Coastal Services Center

As the pollution that can close shellfish beds coming from humans or animals? This question is important for coastal resource managers because in order to fix the problem, you must know the source, and if the source is a septic system, there may be additional bacteria or viruses that could make people sick.

A recent research study in Virginia has given the state's coastal managers a better tool for identifying the source of contamination in marine waters.

The study, "The Impact of Onsite Wastewater Systems on Water Quality in Coastal Regions," evaluated the use of a fluorometer in detecting human waste in an estuarine environment.

"We wanted two things" from the study, says Mark Slauter, coastal nonpoint coordinator for the Virginia Department of Conservation and Recreation. "We wanted a better way to identify impacts from septic systems, if there are any, and a more cost-effective and time-efficient manner in which to do it."

As a result of the research, coastal managers have modified the state's Shellfish Sanitation Program, and the state has been able to move forward on implementing its 6217 nonpoint source pollution program.

Managers say they believe the tool will also be useful in addressing the source of bacteria that can lead to beach closures, and in testing water coming out of storm drains to ensure there are no illegal sewer hookups.

The Glow of Success

While fluorometers have been used in freshwater environments in attempts to identify impacts from septic systems and to test drinking water, it was unknown if using the device in an estuarine system was feasible, or if it would be effective at detecting human sources of nonpoint pollution.

Charles Hagedorn, professor of environmental microbiology at Virginia Polytechnic Institute and State University at Blacksburg, explains that a fluorometer detects compounds that fluoresce under ultraviolet light, such as whitening agents in laundry detergents.

"If you walk under a black light," Hagedorn notes, it is these optical brighteners that "make your clothes glow in the dark."

Human sources of pollution, such as residues of fecal sterols, detergent surfactants, and optical brighteners in laundry and dish detergents, all can be detected by a fluorometer.

There are at least two major potential sources of contamination that could contain optical brighteners, Hagedorn says. These are leachates from improperly functioning septic systems and leaking pipes from community wastewater treatment systems.

System Failure?

Faulty septic systems may result when homeowners fail to maintain their system. "If you go knocking on doors and ask homeowners about the condition of their septic systems," Hagedorn says, "you will find too often that owners don't know where it is, don't know what type of system they have, or even if they have a septic system."

Many homeowners don't realize their system has a problem until leachate is visible in their yards. Hagedorn says that many septic systems, particularly in the Mid-Atlantic region, may have "subsurface failure," which is not easily detected because "many types of soils are so well drained it never perks to the surface."

The potential of septic systems leaching into areas with shellfish beds is a concern because of the possibility that harmful pathogens could be passed on to shellfish eaters.

Bob Croonenberghs, director of the Virginia Department of Health's Division of Shellfish Sanitation, says, "The problem with the shellfish program always has been trying to figure out the source of fecal coliform in shellfish-growing waters."

The division collects water samples and conducts bacterial source tracking, but this technology has its limitations.

"You are restricted in the number of samples you can take," Croonenberghs says, because the samples have to be taken to a lab for analysis, which is expensive, and getting the results can take days and even weeks. Also, using standard source tracking techniques, it is impossible to trace bacteria pollution back to a specific source.

"The beauty of the fluorometer," says Croonenberghs, "is that you get an instantaneous and continuous readout."

Testing, Testing

The dilemma for Virginia coastal managers was that "we didn't have a good handle on septic systems," says Mark Slauter. "We didn't know if there was a problem and, if so, what the extent of it was."

To find out its usefulness in helping to identify human sources of nonpoint source pollution, the fluorometer was tested in both the field and in the laboratory by Hagedorn and other researchers at Virginia Tech in partnership with the state Departments of Conservation and Recreation, Environmental Quality, and Health.

In all tests, the equipment correctly detected a human waste signature, Hagedorn says. "There was 100 percent agreement between using the fluorometer and using microbial source tracking methods to determine if the source was human in origin or not."

For control purposes, the field tests were conducted in areas already identified by bacterial source tracking techniques as having a human source. The fluorometer could detect high and low bacteria concentrations, and researchers were able to map sewage plumes in the water, which could be used to locate a specific source of contamination.

Confirmation

"I think what Dr. Hagedorn has shown us is that there is the potential for more of an impact [from septic systems] than we had really realized there may be," Croonenberghs says.

"The bottom line in all this is that the fluorometer is more efficient," Slauter says. "We are going to be able to more quickly determine areas where there are problems with septic tanks or sewer lines, and the Health Department can take samples then and there."

Since the study's completion last year, the state's Shellfish Sanitation Program has purchased two fluorometers for its field offices, which they plan to use to help detect small plumes of discharge from failing septic systems in shellfish-growing areas. They will use it to guide where they should take samples for routine monitoring, Croonenberghs says.

The Research Continues

Although the results so far "demonstrate that the fluorometric technique could be an inexpensive, fast, field methodology for detecting human-derived sources of bacteria pollution," Hagedorn believes more research is needed to confirm the initial findings and to study how algal blooms and oil-based products may affect the readings.

Still, coastal managers say they are pleased with the research so far.

"It's not often we get to answer a true research question that could have a drastic impact on how we address water quality issues," notes Slauter.

To read "The Impact of Onsite Wastewater Systems on Water Quality in Coastal Regions" final report, point your browser to www.dcr.state.va.us/sw/docs/czmfnlrep03.pdf. For more information, contact Mark Slauter at (804) 692-0839, or mslauter@dcr.state.va.us. You also may contact Charles Hagedorn at (540) 231-4895, or chagedor@vt.edu, or Bob Croonenberghs at (804) 864-7477, or bob.croonenberghs@vdh.virginia.gov.