branch, brook, canal, creek, flume, headrace, headstream, rill, river, rivulet, run, runnel, streamlet, tailrace.
Your query has returned 1095 words, which include anagrams of watercourses as well as other shorter words that can be made using the letters included in watercourses.
The words in this list can be used in games such as Scrabble, Words with Friends, Wordscapes and other similar games.