GILBERT, Ark. (AP) — About two dozen volunteers have recently completed an algal survey on a stretch of Arkansas waterway just weeks after federal officials issued warnings about it.

A group scientists, students and activists met in Gilbert last month for a half-day training workshop before spending the next day documenting the algae found on the Buffalo National River, the Baxter Bulletin reported . The river is known as a popular spot for rafting, fishing and canoeing.

The survey comes after the Arkansas Department of Environmental Quality recommended July 26 that 14 miles of river be declar...