… The state [Wyo.] has issued toxic algae advisories at 20 lakes and reservoirs. … Many affected waters are in watersheds where agriculture and livestock production are dominant land uses. Runoff carrying fertilizer, manure and eroding soil can deliver phosphorus and nitrogen to streams and reservoirs, feeding the toxic algae. Livestock with direct access to waterways and irrigation return flows can also contribute pollution. In more developed areas, failing septic systems and sewage discharges can add to this problem. Warmer water creates conditions in which outbreaks occur more readily. … Wyoming should examine the pollution sources most likely to affect these waters and address them before toxic conditions threaten public health and recreation each summer.
–Written by Justin Hayes, the Northern Rockies Conservation Director for American Rivers.

Other harmful algae bloom news:

• Utah State University: Blog: The fish eye: Anglers at Utah Lake spot algae blooms more than most recreationists​