Nancy,
I expect that your ponds are storm water retention ponds.
At some point, they will need to be dredged.
At some point, surrounding vegetation may need to be replaced.
At some point, surrounding swales or berms will need maintenance.
Yes, you need reserves.
See:
STORMWATER WET POND AND WETLAND MANAGEMENT GUIDEBOOK from the EPA
Additionally:
Do you have any signage (entrance signs, road signs, etc)? That will need to be replaced over time.
Do you have painted curbs that the Association may be responsible for?
Do you have group mailboxes? That will need maintained and replaced over time.
Do you have walking trails?
Do you have fencing the Association is responsible for (or has a shared responsibility for)?
Do you have playgrounds?
Do you have fountains in the ponds for aeration?
See:
Subject: Reserve Studies/Funds 101 a thread on this forum. Take a look at the links (some broken links are repaired later in the thread) that help the Association identify things they may be responsible for that are not normally thought of.
Hope this helps.