he return of rain in 2003 was good news for many in North Florida, filling wells, watering crops and returning rivers to historical levels after five-plus years of below-normal rainfall.

But the extra water brought with it an unexpected and unwelcome visitor, Suwannee River Water Management District officials said Thursday.

Nitrates.

Above average rainfall and human activity in the Suwannee River Basin combined to contribute nearly 4,500 tons of nitrate-nitrogen to the Gulf of Mexico between October 2002 and September 2003, a 50 percent increase in deposition of the habitat-altering nutrient from the previous year, officials said.

Nitrates continued to be a problem in groundwater and springs as well, the report found, with Floridan Aquifer water in the Middle Suwannee River Watershed - which covers much of Suwannee and Lafayette counties - exceeding the federal government's drinking water standards in some locations.

The Middle Suwannee, home to about 40 dairy farms, contributed much of the river's nutrient load - about 1,541 tons, or 34 percent - the report found.

David Hornsby, a district water quality analyst, attributed the jump to increased rainfall. On average, rainfall for 2003 in the Suwannee River basin was 1 inch higher than during each of the five previous years, leading to an increase in stream flow.

Simply put, Hornsby said, more rain during the year meant more water to transport nitrates downstream.

"It is strictly related to the amount of water that went down the river," Hornsby said.

An essential nutrient for plant growth, nitrates leached from human or animal wastes can severely alter aquatic habitats.

When concentrations climb too high, algae and other non-native plants can push out native species, robbing them of oxygen and in turn, killing off habitats preferred by fish and other aquatic life.

The negative impacts can extend far beyond the health of a few trout.

As nitrates from dairy and chicken farms, septic tanks or golf courses build up in the groundwater, once-clear tourist attractions such as the spring-fed Ichetucknee River can slowly choke as algae and other plants grow out of control.

The result, some state economists fear, could be the loss of millions of dollars in tourist-related revenue as visitors avoid slimy-green waters.

Elevated nitrates in potable water also can pose significant health risks, including causing in humans shortness of breath, hemorrhaging of the spleen and even death.

To guard against contamination, the U.S. Environmental Protection Agency has set a nitrate-nitrogen threshold of 10 parts per million for public drinking water supplies.

Three samples tested by the Water Management District exceeded the EPA standard, the report found. Springs in the Middle Suwannee Watershed - one of the state's most impacted areas for groundwater nitrate contamination, the report said - have nitrate-nitrogen concentrations ranging from 1.2 ppm to 17 ppm.

Water quality experts estimate spring health suffers when nitrate-nitrogen is present at concentrations as low as 1 ppm.

Some say the region's elevated nutrient levels are proof more needs to be done to control the ecological threat. While few dispute the science of this year's water quality update, agreeing that increased rainfall equals more nutrients downstream, nitrate levels are unlikely to decline without help, they say.

"There is a big problem, we know that," said Linda Young, southeast regional coordinator of the Clean Water Network in Tallahassee.

"But making excuses and trying to sweep it under the carpet is not going to solve the problem," she said.

For years, environmental advocates such as Young have pointed to pollution from dairy and chicken farms as the primary source of nitrates in the river and surrounding springs. They point to state data showing that the number of dairy cows in the Middle Suwannee has climbed since 1998, while totals in other Florida farming regions have dropped.

In March, a state judge appeared to agree, ruling in favor of Young and three state environmental groups who had charged that the Florida Department of Environmental Protection needed to do more to regulate the waste generated by the state's largest dairy operations.

Attempts by farm county lawmakers to supersede the court ruling and exempt most state dairy farms from water pollution regulations failed last month.

Still, the man who runs the Suwannee River Water Management District said programs are in place to see a decline in nitrates over the years.

"Common sense tells you, you are not going to make a significant change (in nitrate levels) in one or two years," Jerry Scarborough, executive director of the Suwannee River Water Management District, said in a recent interview.

Through cooperative programs and voluntary measures such as the Suwannee River Partnership - a group of scientists, farmers and regulators dedicated to reducing agricultural pollution - "we feel that the nitrate levels are going to go down," Scarborough said.

"But it's not going to happen overnight."

Greg Bruno can be reached at (352) 374-5026 or greg.bruno@gvillesun.com.