ITHACA, July 26, 2021 — Cayuga Lake is the No. 1 hot spot in New York for harmful algal blooms (HABs), according to the latest Department of Environmental Conservation map that tracks outbreaks statewide.
As of Friday, Cayuga had more than two dozen cyanobacteria blooms, while neighboring lakes Seneca and Owasco had yet to report their first.
HABs, which look like algae but are actually toxic bacteria, tend to intensify in the late summer and early fall. In recent years they have become a menace in August and September, forcing dozens of Finger Lakes beach closings.
Cayuga had its first suspicious bloom June 10 and its first confirmed cyanobacteria bloom June 30, according to the Community Science Institute in Ithaca.
Most of the early blooms were reported toward the northern end of the lake and were composed of the cyanobacteria dolichospermum and microcystis. By mid-July most bloom activity had shifted to the southern end.
The most toxic bloom was observed on July 10 in a cove in the Village of Cayuga that registered roughly 4,400 times the state limit for cyanotoxins in drinking water. Tests for toxicity levels are pending for most of the other blooms reported by CSI. The DEC uses the CSI reports to update its statewide map.
Last year Cayuga Lake had far more HABs than Seneca Lake for reasons that weren’t entirely clear, even to seasoned observers.
The DEC’s latest response to Cayuga’s intensifying HABs crisis is a draft plan to reduce phosphorus in the lake by 30 percent — under federal rules for total maximum daily load, or TMDL.
“The measure proposed today to significantly reduce Cayuga watershed’s phosphorus loads will be instrumental to safeguarding the long-term health of the lake and helping prevent water quality impairments like harmful algal blooms, excessive weed growth, and turbidity,” DEC Commissioner Basil Seggos said in April.
But the initiative has been widely panned by the Cayuga Lake Watershed Network, CSI, independent scientists, the non-profit law group Earthjustice and state Assemblymember Anna Kelles (D-Ithaca), among others.
The agency accepted public comments on the draft plan through July 8, and many responses were harshly negative.
Critics accused the DEC of relying on stale data and leaping to the unwarranted assumption that large dairy farms do not contribute phosphorus to the lake.
The draft TMDL states that under the most widely-used DEC permit for large dairies, or CAFOs (concentrated animal feeding operations), “no discharge of process water is permitted, and nutrients applied to the landscape are done so at agronomic rates. Therefore, discharge from CAFOs (into Cayuga Lake) is assumed to be zero.”
Earthjustice called that assumption “both legally and factually false.”
The draft TMDL identified 33 medium and large CAFOs in the Cayuga Lake watershed, all of them covered by the more lenient of two types of DEC farming permits.
Until 2018, more than half of those CAFOs had held permits that allowed them to discharge waste. But after Albany County Supreme Court Judge ordered greater regulatory scrutiny of the discharge permits, 17 Cayuga watershed farms (and 200 statewide) abruptly switched to the more lenient permit by claiming they no longer discharged at all.
Not everyone has shared the DEC’s presumption that each of those permit conversions was legitimate. “There must be real data on the impacts of these (CAFOs), not adherence to a statutory fiction that presumes zero pollution,” Kelles wrote in her comment letter.
Kelles went on to say that the draft TMDL is “wholly lacking in offering specific legislative, regulatory and budgetary goals that would enhance water quality of the region.”
In its draft TMDL, the DEC divides the lake into four segments and states that only the extreme southern end is “impaired.” Focus on the southern tip is based on the conclusion that it alone failed to meet federal water quality standards in 2002.
The agency’s prescription for fixing that impairment is to cut the lake’s total phosphorus load by 30 percent. To build its case on how and where to cut phosphorus inputs, it relies on data collected from 1998 through 2013 — before HABs became a widely acknowledged problem in 2015 and 2016.
In late 2017, Gov. Andrew Cuomo announced a $65 million statewide HABs initiative that identified Cayuga Lake as a target waterbody and ordered an action plan for it.
“HABs occurrence has been linked to phosphorus and other nutrient inputs and is exacerbated by heavy rain events and warming waters related to climate change,” Cuomo said at the time.
While the draft TMDL focuses on reducing phosphorus, it all but ignores the “other nutrients” and any impact from climate change.
The Cayuga Lake Watershed Network, among others, argued that the draft TMDL needs updating to recognize the climate change effects of rising temperatures, heavier rainfall and stronger storms because they will boost both phosphorus levels and cyanobacteria blooms.
More intense rains will speed eutrophication of the lake, especially at the northern end, as heavier runoff from CAFO manure spreading will add phosphorus to the lake, Earthjustice wrote on behalf of the group Seneca Lake Guardian.
Several commenters faulted the TMDL study for relying on phosphorus data collected from the middle of the lake rather than from shorelines, where readings tend to be far higher and weeds and toxic algae abound.
And its reliance on average summertime readings fails to capture phosphorus spikes in the winter due to CAFO runoff from manure spreading on frozen fields, they said.
Cornell scientists Robert Howarth and Roxanne Marino argue in a joint comment that the draft TMDL does not adequately address the most dire water quality threat to the lake — cyanobacteria blooms.
“We believe these toxic blooms pose a larger water quality threat to Cayuga Lake than did the original phosphorus impairment,” Howarth and Marino said. “Phosphorus is probably not the prime cause of the blooms … and importantly, phosphorus is probably not the factor controlling the toxicity of blooms.”
Howarth, Marino and Kelles agreed the TMDL study must explain how nitrogen interacts with phosphorus to fuel toxic blooms.
Stephen Penningroth of CSI wrote that the total phosphorus level cited in the draft TMDL is a “statistical outlier” — nearly double the average of findings of three independent sources. He asked the DEC if it would “delist Cayuga Lake for phosphorus” noncompliance if further evidence showed that the consensus number proved to be more accurate than the draft TMDL.
Several other commenters said the study does not adequately address who will supervise corrective action or how it will be paid for. They called for the draft to be thoroughly rewritten or withdrawn entirely.
The DEC declined to respond to specific negative comments and instead issued the following statement to WaterFront:
“DEC received comments from a wide variety of stakeholders and is now carefully reviewing these comments and revision requests submitted during the public comment period. DEC’s response to comments will be made available on our website, along with the final version of the TMDL.”