Ask Mr. Smarty Plants

Below are ssuggestions for several grasses and sedges that should work in your retention pond.  They are all native to Jefferson County or an adjacent county in Missouri.

Bouteloua dactyloides (Buffalograss) would be an ideal solution as long as the retention pond doesn't hold water often.   It grows to only 8 to 12 inches, requires no fertilizer or additional water.  It does occur in neighboring St Louis County.  Here is one of our How to Articles, Native Lawns: Buffalograss, with more information about the grass and how to plant and care for it.

Digitaria cognata (Carolina crabgrass) is a relatively short grass that is native to Jefferson County.  Here is more information from University of Michigan Herbarium and from The Samuel Roberts Noble Foundation.

Hordeum jubatum (Foxtail barley) is an attractive grass that grows to about 20 inches high. Here is more information from Illinois Wildflowers and from Outsidepride.com in Oregon.

Sedges are also a possibility.  They usually don't grow as tall as grasses and will usually tolerate growing in very wet soil which could occur in the retention pond.  The ones listed below are evergreen or semi-evergreen.

Carex texensis (Texas sedge) is evergreen.  Here is more information from Niche Gardens in North Carolina and San Marcos Growers in California.

Carex blanda (Eastern woodland sedge) is evergreen.  Here is more information from Illinois Wildflowers and from Missouri Plants.

Carex pensylvanica (Pennsylvania sedge) is semi-evergreen and grows to only 6 to 8 inches high.  Here is more information from Illinois Wildflowers and from American Beauty Native Plants in Delaware.

You might try a combination of grasses and sedges at first to see what grows the best in your retention pond area.  It will depend on the amount of sun, the soil type and water availability.