Anoxic Events

Anoxic Event - Upper Southwest River, August 17, 2021 (photo credit: David Thomas)

Anoxic events are a common occurrence in Island estuaries during the summer months.  The symptoms of an anoxic event include:

  • milky white or green discolouration of the water, 
  • H2S or 'rotten turnip' odour, and                        
  • low (near zero) dissolved oxygen readings.

A list of sites that have recorded anoxic events during 2021 is provided below.  A map of these sites is available and Historical information, from 2011 to 2020, is available.  A map that highlights the intensity of anoxic events across PEI from 2016 to 2020 is also provided.

Please note that information provided may not capture every anoxic estuary in PEI for a particular year. Some events may not have been reported to or documented by the Department.

2021* Anoxic Events


  • Anderson's Creek
  • Baltic River (Darnley Basin)
  • Barbara Weit River
  • Hope River 
  • Mill River (upper Mill River, Meggison's Creek, and Long Creek)
  • Montrose River (including Huntley Branch)
  • Oyster Creek (north branch)
  • Southwest River (upper Southwest River, Durant Creek, Tuplin Creek, and Long River)
  • Stanley River (Granville Creek)
  • Wheatley River

Freshwater Ponds:

  • Paynter's Pond
  • Round Pond

* Current to September 13, 2021

Who can I contact for more information?

Cindy Crane
4th Floor, Jones Building
11 Kent Street
Charlottetown, PEI C1A 7N8
Telephone: (902) 368-5179
Fax: (902) 368-5830


Published date: 
September 13, 2021
Environment, Energy and Climate Action

General Inquiries

Department of Environment, Energy and Climate Action
4th Floor, Jones Building
11 Kent Street
PO Box 2000
Charlottetown, PE C1A 7N8

Phone: 902-368-5044
Toll-free: 1-866-368-5044
Fax: 902-368-5830
Report an Environmental Concern