Yes, the investment cost of both the upper and lower reservoirs should be considered when investing in pumped storage units. Pumped storage is a type of energy storage system that involves using two reservoirs, an upper reservoir and a lower reservoir, to store and generate electricity. The cost of constructing and maintaining these reservoirs can be significant and should be taken into account when evaluating the overall feasibility and economic viability of a pumped storage project. Additionally, other factors such as land acquisition, environmental considerations, and the cost of the necessary infrastructure (e.g., pumps, turbines, transmission lines) should also be considered in the investment analysis.