Camp Horsewater is the rival camp of Camp Meadowcroak. The counselor is Coach Raggett and the children that went to the camp were fourth graders, who were seen in the episode "Arthur Goes to Camp". The same kids have been seen around Lakewood and other places around Elwood City. Arthur Goes to Camp is the only episode Camp Horsewater was ever seen or mentioned and it's unknown if the camp still competes against Meadowcroak. The camp's sign has the words "Equi-Aqua" on it, which is Latin for "Horse Water". The camp has beaten Camp Meadowcroak at the annual scavenger hunt each year except for the year in Arthur Goes to Camp
Several of the kids as Camp Horsewater would soon be seen at Lakewood in a few more episodes after the events of Arthur Goes to Camp.