Sorry, should have done this before I posted my first---
from the County Website:
Gather your valid and current New York State Driver's License and other proof of residency, i.e. property tax bill.
2. Go to a Nassau County Park.
3. If you are older than 13, or if you are a golfer of any age, pay $15 for a three year Passport.
4. If you are a senior citizen over age 60, or if you have a disability, pay a one-time fee of $15.
5. Get your Leisure Passport.
6. Use your Passport to enjoy all Nassau County Parks and their facilities.
Tips:
Get Your Leisure Pass at these Nassau County Parks: Cantiague, Christopher Morley, Eisenhower, Grant, North Woodmere, Wantagh
For more information, call the Nassau County Department of Recreation and Parks: (516)572-0214.
I guess Wantagh is closest for me.
BTW, love your avatar pic, T.