In fisheries we call these properties turbidity. If turbidity is muddy or dirt colored it can be due to soil sediment displacement caused by either mechanical or chemical disturbances. Mechanical disturbances are basically something physically moving the soil sediment around. This could be "trash fish", wind, livestock, or runoff. Chemical disturbances are due to the charge of the soil particles and the charge of the water. Neither mechanical or chemical disturbances are more common however, I do feel that chemical disturbances are usually much easier to fix.
You can narrow down the cause of soil disturbance in your lake with a very simple and cost free bucket test. The bucket test is done by taking two 5 gallon white buckets and filling them with lake water. The buckets should be placed into the barn and most importantly out of sunlight. One bucket should be just lake water and the second should have one penny sized piece of drywall in the lake water. Each day the buckets should be check to determine if either bucket has starting clearing. If the water clears in the lake water only bucket over about a one week time then the water clarity is being controlled by a physical factor. Therefore you may have something physically disturbing the soil sediment in the lake and you need to take a better look at the lake design, or conduct an electrofishing survey to look for "trash fish". If the lake water only bucket does not clear then the lake turbidity may be controlled by a chemical factor. If the water in the dry wall and lake water bucket clears then an application of gypsum rock would potentially clear the lake and reverse the chemical factors affecting the clarity of the water.
Gypsum (CaSO4) is fairly water soluble mineral that can be found in fertilizers, drywall, plaster, and mixed in many other products. Gypsum is pH neutral therefore its application does not have the risk associated with alum treatments. Gypsum works by attracting clay particles together to form clumps or what we call floccules. As the clay particles continue to clump they eventually increase in weight and settle to the bottom.
Over the past few years I have done dozens of gypsum rock applications to clear turbid lakes. I have applied gypsum powder by boat over the entire water body, I have dumped tubs of large gypsum rock off the side of boats, I have built dump platforms for the front of boats, and I have used a tractor to just pile it up in one location. What I have found is that gypsum powder will result in a more rapid clarity however, it is generally very short lived (less then one month). The larger gypsum rock offers a longer lasting clarity (5+ years in many cases) but will take up to 4 weeks to gain the clarity desired. If using the powder you must spread the gypsum over the entire water body. When using the large rock however, I have seen no difference when water bodies are under 20 surface acres in applications over the entire water body or in just one location.
Luckily for Texas lake owners gypsum rock mines can be found in a couple locations and rock can be hauled directly to your property in large quantities fairly inexpensively. Every lake will need a different application amount to produce the clarity desired. Expect to use 500-1000 lbs per acre ft of water.