Delle Donne entered needing 15 points to become the 40th player to reach the milestone. She was 7-of-13 from the field and had three of Washington's seven blocked shots.
Washington took control in the third quarter, outscoring Atlanta 20-8 to help build a 54-33 lead.
Atlanta shot just 35.7%, including 4-of-21 from distance, and turned it over 23 times.
Rookie Rhyne Howard, the league's leading scorer at 20.5 points per game, missed all nine of her shots and was scoreless in 29 minutes for Atlanta (4-3). The Dream attempted just six free throws.