We’ve received a number of calls regarding a blue green algae (cyanobacteria) die off on Center Lake today (attached photos).  Center Lake has been more prone to these blooms in recent years, and this one is impacting Hayward’s Bay on West Okoboji Lake.  Water entering West O is bluish in color and has probably lowered the dissolved oxygen resulting in stressed and dying fish in the vicinity.  I supplied KUOO radio with an interview this morning regarding this bloom and the impact to West Okoboji.  There have been rumors that this strange colored water is from a chemical (copper sulfate) spill or treatment.  It is a result of the cyanobacteria die off on Center Lake.  Warm water and very little wind have provided excellent conditions for blue green blooms on many area lakes.

A number of local partners have been trying to get a restoration project off the ground for Center Lake over the past few years.  There is great local leadership and a lot of positive interest.  There are several contributing factors for this bloom, but the highly altered Center Lake watershed and excess of nutrients, mainly phosphorus, are the major contributors.  The City of Spirit Lake has a drainage improvement plan on the shelf for the residential/urban portion of the watershed that includes measures to slow and treat runoff.

This recent bloom really drives home the point that there is a lot of work ahead of us to protect these precious resources.  This is just one lake on a long list of lakes needing restoration work in northwest Iowa.

Please pass this information along to any local folks that may have concerns.  Wikipedia does a pretty good job of giving an overview of blue green algae (cyanobacteria) at the following website.



Mike Hawkins

Fisheries Management Biologist

Spirit Lake District

Iowa Department of Natural Resources

122 252nd Ave

Spirit Lake, IA 51360


712-330-1849 (mobile)