The study analyzed the planning for a hydropower plant on the Belayan River in East Kalimantan. They looked at the technical aspects of the design and the economic feasibility of the project. The plant would generate 439.4 MW of power and cost 3.67 trillion Indonesian Rupiah to build. The project has a net present value of 3.91 trillion Rupiah, a return on investment of 7.77 years, and a break-even point in 11.36 years. The benefit-cost ratio is 1.32, and the internal rate of return is 19.53%. Overall, building the hydropower plant in East Kalimantan is economically viable.