(1) In every case in which the state engineer finds that water can be stored out of priority under circumstances such that the water so stored can be promptly made available to downstream senior storage appropriators in case they are unable to completely store their entire appropriative right due to insufficient water supply, the state engineer may permit such upstream storage out of priority, but such storage water shall be promptly released on demand of a downstream senior whenever needed by such senior for actual use.

(2) Individuals and private or public entities, alone or in concert, may provide a substituted supply of water to one or more appropriators senior to them, not to exceed that to which any senior appropriator is entitled from time to time by virtue of his appropriations, and, to the extent that such substituted water is made available to meet the appropriative requirements of such senior, the right of such senior to draw water pursuant to his appropriation shall be deemed to be satisfied. The rights of such senior may be used for effectuating such substitution during the period while it is in operation, and the practice may be confirmed by court order as provided for determining water rights.

(3) Any substituted water shall be of a quality and continuity to meet the requirements of use to which the senior appropriation has normally been put.

(4) Whenever substitute water is supplied to a senior ditch, the supplier or his assignee may take an equivalent amount for beneficial use from water of the state of Colorado to the fullest extent possible without impairing the availability of water lawfully divertible by others. A practice of substitution or exchange pursuant to law may constitute an appropriative right and may be adjudicated or otherwise evidenced as any other right of appropriation.

(5) In determining the quantity of water required as a substitute supply to replace evaporation from groundwater exposed to the atmosphere in connection with the extraction of sand and gravel by open mining as defined in section 34-32-103 (9), C.R.S., there shall be no requirement to replace the amount of historic natural depletion to the waters of the state, if any, caused by the preexisting natural vegetative cover on the surface of the area which will be, or which has been, permanently replaced by an open water surface. The applicant shall bear the burden of proving the historic natural depletion.

(6) In determining the quantity of water required as a substitute supply to replace stream depletions in connection with any mining operation as defined in section 34-32-103 (8), C.R.S., for which areclamation permit has been obtained as set forth in section 34-32-109, C.R.S., there is no requirement to replace the amount of historic natural depletion to the waters of the state, if any, caused by the preexisting natural vegetative cover and evaporation on the surface of the area that will be, or that has been, eliminated or made impermeable as part of the permitted mining operation. The applicant bears the burden of proving the historic natural depletion.