Good idea to document determination. - Particularly if you conclude you are not subject to the rule. - Not a rule requirement. See Section 2.4 of SPCC guidance document. http://www.epa.gov/emergencies/docs/oil/spcc/guidance/2_Applicability.pdf.
The age of consent is eighteen. With parental consent, parties can marry at age seventeen with the exception that if one party does not have a parent who resides in the state and one party has been a resident in Oregon for at least six months, then no permission is necessary.
In these states, such as Texas, the age of consent is determined by age differentials between the two persons and limited by a minimum age. For example, a state might set a minimum age of 14, but limit consent to partners who are within 3 years of their age.