Here is a website that ...

Here is a website that provides guidance for identifying aquatic weeds as well as provides biological, mechanical, and chemical control methods. http://aquaplant.tamu.edu/plant-identification/category-submerge-plants/ I see evidence of water sedge around the perimeter, American Pondweed, and what appears to possibly be Fan Wort or Hydrilla. There are many chemical treatments that can be used where water is for drinking water. Most have short half lives. Use of these are the only practical means of removing aquatic weeds in a short time frame. The detritus that will from once the weeds die off will become nutrients for future aquatic plankton and plants. A balance of biological population of both plants and animals is needed for a flourishing bio-system. You may want to consider a contact herbicide ranger than a systemic herbicide like Flouridone, to allow you to treat specific areas while allowing others to remain populated with weeds. Unlike the other comment, Roundup is not permitted (at least in the US) for aquatic weed control. The active ingredient, Glyphosate, is permitted and contained in many permitted formulations, but would only be effective on the sedges since it is a contact herbicide that is applied to plants above the water surface..