Lake Winnipesaukee Cyanobacteria Update Sept. 5; Statewide Lakes Added
By Nancy West,
2024-09-05
Editor’s Note: The state Department of Environmental Services released the following update on cyanobacteria on Lake Winnipesaukee Thursday, the first update since Gov. Chris Sununu blasted the department last Friday for its messaging on cyanobacteria saying it needlessly scared people. See story here: https://indepthnh.org/2024/08/30/sununu-blasts-des-on-cyanobacteria-messaging-saying-it-does-not-kill-people/ But Thursday’s update didn’t include watches and warnings on other state lakes. InDepthNH.org added those to the story below from DES website.
The cyanobacteria warnings have been decreased to watches for Governor’s Island, The Broads, and Wolfeboro areas of Lake Winnipesaukee. The watches remain for the Alton and Tuftonboro areas. See map below.
Sampling performed September 4th revealed continued widespread but low densities of Gloeotrichia in all highlighted areas of Lake Winnipesaukee below. In addition to this, Gloeotrichia continued to be reported in these areas of the lake over the last week (reported August 27 – September 1), but fewer dense aggregations were observed over time. The watch status will be reevaluated and removed for all general areas in a week if no further cyanobacteria reports are received.
The map below shows the general names of the large sections of Lake Winnipesaukee, and reference the corresponding tables for more details. Specific bloom locations reported to NHDES (photos and sampling information when applicable) within these general areas can be found on the Healthy Swimming Mapper. The resampling results shared below are not reflected as reported bloom points on the map. You can help us track the bloom moving forward by reporting through the bloom report form.
The cyanobacteria identified in all areas is Gloeotrichia, which is typically observed this time of year on Lake Winnipesaukee. Though it usually occurs at lower densities, surface accumulations should be avoided. When the density looks like a starry night, the risk of recreation is low. If the density looks like a galaxy, or forms a surface accumulation, the risk to recreation is higher. Gloeotrichia is very dynamic and will quickly move around the waterbody based on wind, wave and boat action.
Low density Gloeotrichia presence was also reported in the Center Harbor area at Leavitt Park, and on the Moultonborough neck at Long Point and across from Black Cat Island. Sampling performed on September 4th showed no cyanobacteria presence at the Center Harbor Town Beach, or at Leavitt Park.
Additionally, low density Gloeotrichia presence was also reported in the Meredith area in Meredith Bay. A sample from the Meredith Town Docks taken September 4th had no cyanobacteria present. These reports are not on the Healthy Swimming because they are outside the areas with confirmed high densities of cyanobacteria.
Warnings are issued when cyanobacteria cell counts exceed 70,000 cells/mL. Watches are issued when the cyanobacteria density is below, but approaching the recreational threshold. NHDES advises lake users to not wade or swim in or near the vicinity of a bloom during a warning or watch.
Please also keep pets and livestock out. Warnings and watches are intended as precautionary measures for short term exposure. See our newly updated FAQs for more information.
Please continue to report bloom locations through the bloom report form. You can see cyanobacteria details on the Health Swimming Mapper , in addition to specific areas where bloom conditions have been reported to NHDES. NHDES will resample in a week, when watch and warning status will be reevaluated for all posted areas of Lake Winnipesaukee.
The CyanoHAB Team
Cyanobacteria Harmful Algal Bloom Program
Watershed Management Bureau, Water Division
New Hampshire Department of Environmental Services
Warnings are issued for generalized areas where harmful cyanobacteria blooms have been recently identified, but the whole waterbody may not be simultaneously impacted.
Showell Pond, Sandown – issued on 8/21/2024
Arlington Mill Reservoir, Salem – issued on 8/22/2024
Emerson Pond, Rindge – issued on 8/29/2024
Lake Ivanhoe, Wakefield – issued on 9/3/2024
Warren Lake, Alstead – issued on 9/4/2024
Jenness Pond, Northwood – issued on 9/4/2024
Halfmoon Lake, Alton, Barnstead – issued on 9/4/2024
Lake Monomonac, Rindge – issued on 9/5/2024
Current Cyanobacteria Watches (Alerts)
Lake Winnipesaukee, Alton Area – issued on 8/19/2024
Lake Winnipesaukee, Tuftonboro Area – issued on 8/27/2024
Robinson Pond, Hudson – issued on 8/30/2024
French Pond, Henniker – issued on 9/4/2024
Locke Lake, Barnstead – issued on 9/5/2024
Lake Winnipesaukee, Wolfeboro Area – issued on 9/5/2024
Lake Winnipesaukee, The Broads – issued on 9/5/2024
Lake Winnipesaukee, Governor’s Island Area – issued on 9/5/2024
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