Is this patk equipped with a pavillion that holds about 250 people and does the park offer swimming?

Yes it's!!

Yes, we have shelters that hold up to 250 people in the Pickall area of the park. You may make a reservation my visiting Http://parkreservations.maryland.gov or calling 1.888.432.2267. Also, while there is no designated swimming area or "pond", you may swim at any point in the river except where there are signs posted 'no swimming' or within 300 feet of a dam. If you have additional questions, you may also call the park office at 410.461.5005.

Certain parts offer swimming and larger pavilions. Give them a call

There is a swimming pond, not open at the moment. A few pavilions, not sure what they accommodate.