1. The plaintiff's appeal and the conjunctive claim added by this court are all dismissed.

2. After an appeal is filed.

The reasoning of the judgment of the court of first instance that partially accepted the judgment is "1. Facts finding" among the grounds of the judgment of first instance.

2. “Related Acts and subordinate statutes” refer to the corresponding part of the reasoning of the judgment of the court of first instance, except as follows, and thus, it is cited in accordance with the main sentence of Article 420 of the Civil Procedure Act. Two pages 14 “Permission to Occupy and use (the installation of water and structures)” (hereinafter “the first permission to occupy and use rivers”) are added “the first permission to use and use rivers”). Five pages “The River Act” is “the River Act (amended by Act No. 15624, Jun. 8, 2018; hereinafter “River Act”).

"Ero-friendly".

Plaintiff’s assertion

The main argument that A used river water after obtaining the first permission on April 22, 1985 prior to the date of the authorization on completion of a dam from October 13, 1986, which is the date of the authorization on completion of a dam. As such, A used river water from the first permission on the use of river water by 21,000 cubic meters and hereinafter referred to as “the acquired and used quantity”).

The proviso of Article 35 (1) of the Dam Construction Act, which provides for exemption from usage fees for the use of river water before the construction of the dam, shall apply to usage fees for the use of river water.

Therefore, the defendant can only collect the usage fees for the permitted volume after the construction of the D Dam pursuant to the main sentence of Article 35 (1) of the Dam Construction Act, but cannot collect the usage fees for the acquired volume, and the plaintiff has the authority to collect the acquired volume in accordance with the relevant laws and regulations.

Nevertheless, there is no legal ground for the Defendant’s collection of usage fees equivalent to the volume of acquired goods, and the payment of usage fees under this part of A is valid as repayment of good faith and negligence to quasi-Possessors of the claim, and thus, the Plaintiff has lost legitimate authority to collect, thereby causing damage to the amount equivalent thereto.

The Defendant is obligated to refund the amount equivalent to the royalty collected to the Plaintiff as unjust enrichment.

The Plaintiff’s aforementioned unjust enrichment claim, the statute of limitations period of limitation of which was imminent pursuant to Article 82(1) of the Local Finance Act, was 515,391,370 won, which was the part from August 25, 2012 to December 31, 2013, and its.