I can give you a list for field hockey. I can be a little obsessive with research so when my kids displayed a glimmer of interest in field hockey (my high school sport), I started researching summer camps.
Champions - Camps in Rockville
http://www.championsfieldhouse.com/fhockey_events.shtm
Bullis in Potomac -
http://www.bullis.org/summer-programs/athletics/field-hockey/index.aspx
Koa Sports - camp at St. Andrews in Potomac -
http://www.koasports.org/programs/summer-camps/
OBGC - in Olney they have run the Mulholland field hockey camp in the past
http://www.obgc.com/
Good Counsel in Olney
https://www.olgchs.org/page.cfm?p=4423
If you are willing to go out to McLean, VA, Beyond Sticks is running a camp at the Potomac School in McLean - there is an open house April 19th
http://www.beyondsticks.com/
I think American University has a day camp but it may start in HS
There are quite a few overnight camps for ages 10 and up. You can also do most as a day camp but price is almost the same.
Advanced Play has UMD location
http://advancedplay.org/
Nike has one at McDaniels College in Westminister
http://ussportscamps.com/fieldhockey
Revolution field hockey has locations at Hopkins, Catholic Univ,
http://www.fhcamps.com/
Good luck.