ozzy,
One of the leagues I work is a "Senior Colt" (i.e. 18+) league, where virtually all of the games are played on these two fields (you'll have to "zoom in" some to see the detail):
Willow Stream Park
The southern field has an outfield fence, while the northern field doesn't - although, it does have a retention pond in very deep right field.
Naturally, I always cover this during ground rules.
Some teams like to play "kill it if it goes in the pond". I don't much care one way or the other if the fielders hold their hands up. Others like to play "it's all in play". I'll go either way if both teams agree. Personally, I prefer "all in play". When those are the agreed to ground rules, I always mention that a fielder is free to go into the pond after the ball should the occasion arise.
JM