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.
If a person lives in a state where the age of sexual consent is, for example, 16 and is dating a 16- or 17-year-old in another state where the age of consent is also 16, that would violate this federal law, even though any particular activity the two people may engage in would be legal in both their states.