Mach,

Aquatic vegetation can dramatically enhance or detract from your ponds function and aesthetics. There are two things you need to take into consideration for your project to be able to maximize your enhancement value and minimize your destructive value:

1. Determine your goals...this will be your guiding light in how you make the decisions below

2. Use native, non-invasive plant species. i.e. not hydrilla.

3. Use vegetation that is native to your geographic region.

4. Use vegetation that is hardy to your soils and water chemistry for your area.

5. Make sure the vegetation you use is not on the illegal and prohibited species list in your state and USDA.

USDA's List:
Federal List--From the USDA APHIS
Federal list from: USDA/APHIS/PPQ. Part 360 -- Noxious Weed Regulations. Authority: 7 U.S.C. 2803 and 2809; 7 CFR 2.17, 2.51 and 371.2(C).

Aquatic/Wetland

Azolla pinnata: mosquito fern, water velvet
Caulerpa taxifolia: Mediterranean clone of caulerpa)
Eichhornia azurea: anchored water hyacinth
Hydrilla verticillata: hydrilla
Hygrophila polysperma: hygro, Miramar weed
Ipomoea aquatica: water spinach
Lagarosiphon: major African elodea, oxygen weed
Limnophila sessiliflora ambulia
Melaleuca quinquenervia melaleuca
Monochoria hastata monochoria
Monochoria vaginalis
Ottellia alismoides: duck-lettuce
Sagittaria sagittifolia
Salvinia auriculata: giant salvinia
Salvinia biloba: giant salvinia
Salvinia herzogii: giant salvinia
Salvinia molesta: giant salvinia
Solanum tampicense: wetland nightshade
Sparganium erectum: exotic bur-reed

* Remember federal rule supersedes state and local rule.

Reevaluate your goals and make sure they are being met with the vegetation plan you've chosen.

Good luck!