Bring your own pen or pencil, and maybe a log retreving tool.
Retention, the continued control of something. The action of absorbing and continuing to hold a substance. So that's what a retention pond is. To hold the drain off from the streets. It also is a home of frogs, bugs, and weeds. It also is a place to find a cache.
Many people walk their dogs around this retention pond. There's not always water in the pond, but there is always weeds. So have fun finding the cache,. and maybe the CO might honk at you if he happens to drive by.