Amistad National Recreation Area is governed by Codes of Federal Regulations (CFR) and the park superintendent can "model" these regulations to fit the park's special needs.
Not all parks have water-based recreation, historical structures, or even trees. Each park is unique and has its own unique set of laws, as well as the laws that apply to every unit, such as "littering" for instance.
If the question you have in mind involves whether what you are doing is legal or not, then you can look in the Superintendent's Compendium (3.72 MB) to find your answer.
All laws and regulations are made to protect fragile natural and cultural resources, and to protect our park visitors so that we and our future generations may keep coming back to enjoy the beauty we see around us.