Cyanobacteria Alerts

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2024

15 May 2024

The A cyanobacteria warning has been issued at your lake, please see below for details.

Waterbody Arlington Mill Pond, Salem

Status WARNING (ADVISORY)

Issued 5/15/2024

Bloom Description (picture attached) Green surface ribbons along shoreline

Cyanobacteria Taxa Dolichospermum

Cyanobacteria Density (cells/mL) 70,400

Notes Bloom accumulation coming and going, sample collected was not as dense of a bloom as reported this morning.

Warnings are issued when cell counts exceed 70,000 cells/mL. NHDES advises lake users to not wade or swim in the water during a warning. Please also keep pets and livestock out. The warning is not based on a toxin evaluation and is intended as a precautionary measure for short term exposure. Please see our newly updated FAQs for more information. NHDES will resample in a week. I will reach out to you before then for updates. If you have information on where accumulated material is being observed at that time, please let us know to guide our sampling efforts. Warnings remain active until the bloom subsides. You can also see warning details on the Health Swimming Mapper.

2023

8 November 2023

The cyanobacteria WARNING (ADVISORY) that was issued on 28 July 2023 has been REMOVED for Arlington Mill Pond as of today, 8 November 2023. While the bloom accumulation has dissipated, NHDES advises that lake-goers look out for discoloration or surface accumulations in the future. Please continue to monitor your individual shoreline for changing conditions.

The red cyanobacteria advisory signs can now be removed from public access points.

Thank you all for your communication. If you see cyanobacteria in the future, please report it here!

8 November 2023

The red cyanobacteria advisory signs can now be removed from public access points.

Thank you all for your communication. If you see cyanobacteria in the future, please report it here!

25 October 2023

Arlington Mill was resampled today, 25 October 2023. The cyanobacteria density is around the state limit of 70,000 cell/mL, so the advisory will remain active. The highest observed sample was 47,600 cells/mL (Dolichospermum, Woronichinia, and Microcystis) but surface accumulations were observed at multiple locations during sampling. Please keep signs posted at public access points.

NHDES will arrange for sampling again in the next two weeks. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

5 October 2023

Arlington Mill Pond was resampled today, 5 October 2023. The cyanobacteria density continues to exceed the state limit of 70,000 cell/mL, so the advisory will remain active. The highest observed density was 128,600 cells/mL. Bloom conditions continue to be reported around the lake. Please keep signs posted at public access points. NHDES will arrange for sampling again next week. Following 15 October, sampling frequency will be reduced to every other week. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

There have been repeated concerns about the cyanobacteria coming in from a different waterbody or river. I would like to stress again that based on our sampling the cyanobacteria are growing within Arlington Mill Pond, and not coming in from a different waterbody. Where the cyanobacteria show up in the waterbody is not necessarily where the problem is originating. Cyanobacteria grow lake wide and accumulate along shorelines based on wind, wave, boat action and lake morphology. The cyanobacteria growing in the lake are likely the result of years of excess nutrient loading. The nutrients (primarily phosphorus), or "food" for the cyanobacteria may be coming into Arlington from different tributaries, but these nutrients also come in from properties along the waterfront and anywhere in the watershed. Storm water runoff brings these nutrients into the water from lawns, septic systems, developed areas and impervious surfaces (think roofs, driveways, any pavement), etc. A watershed management plan and in-lake water quality testing, beyond what we do as part of this program, is essential for identifying the sources of these nutrients and developing projects to mitigate ongoing inputs. The process of developing a watershed management plan is led by Lake Associations, so please get involved to get this process moving. I have shared the necessary contacts at NHDES with the Lake Association to begin this process. The Cyanobacteria HAB Program is responsible for monitoring and communicating about current cyanobacteria bloom risk - we only test for cyanobacteria. We currently do not have the capacity to do the investigative nutrient testing that Arlington Mill Pond needs to determine the causes of blooms and take the steps to prevent them in the future. This work will be accomplished by the Lake Association and community pursuing a watershed management plan.

