I'm a young adult just incidentally diagnosed with compensated obstructive hydrocephalus due to aqueductal stenosis; no intervention was recommended, but are there any risks or implications i should be aware of?

You may do well for several years but should have ongoing serial MRI studies to exclude progressive hydrocephalus and increasing intracranial pressure. Hopefully, you will have a neurosurgeon following you on an ongoing basis.

2 possibilities: It could stay the same or get worse. If it gets worse, you'll start to have symptoms. Fortunately, modern neuroimaging (MRI scans) can track any changes. The usual approach is to get periodic or "serial" MRIs every few years. Discuss with your doctor what that interval should be. If I were the doctor, I'd suggest every 5 years. But remember: the MRI isn't the patient; you are.