There are summer camps at Rochambeau and Classes du Samedi in Bethesda. I don't think they have sport-specific camps, but Classes du Samedi does have a year-round soccer program in French.

+1 for the above suggestion.

How good is your DC's French? If it's passable, just enroll her in a regular girls soccer camp in France or Quebec. (That's what we did, but in a theatre program and our DC spent several weeks speaking only in French with peers her age.)

Anyone have experience with sending their young teen abroad or domestically for a French immersion camp? Looking at the alliance Francaise sponsored ‘Cavilam’ in France, which looks good. Looking for language and sport focus, Sport ideally would be girls soccer.