Accepting prize money from any race could be detrimental to your chances of competing in the NCAA. There are very strict rules regarding the amateur status of all athletes competing at the collegiate level. If you will be attending a college or university in the near future, are currently enrolled in college, or still have NCAA eligibility from a previous enrollment, do not accept prize money at races.

Each division in the NCAA has its own set of specific requirements, but the general rule is if you want to compete in the NCAA on any level, do not accept prize money until your eligibility has been used. If you plan to use NCAA eligibility, then do not risk losing it or facing other penalties by accepting prize money for your running performances.

From NCAA.org:
If a student-athlete has never enrolled full-time in any college, he/she may receive awards for athletics participation. The award(s) needs to conform to the rules of the amateur sports organization that governs the competition and cannot include cash. The awards presented to the student-athlete may include gift certificates and items that are not personalized, provided the awards are permitted by the rules of the amateur sports organization.

[If you are not yet in college] You may wish to consult with your high-school athletics director to determine exactly what type of award(s) you may receive.

NCAA Amateurism FAQs