27 September 2023

Arlington Mill was resampled today, 27 September 2023. The cyanobacteria density continues to exceed the state limit of 70,000 cell/mL, so the advisory will remain active. The highest observed sample was too numerous to count (exceeded 6 million cells/mL), the most dominant cyanobacteria present was Microcystis. This sample was from the north part of Shore Drive. Another sample was reviewed from the southern part of the lake had no cyanobacteria present - this perfectly highlights the dynamic nature of cyanobacteria blooms! Please keep signs posted at public access points. NHDES will arrange for sampling again next week. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

15 September 2023

Arlington Mill was resampled today, 15 September 2023. The cyanobacteria density continues to exceed the state limit of 70,000 cell/mL, so the advisory will remain active. While three of the four samples were around the 70,000 cells/mL threshold, the highest observed sample was still 2.5 million cells/mL. Please keep signs posted at public access points. NHDES will arrange for sampling again next week. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

8 September 2023

Arlington Mill was resampled today, 8 September 2023. The cyanobacteria density continues to exceed the state limit of 70,000 cell/mL, so the advisory will remain active. The waterbody was not blooming during sampling, but the highest observed sample was still 78,700 cells/mL. There were also continued significant bloom photos shared over the previous week as well. Please keep signs posted at public access points. NHDES will arrange for sampling again next week. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

1 September 2023

Arlington Pond was resampled today, 1 September 2023. The cyanobacteria density continues to exceed the state limit of 70,000 cell/mL, so the advisory will remain active. The highest observed density was 86,000 cells/mL, however cyanobacteria were observed at all sampling locations. Please keep signs posted at public access points. NHDES will arrange for sampling again next week. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

24 August 2023

Arlington Mill was resampled today, 24 August 2023. The cyanobacteria density continues to exceed the state limit of 70,000 cell/mL, so the advisory will remain active. The highest density observed was 2,599,999 cells/mL, and four out of the seven samples collected were above the advisory level. Please keep signs posted at public access points. NHDES will arrange for sampling again next week. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

17 August 2023

Arlington Mill Pond was resampled yesterday, 17 August 2023. The cyanobacteria density continues to exceed the state limit of 70,000 cell/mL, so the advisory will remain active. Please keep signs posted at public access points. NHDES will arrange for sampling again next week. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

11 August 2023

Arlington Mill was resampled today, 11 August 2023. The cyanobacteria density continues to exceed the state limit of 70,000 cell/mL, so the advisory will remain active. Though bloom conditions were not terrible during sampling today, several significant bloom reports were shared this week, see the image attached taken 9 August. Please keep signs posted at public access points. NHDES will arrange for sampling again next week. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

4 August 2023

Arlington Mill Pond was resampled today, 4 August 2023. Though the cell count has declined to 92,200 cells/mL, the density continues to exceed the state limit of 70,000 cell/mL, so the advisory will remain active. Please keep signs posted at public access points. NHDES will arrange for sampling again next week. If people ask for updates on the current cyanobacteria advisory status, please direct them to the Healthy Swimming Mapper. If you click on the advisory symbol, you can see our most recent sampling date. When advisories are lifted, the red symbol for the waterbody will no longer be on the map.

26 July 2023

A cyanobacteria WARNING (ADVISORY) has been issued for Arlington Mill Reservoir, Salem. The bloom was first reported on 26 July, appearing as green clouds in some places, and yellow-green clouds in others. See the images attached, taken 26 and 28 July. Samples collected and reviewed on 28 July had cyanobacteria (Microcystis, Woronichinia and Dolichospermum) in concentrations up to 407,800 cells/mL in areas of highest observed accumulations. There was also a significant amount of iron bacteria present in the water. Advisories are issued when cell counts exceed 70,000 cells/mL. NHDES advises lake users to not wade or swim in the water during an advisory. Please also keep pets and livestock out. The advisory is not based on a toxin evaluation and is intended as a precautionary measure for short term exposure.