Todd Roberts Sousa, 39, pleaded guilty to court offers in June this year and in October 2011 to 19 felony counts of lewd acts on a child, four felony counts of unlawful sexual intercourse, two misdemeanor counts of contributing to the delinquency of a minor, according to the OCDA.
Sousa must register as a sex offender for the rest of his life.
Sousa co-owned Swim Venture, an Orange County-based swim school and program for kids and adults and taught classes.
Sousa was convicted of having a sexual relationship with a 15-year-old girl he met while he was her swim instructor. That led to a sexual relationship with a 16-year-old female friend of the first victim.
The 15-year-old girl's parents learned of the relationship and contacted police. The parents also discovered the second relationship.
Sousa's mandatory lifetime sex offender registration will bar him from entering county recreational areas and city parks that have passed the sex offender ordinance.