A recent study by researchers from the Indiana University School of Public and Environmental Affairs found algal toxins in Indiana lakes at levels elevated above the national average. The survey found detectable levels of microcystin in 68 percent of Indiana lakes and reservoirs sampled.
IU's SPEA team was lead by professor Bill Jones, who tells NUVO that the national Environmental Protection Agency office contacted him to sample Indiana lakes as part of their ongoing National Lakes Assessment. The national survey found microcystin in only 32 percent of lakes and reservoirs, less than half the amount of Indiana lakes with the toxin.
Microcystin is a toxin produced by cyanobacteria, or blue-green algae, and has been linked to animal deaths and fish kills. For humans, if water with microcystin is ingested, gastro-intestinal discomfort and nausea may ensue. Coming into contact with the toxin can produce skin irritation. EPA's National Lakes Assessment refers to microcystin as a "potent liver toxin." When blooms of high concentration occur, "they resemble bright green paint that has been spilled in the water."
Eagle Creek, Geist and Morse reservoirs have received attention in recent years in relation to the problem as public health advisories have been issued. Although the issue of algal toxins is becoming better recognized, the state of Indiana still lacks a statewide monitoring and public information plan.
The lack of a monitoring program is something that IUPUI professor Lenore Tedesco sought to rectify in recently speaking to the State Legislature's Environmental Quality Service Council about the occurrence of blue-green algae and how other states deal with it. The council then made recommendations to the Indiana Department of Environmental Management for future action.
According to IU's Jones, the National Lakes Assessment is the first time that Indiana bodies of water have been sampled for microcystin. Each state has different water quality standards and data collection procedures; the national assessment was an effort for a much needed comprehensive report on the health of the nation's lakes.
Jones, who heads the Indiana Clean Lakes Program, says that in spite of the alarming number of lakes with the toxin, its concentration in lakes is relatively low. The World Health Organization guideline value for drinking water is 1 microgram per liter, a level only achieved by eight of the Indiana lakes sampled with detectable microcystin. Jones went on to say that many states do not issue a public advisory until a level of 6 micrograms per liter, a level achieved by no Indiana lake sampled in the survey.
But the sampling procedure could alter documented levels of microcystin according to Jones. The IU team took samples from the middle of the lake, however, "more algal growth tends to appear near the shore in the warmer water, so levels can be variable," says Jones.
While microcystin in the water is cause for concern, most feel that it does not appear to be a major, immediate health threat at present levels. What the prevalence of microcystin indicates to Jones is that many of the waterways in the state suffer from over nutrification. "There is too much phosphorus and nitrogen," Jones says. These nutrients often come from agricultural sites, but a significant contributor seems to be residential lawn fertilizer.
As Rae Schnapp, Riverkeeper for the Wabash, explains, "phosphorus is the limiting nutrient in most aquatic systems." The limiting nutrient is the nutrient that will be exhausted first and therefore limits growth- in this case algal- in relation to its availability. When excess phosphorous is introduced into an aquatic system plants and algae will grow strongly. "We have to reduce the phosphorus load, it comes down to using less fertilizer," Schnapp says.
Jones points out that Minnesota, Wisconsin and select counties in Michigan have all passed bans on the use of residential lawn fertilizers with phosphorus. Their soils, like Indiana's, naturally have sufficient amounts of phosphorus to grow robust grass not in need of being supplemented.
It appears that fertilizer bans have been effective in lowering total phosphorus found in waterways, Jones points out from a study done by the University of Michigan which found significantly reduced nutrient levels after the implementation of a municipal lawn fertilizer ordinance.
Schnapp feels that a partial ban on phosphorus fertilizer could be extremely beneficial to the environmental health of the state, although this was not a course of action recommended by Tedesco when she spoke to the legislature. The legislative council chaired by State Senator Beverly Gard did not examine the causes of out of control algal growth according to Tedesco, although the council has decided to study the algal toxin problem more.
The implementation of a formal mechanism for reporting microcystin levels would fall to the Indiana Department of Environmental Management. Amber Finklestein at IDEM says that they are taking the problem very seriously and are looking to
"partner with other agencies and groups to expand the range of testing in the state." In order to do this IDEM has to look for a funding source for expanded lake monitoring and decide which lakes in the state need the most attention.
Where to go from here
While the state works out ways to monitor microcystin levels and keep the public informed, Jones feels there are two ways to approach the problem of over nutrified lakes. "The proper approach," as he calls it is to cut off the supply of nutrients which have built up in soils and streambeds for years. He says it will take decades to exhaust the surplus fertilizer from our soil systems. "Everyone wants a quick fix, but the problems of our lakes today have taken decades to build up, and will probably take decades more to fix."
The other solution is to treat waterways with algaecides which are not preventative and often do not solve the problem. Tedesco states that using algaecide is not advisable in cases when a toxin producing species is present, it may critically lower the oxygen level of the water.
Both Jones and Tedesco agree that reducing nutrient input to waterways is critical. Tedesco says that "the state of Indiana is a huge exporter of nitrogen to the Gulf of Mexico, in addition to adding nutrients to local water systems." She says that major producers of phosphorus are wastewater treatment plants, and a way to possibly reduce the phosphorus load would be to make permits stricter.
Jones and Tedesco also both noted the actions of Steuben County, Indiana which has banned phosphorus to prevent over nutrification. Other creative solutions that some have proposed include mixing the water column and installing floating mats of plants to absorb excess nutrients. Jones and Tedesco state that these solutions have not been proven to be effective on a large scale.
To learn more about the National Lakes Assessment visit www.epa.gov/owow/lakes/lakessurvey/. To read more about Indiana's own Clean Lakes Program go to www.indiana.edu/~clp/.