Suggestion: Allow reviewers to enter a park's map coordinates - latitude and longitude. Then we could use that information with our navigation systems to map the location of the park.
Then once you or one of the other moderators checks the coordinates lock them so that no other reviewer can change them. You could verify them using Google Earth.
And you could add a Google Earth link to the description of the park so we could easily see the parks layout. To see how this works click this link to show where I am today:
I use Delorme Street Atlas. It allows me to enter map coordinates. It would be easier than trying to find the park using street address, etc.