The National High School Coaches Association has dubbed Eileen Donahue as its Coach of the Year in field hockey, recognizing her success at the helm of the perennially championship-winning Watertown High squad. Donahue’s teams have lost just 30 games during her 28-year tenure, and as of last Sunday the Red Raiders were on an undefeated streak of 101-0-3, dating to Nov. 12, 2008. The team broke the Massachusetts record for most consecutive undefeated games in field hockey when they beat Arlington, 2-0, on Sept. 10, passing Walpole High’s record set in the mid-1990s. The Watertown squad also has won the MIAA Division 2 title for the past four straight years. Donahue’s citation will be included in the National High School Sports Hall of Fame Museum in Easton, Pa. She also was sent a trophy and a certificate recognizing her award, said the association’s executive director, Bob Ferraro.