check with your County Agent......

google search your county and county agent..... should get a number to call

There are several chemicals out there now that will not harm fish or animals but will kill the aquatic plants. Do a search on it. We used it on our ponds a few years back but I cannot remember the name.

Take pictures of the aquatic vegetation growing in the pond.  Then take those pictures to the county extension agent so he can help you identify the plants.  Once you know the exact species you just match the plant species with the proper herbicide and follow the instructions on the label.  If you send me any pictures that you have (john@texashuntfish.com), or post them here, I can help you ID the plants and recommend a treatment.

How many acres and how deep?  How deep is the organics (muck) on the bottom?  There are herbicides and bio-organisms that can be used to clean up nutrient rich algae infested water.  Other plants need to be identified so the appropriate herbicied can be applied.  This is one oif the best sites for plant ID of aquatic species in Texas: http://aquaplant.tamu.edu/  It will help you ID and solve plant problems.  Good luck, and if you have any other specific questions feel free to E-Mail me directly.