Seneca Lake recorded 12 confirmed harmful algal blooms during the week ending Sept. 10 as reports increased around the lake, according to the latest water-quality update from the Seneca Lake Pure Waters Association.
The association said the blooms were scattered around the lake between Sept. 4 and Sept. 10. While activity has picked up during what the group describes as the prime season for HABs, the confirmed total remains below levels seen at the same point in recent years.
The update draws on data from the Finger Lakes Institute's real-time monitoring buoy, Pure Waters volunteers and the National Oceanic and Atmospheric Administration.
Rain lifts lake level
Recent rainfall helped the lake level rebound to 445.24 feet BCD on Sept. 11, the association reported. That reading put Seneca Lake slightly above its level at the same time last year.
Pure Waters said the additional water could help prevent the lake from reaching very low levels heading into late October. The group also noted that an ongoing gate leak is not expected to be repaired until at least November.
Surface water temperature measured 71.8 degrees at a depth of 3.3 feet on the evening of Sept. 10. Dissolved oxygen was measured at 107.5% in the top 30 feet.
Group backs Torrey data center pause
The weekly update also renewed Pure Waters' support for a local moratorium on large-scale data center development in the Town of Torrey as Greenidge Generation transitions toward artificial-intelligence data center infrastructure.
The association said a temporary pause would give the town time to evaluate potential effects on Seneca Lake and nearby communities. Its stated concerns include water use and discharge, heat entering the lake, air emissions, noise, energy demand and other possible environmental impacts.
Pure Waters directed readers to an online petition supporting the proposed moratorium. The update did not provide details about the length, scope or current legislative status of the proposal.
Volunteers sought for October regatta
Pure Waters is seeking four additional volunteers for the Seneca Monster Canoe and Kayak Regatta on Saturday, Oct. 3. The association is partnering with the event and needs help with registration, finish-line timing and boat spotting.
Volunteers will be needed between 9 a.m. and 1 p.m., with specific assignments and timing to be finalized closer to the regatta. The group is collecting interest through an online volunteer form.
The association also recapped its 2026 annual meeting and volunteer recognition program. More than 170 volunteers contributed time and expertise during the year, and the organization recognized Karen Welch, Jody Tyler and the Rose Family Foundation as its 2026 honorees.
What to watch for along the shore
Pure Waters urged residents and visitors to avoid water that may contain a bloom and to keep pets out. Possible HABs may resemble pea soup, spilled paint or surface scum, or appear as bright green or blue-green water, green streaks or swirling mats.
Blooms can collect along shorelines and in quiet coves, and conditions can change quickly. Anyone who sees a suspected bloom is asked to take clear photos, note the location, submit a report to the state Department of Environmental Conservation and email the images to senecahabs@senecalake.org.
The association also offers text alerts when possible harmful algal bloom conditions are reported on Seneca Lake.
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