As reported, the Cascade Mountains variety:
Algae have been used as vital staple foods in human dietary traditions throughout the world. Most well known are the many ocean algae, commonly called "seaweeds" or "sea vegetables" traditionally eaten by coastal peoples of both the East and West. Freshwater algae also formed an important part of many culinary traditions, such as in parts of Africa and Central America. However, unlike the case with seaweeds, by the time we discovered this most ancient miracle, all the viable natural sources for harvesting freshwater algae were either too polluted or too ravaged by drought to serve any purpose.
Then, in the early 1980s, a single researcher discovered one overlooked, solitary source for the most remarkable blue-green algae of all, Aphanizomenon flos-aquae - and he found it growing organically and abundantly in the wild, within the United States, in an environment that is in the pristine environment of the Cascade Mountains - and, in fact, is the richest biomass producer on the planet.