The use of water described in section 46-636 may only be made after securing a permit from the Department of Natural Resources for such use. In approving or disapproving applications for such permits, the Director of Natural Resources shall take into account the effect that such pumping may have on the amount of water in the stream and its ability to meet the requirements of appropriators from the stream. This section does not apply to (1) water wells located within fifty feet of the bank of a channel of any natural stream which were in existence on July 1, 2000, and (2) replacement water wells as defined in section 46-602 that are located within fifty feet of the banks of a channel of a stream if the water wells being replaced were originally constructed prior to July 1, 2000, and were located within fifty feet of the bank of a channel of any natural stream.