Hi Ryan 

Before you start on the rescue plan, you need to think about what you are doing to prevent someone falling in and the precautions that are or are not practical.

Given the limited detail in your posting it is impossible to guess what might be appropriate. Would depend on multiple variables including, inter alia, location and population at risk.

So, you are in a mini version of the annual question "how many life rings should be provided at Loch Lomond?"

P

The highest priority is as Peter said  is to make sure people don’t fall in. This of course depends where these balancing ponds are; are they on busy campus or office park with loads of people about or are they hidden away in the corner of the site with limited access. Are they an “attraction”; do people regularly go paddling in the or fishing or are they full of disgusting slimy water that no one  would enter  given the choice. How big are  they? Is there a path all the way round or is there berm like structure all the way meaning it’s hard to get to and hard to get out of?

You should note that there is no legal requirement to provide  a rescue capability and for  the example the Environment Agency have been removing  life buoys etc from around rivers etc which they manage on the grounds that in practice they are fairly useless as they are never in the right place ie to where the person has fallen in and most have been vandalised anyway.

So as Peter says be practical and realistic.