Microscopes are not that expensive, and should be employed by civic groups/citizen scientists wishing to establish tentative identifications of potentially threatening algal communities. This volume shows what some Microcystis species colonies look like, on p. 90:
'Microcystis Kuetzing ex Lemmermann (Fig. 11). This genus has irregular micro- or macroscopic colonies that are free-floating, compact or clathrate, may be composed of clustered subcolonies, and has sparsely or densely, irregularly arranged cells. The mucilage is fine, colorless, and diffuse or distinctly delimited, sometimes forming a wide margin around the cells (rarely with indistinct structures), or delimited along cell agglomerations. Cells are spherical or hemispherical after division and pale blue-green, but they appear brownish due to aerotopes (gas vacuoles) that mask the blue-green color of the protoplast. Cells are 0.8-9(9.4) micrometers in diameter and have no individual mucilaginous envelopes. Cell division is by binary fission in three perpendicular planes in successive generations. The daughter cells grow to the original shape and size before the next division.
Based on current revisions, about 25 planktonic species are known worldwide, and many form dense blooms in eutrophic waters (Reynolds CS, Walsby AE, Water Blooms [1975] Biological Review 50: 437-481). Because many strains (species) are toxic, Microcystis is one of the most important cyanobacteria in limnological studies (Gorham PR, Carmichael WW [1988] Hazards of Freshwater Blue-Greens (Cyanobacteria in Algae and Human Affairs, Cambridge University Press, pp. 403-431; Chorus I, Bartram J, Toxic Cyanobacteria in Water, Spon, London, 461 pp.). Several species have been recorded in North America, including toxic forms of M. viridis, M. aeruginosa, and M. ichthyoblabe. In a few North American species, including M. natans, M. smithii (as Aphanocapsa pulchra), M. flos-aquae, and M. wesenbergii, toxicity has not been recorded or definitely proved. Identification of species is difficult and further taxonomic investigation is needed.
At least 50% of the species in the genus are restricted to tropical and subtropical regions . Of these, M. comperei was described from Cuba and other species probably occur in southern locations. M. glauca, recorded from the United States by Smith (1950), and other species (denoted Polycystis firma, P. pulverea, and P. marginata) were recorded from North Carolina by Whitford LA and Schumacher GJ [1969] A Manual of Freshwater Algae in North carolina, North Carolina Agricultural Experiment Station Technical Bulletin 188: 1-313, but they are taxonomically uncertain.'
(Freshwater Algae of North America: Ecology and Classification)