Miller, 34, was with his brother on the rain-swollen waters in Birmingham Township when the two plunged over a four-foot dam at about 1:20 p.m. Tuesday.
Both went underwater and when they didn't come up right away, park staff called rescuers.
Rescuers found Christopher Miller, 28, of Yonkers, N.Y., and took him to Chester County Hospital, where he was pronounced dead.
Chad Miller, a native of Sandwich, Ill., was the pastor of missions and youth at Westminster Presbyterian Church in Wilmington.
Westminster Presbyterian Church (1502 West 13th Street, Wilmington, Del.) will hold a memorial service Sunday, June 14 at 10:00 a.m. to honor his life and ministry work, according to a church administrator.