(a) Before acting on any permit application, the Department shall weigh all respective public advantages and disadvantages and make all appropriate investigations. If the Department believes from the evidence before the Department and based upon State water resources policy declared in this subtitle that the applicant's plans provide greatest feasible utilization of the waters of the State, adequately preserve public safety, and promote the general public welfare, the Department shall grant the permit to appropriate or use the waters, construct, reconstruct, or repair the proposed reservoir, dam, or waterway obstruction, or accomplish any combination of these objectives. If the Department believes from the evidence before the Department that the proposed appropriation or use of State waters or proposed construction is inadequate, wasteful, dangerous, impracticable or detrimental to the best public interest, the Department may reject the application or suggest modifications to the proposed plans to protect the public welfare and safety.