The cost of building a backyard waterfall can vary greatly depending on the size and complexity of the project. Generally, you should expect to pay anywhere from $2,000 to $10,000 for professional masonry and landscape design services. This includes labor costs for excavation, installation of rocks or boulders, construction of a pond or pool with filtration system, and any other necessary materials. It is important to note that these estimates do not include additional costs such as permits or landscaping plants which may be required in some areas.