People often think that as long as something is organic (such as leaves, grass clippings or old plants), it's alright to dump those items into a lake, river or other body of water. However, it is against state law. The Texas Health Code specifies the fine and punishment for dumping anything, including organic materials, in the waters of the state.
Among the reasons is that nutrients from an excess of organic materials or even over-fertilizing yards or gardens result in algal blooms. As the algae "blooms," it can affect both the dissolved oxygen content of the water and the pH (acidity or alkalinity). These added nutrients in the water can also cause more plant growth in lakes or rivers, leading to impaired navigation in many waterways. This is especially prevalent in shallow areas where sunlight can penetrate the entire water column.