Greater Columbus Swim League & COSA.
GCSL is made up of 7 local swim teams (Annehurst-Piranhas, Delaware- D.A.R.T.S., Highlands Park- Otters, Northwest-Tiger Sharks, Plain Township-Gators, Westerville JC- Pool Cats, &  Worthington-Waves).  The purpose of the Greater Columbus Swim League (GCSL), is to provide a complete swimming and diving program for age group athletes by conducting annual competition through a series of dual meets between the participating member clubs and concluding with a League Championship Meet to determine individual and team league champions.
 http://www.gogcsl.org/

COSA is a development league whose purpose is for the participate to have fun, encourage learning of the sport, and the overall success of the swimmer. These meet will take place Saturday mornings through out the swim season.  This link is to the cosa cut off times.doc. If the swimmer has a faster time than the one listed they have "timed out" of that event and are not eligible to swim in that event.