Head Coach James Graham announced the hiring of Zac Koerner as the new men's water polo assistant coach on May 5, 2011.

Koerner comes to Pacific after five seasons at Rio Americano High School in Sacramento, Calif., where he served as the head coach of the boy's water polo team. Under his guidance, the boys' program notched over 100 victories while claiming five straight league titles and the CIF Division II Championship in 2010. The team also qualified for three CIF DII final matches and three CIF DII semi-final matches.

Koerner currently serves as the assistant coach of the United States National Youth Team as well as serving as an Olympic Development Program expert coach running training camps in Florida and San Diego, Calif. this past year. During that time frame, he was also an instructor at the annual Holiday Camp at the United States Olympic Training Center in Colorado Springs, Colo. Since 2009, he has served as the head coach of the Central California Zone Youth Team and in 2010 was recognized as the top boys coach for Northern California while leading his team to a pair of top two finishes at the Regional Championships.

Koerner graduated from UC Irvine in 2000 after two seasons in the pool for the Anteaters.