Lake George Mirror
An assessment of shoreline algae, conducted by Rensselaer Polytechnic Institute and the Lake George Waterkeeper for the Jefferson Project, has generated some tentative, but nonetheless surprising, results.
“The surprise was that sites in the heavily developed south basin, where we expected to find evidence of higher fertility, were comparatively free of algae,” said Rick Relyea, the director of the Jefferson Project and a professor at Rensselaer.
The waters near Mohican Point, in Bolton Bay, yielded diametrically opposed results, despite the fact that operations at the Bolton Wastewater Treatment Plant have been adjusted to minimize the release of nutrients.
According to Waterkeeper Chris Navitsky, these findings can perhaps be explained by the fact that soils retain and release phosphates long after the source has been remediated.
“The flow of the tributary through Mohican Point has decreased by two thirds, but the concentrations of phosphates remains the same. That’s the legacy of fifty years of loading,” said Navitsky.
Relyea said the Jefferson Project’s Algae Survey is the first comprehensive survey of shallow-water algae in Lake George; it’s part of a larger effort to learn where excess nutrients pose the greatest threat to water quality and recreation.
“Many shoreline residents have told us they’ve seen an increase in algae in the shallow waters over the last two decades,” said Relyea. “Higher amounts of algae are associated with higher nutrients in the water, either from natural or human sources, so an increase in algae may signal in influx of nutrients into the lake. If that’s the case, Lake George will have to decide how it wishes to respond, but the first step is to acquire scientifically accurate information.”
To conduct the survey, Navitsky and RPI researcher Brian Mattes suspended small clay tiles from roughly fifty docks for eight weeks, enough time for the tiles to be colonized by algae.
Last week, they retrieved the tiles, weighed the amount of algae growing on them and replaced them with new tiles, which researchers will examine at the end of September.
According to Relyea, the Jefferson Project invited lakefront landowners to volunteer their docks for the study.
Of the seventy sites offered, fifty were selected, producing a data set comprising samples from a variety of locations distributed evenly along the length of the lake. Navitsky said the fact that samples come from those who volunteered their docks for the study may be at least partially responsible for the better than-expected results in the south basin.
“If you have concerns about your septic system and what’s growing near your shore, you might not volunteer to participate in this project. On the other hand, a family in the south basin who did volunteer has replaced its system, which could have been responsible for the near-shore’s water quality,” said Navitsky.
Now that the algae has been collected, it will be analyzed, its species identified and its sources traced to either nature or development.
“That’s the next step. Our goals also include discerning patterns to what we might call the hotspots; why are they located where they are, why are they not showing up in the south basin?” said Relyea. “This will help guide policy.”
A major goal of the study, said Relyea, is “to create the baseline for the future, which will allow us to see if near-shore water quality is improving.
We’ll repeat this study next summer, then not for another ten years.
We’ll see then how much, if anything, has changed,” said Relyea.
Relyea said samples will be collected three more times this year. Once the samples have been analyzed, the results will be posted online at the Jefferson Project’s website.