of seagrasses. However, achieving this goal with the continued growth and associated increases in stormwater runoff projected in the region will require baywide loadings to be reduced by 17 tons per year. Local governments have committed to assuming a reduction target of 11 tons per year, while industry partners have agreed to reduce their contributions by 7 tons per year.
As of 2004, projects completed in the Tampa Bay watershed by NMC partners actually exceeded those reduction goals. Additionally, all major bay segments except Old Tampa Bay met chlorophyll a targets (a measure of microscopic algae in the water) with the exception of El Nino years (1997-98 and 2003), providing sufficient water clarity for seagrass recovery. A separate seagrass recovery plan is being developed for Old Tampa Bay, to identify and remediate causes of continued water quality problems and seagrass declines there.
The bay narrowly averted a potentially devastating blow in 2001, when Mulberry Phosphates abandoned its Piney Point fertilizer plant and gypsum stack in northern Manatee County, forcing DEP to assume operation and cleanup of the facility. The threat of a potential breach in the gypsum stack holding ponds required DEP to discharge large volumes of nutrient-rich wastewater into Lower Tampa Bay, resulting in an additional 16 tons of nitrogen loading - more than three times the annual load reduction target for that bay segment. The crisis was alleviated in 2003, when DEP was granted an emergency permit to disperse treated wastewater from the site into the deeper waters of the Gulf of Mexico. Closure of the facility is well underway, but future use of the site remains undetermined. Cleanup costs had reached more than $77 million as of September 2005, prompting DEP to amend the rules pertaining to financial surety of phosphate companies operating in Florida to avoid a similar situation in the future.
A significant portion of the nitrogen entering the bay, about 21 %, comes from atmospheric deposition (air pollution) directly to the bay's surface, either with rainfall or dry deposition. Research indicates that power plants and mobile sources (such as cars) are the primary locally generated sources of airborne nitrogen. New pollution controls on bay area power plants and conversion of one major plant (Tampa Electric's Gannon facility) to fueling by natural gas instead of coal will result in dramatic reductions in nitrogen emissions from these facilities in the next decade. Cleaner-burning fuels, improved fuel economy standards, expanded mass transit systems and increased telecommuting could mitigate emission increases associated with motor vehicles.
Ensuring that bay waters remain safe for swimming and other recreational uses is vital to the region's tourist-dependent economy, as well as to the quality of life for area residents. Local health departments routinely monitor public beaches, and mandate closures when bacteria counts exceed guidelines. Closures occur most often when heavy rainfall funnels large volumes of stormwater runoff to waters near public beaches, or when a spill of partially treated wastewater occurs. Recent research has shown that the traditional indicators of bacterial contamination, E. coli and fecal coliform, may not be the most suitable barometers of contamination, since both may occur naturally in warm-water climates. As a result, the use of enterococci as a supplemental and more reliable indicator is now gaining widespread acceptance.
With the exception of several "hot spots" primarily near ports and other industrial areas, Tampa Bay sediments remain relatively free of toxic contaminants. Development of a Tampa Bay Benthic Index that assesses the severity of contamination at various sites based on lack of diversity or abundance of benthic (bottom-dwelling) organisms, low dissolved oxygen concentrations, or exceedances of contamination thresholds for heavy metals, PAHs and other toxics, will serve as the foundation for ranking sites where restoration is needed. Cleanup efforts may include dredging of contaminated areas or "capping" them with clean fill.
Using the Tampa Bay Benthic Index, TBEP's Sediment Quality Assessment Group has identified several sites where degraded benthic communities were clearly associated with chemical contaminants of concern. Priority areas identified by the group for development of site-specific action plans are the Palm River and McKay Bay; Ybor Channel; West Davis Islands; East Bay; Largo Inlet; the Westshore area of Tampa; Bayboro Harbor; and the Apollo Beach/Big Bend area. Assessment of each of these areas began in 2005, and action plans for two will be initiated in 2006.