Reclaiming Ohi:yo'- Restoring the Altered Landscape of the Beautiful River

The Threat of Blue-Green Algae

One of the negative environmental effects of the inundation of Ohi:yo'  has been the increasing occurrence of harmful algal blooms (HABs) throughout the Allegheny Reservoir. HABs are comprised of cyanobacteria, blue-green algae, that may negatively affect our people's health as well as have negative ecological and biogeochemical impacts.

Blue-green algae is naturally occurring in lakes and streams, and not all cyanobacteria produce toxins. The toxins produced by blue-green algae is referred to as cyanotoxins and vary by species of cyanobacteria. 

HABs with or without toxin production can have negative ecological, biogeochemical, and health impacts, and are becoming an increasingly worldwide problem. HABs can be reservoir wide and can be found accumulating along shorelines and downwind bays. 

According to the Watershed Resources Working Group, a Seneca Nation technical advisory board, HABs were first recorded in Ohi:yo' in 1972 and today have increasingly been more severe and frequent. 

Blue-Green Algae: What is it?

Cyanobacteria are a form of microscopic blue-green algae. The rapid growth of the cyanobacteria is called a "bloom". Blooms of cyanobacteria can be found in warm, nutrient-rich, shallow water or distributed throughout the water column. The Allegany Reservoir has a combination of nutrient pollution from the drainage basin upstream and the contribution of nutrients from sediment and algal detritus that has deposited in the reservoir since impoundment producing very favorable conditions for HABs.

Blooms can produce floating scum on the surface of the water, particularly along shorelines, that is blue or green in color and is reminiscent of paint spills. HABs within the Allegheny Reservoir are monitored along the shorelines of bays and inlets of the reservoir by the Watershed Resources Working Group.


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