Experts in environmental engineering and natural resource management came together Saturday to present new information on the high phosphorus levels in southern Cayuga lake, a growing a source of controversy in the Ithaca area.

The panel discussion at Unitarian Church Annex in downtown Ithaca, organized by nonprofit group Cayuga Lake Watershed Network, drew a small but enthusiastic crowd.

The level of phosphorus in Cayuga Lake has generated concern ever since the New York State Department of En­viron­mental Conservation issued a report last year that listed Cayuga’s southern end as an “impaired segment,” citing high levels of sediment, phosphorus, and bacteria. While Cornell’s lake source cooling system has come under fire recently as a possible source of the high phosphorus levels, the panelists all agreed that many factors contribute to the high levels and that lake source cooling does not significantly impact Cayuga’s phosphorus content.

Although phosphorus level in Cayuga is high, its negative impact is unclear, according to the scientists on the panel. The speakers agreed that the high phosphorus level in the southern end of Cayuga — which had been a marsh until the late 1800s — might not be entirely unnatural or even unhealthy for the lake. The panelists also said that high phosphorus levels have been detected in the other Finger Lakes as well. The phosphorus content is only one of many ecological issues facing Cayuga; other threats include the encroachment of invasive species that outcompete native organisms in the lake.Is this algae?: What appears to be algae on Lake Cayuga may be “a diverse community of macrophys,” according to Prof. Todd Cowen, civil and environmental engineering.

“There’s a lot of new information we wanted to bring out,” said John Mawdsley, the Chair of the Cayuga Lake Watershed Network. He cited the many misconceptions about Lake Source Cooling as just one reason why it is important for his organization to improve public knowledge about issues affecting the lake.

Prof. Ruth Richardson, civil and environmental engineering, who also chairs the Watershed Network’s issues committee, agreed with Mawdsley, adding that it is “perfect timing” for a discussion of this kind to take place because of the recent controversy surrounding lake source cooling.

The morning’s program was divided into four talks given by different speakers and a panel discussion at the end. The focus was on measuring and modeling inputs into Cayuga Lake. “We wanted to get a handle on what was coming in [to the lake]” said Mawdsley, adding that measuring and modeling are “both valuable tools” which help the scientists understand the situation and possible solutions to improve water quality.

The issue of trying to measure and model a problem with many of possible contributing factors was a central theme in all presentations.

Two organizations that have been testing the water quality of Cayuga’s feeder streams presented different data sets. Their representatives — Roxy Johnson, the City of Ithaca watershed coordinator, and Steve Penningroth, the executive director of the Community Science Institute, another local non-profit that works closely with the Watershed Network and the City of Ithaca — agreed that while certain tributaries did contain a high level of phosphorus, the data they presented differed due to their varying measuring strategies and the difficulty of doing sampling in the field.

Prof. Doug Haith, biological and environmental engineering, presented a model he had created of the possible sources for Cayuga’s phosphorus.

“We have a fair amount of data on what goes on in the lake … what we don’t know is what’s going into the lake,” Haith said, describing his reason for conducting the modeling study.

Haith and his team divided the land surrounding Cayuga into categories such as forested, agricultural and urban. He found that much of Cayuga’s phosphorus comes from runoff, but also stressed that developing a model is difficult because of the “high degree of variability” in phosphorus input from year to year.

Prof. Todd Walter, biological and environmental engineering, highlighted many of the same points as Haith. However, Walter focused on possible solutions to the phosphorus problem, citing many agricultural initiatives that could cut off phosphorus runoff, such as keeping livestock away from feeder streams.

The panelists agreed that there are often more questions than answers in the study of Cayuga, but most are optimistic about the future of modeling and measuring effects on the lake.