Here's my thoughts. First, evaluate. Evaluate the dam, the spillway, the watershed and your plant community.
Use this list.
1) You need engineering help.Ask the NRCS (Natural Resources Conservation Service)if they will come inspect your dam, with the goal of raising your water level. They will have some thoughts. If you don't like what they say, enlist the services of a paid engineer and ask the same question. The answer will help decide whether to raise the dam, raise the spillway, or to forego both those options.
2) Evaluate depth of siltation in the bottom of your lake. Get out there in a boat, push a rod into the pond bottom, find soft sediment, push through to hard soils, and measure that depth. Do your checks along the bottom, in an organized fashion, in quadrants. This will give you an idea how much silt sits on bottom, in case you choose to look at draining and removing silt.
3) Evaluate the vegetation community. Identify plant species, percentage coverage of each species. This will give valuable information whether to stock more grass carp, use herbicides, or some other management strategy.
4) Here's the best advice...if you don't quite understand how and why to do the above suggestions, hire a professional pond manager to evaluate for you. It will be worth the fee.


Teach a man to grow fish...
He can teach to catch fish...