In this chapter, the following terms have the meanings indicated. Terms Defined. “Consumptive water use” means that portion of a water withdrawal which, as a result of evaporation, interbasin diversions, or other means, is not returned to the source to be available for subsequent use. “Department” means the Department of the Environment. “Low flow augmentation” means the provision of water, through development of new water storage facilities or the purchase of storage space in existing water storage facilities or both, equal to the amount of consumptive use. Permits issued or amended by the Department for nonresidential surface water appropriation in the Potomac River Basin upstream from Little Falls after January 1, 1985, shall condition the withdrawal of water on the provision, by the permittee, of low flow augmentation for consumptive water use, if the maximum consumptive water use can exceed 1 million gallons per day (mgd) at any time. Low flow augmentation shall be required whether the 1 mgd level is obtained under one permit or reached incrementally under successive new or amended permits for the same project. As an alternative to the provision of low flow augmentation, permittees may cease consumptive water use during certain periods specified by the Department or may reduce consumptive water use to levels of 1 mgd or less. Consumptive uses associated with all water appropriation permits for nonresidential water use before January 1, 1985 are exempt from the required low flow augmentation as to the level of consumptive water use before January 1, 1985. Permittees operating under existing water appropriation or use permits that increase consumptive use beyond 1 mgd without increasing withdrawal shall obtain a new water appropriation permit and shall also be subject to the provisions of this regulation for that amount consumptively used which is in excess of 1 mgd and which was not previously exempt from this regulation as a result of having occurred before January 1, 1985. If the Department determines that the combined effects of upstream permittees consumptively using less than 1 mgd may significantly increase the risk of imposing water use restrictions under the Potomac River Low Flow Allocation Agreement, the Department may require low flow augmentation of the permittees in a manner appropriate to their operations. Surface water appropriation and use permits issued or amended for municipal residential water uses upstream from the Washington metropolitan area shall contain a condition that requires the permittees to reduce withdrawals from the Potomac River or tributaries of the Potomac River when the restriction stage is declared in the Washington metropolitan area under the provisions of the Potomac River Low Flow Allocation Agreement. Subject to the Department's approval, provision of low flow augmentation by the permittee may occur at any location within the Potomac River Basin above Great Falls regardless of the location of the consumptive use. The Department may require the permittee situated on a tributary of the Potomac River to locate the low flow augmentation facility upstream from the point of withdrawal if deemed necessary for the environmental protection of instream values. The amount of required low flow augmentation shall be calculated for the location at which the withdrawal occurs or, if the consumptive use occurs on a tributary and augmentation is provided on the Potomac River, at the confluence of the tributary and the Potomac River. The total amount of low flow augmentation storage, in billions of gallons, required of a permittee by the Department shall be interpolated from the following table: The Department shall direct the permittee as to when and for what duration consumptive water use must cease or a release from a water storage facility must be made for low flow augmentation for consumptive water use. Total nonexempt consumptive use on a daily basis by a permittee may not exceed the value used in calculating water augmentation requirements during low flow restriction periods. If the permittee elects to construct the low flow augmentation storage facility in Virginia, West Virginia or Pennsylvania, the permittee shall secure the necessary agreements with the appropriate jurisdiction to enable the permittee to operate the augmentation facility in compliance with this regulation. Municipal residential water use permittees, upstream from the Washington metropolitan area, when notified by the Department that the water use restriction stage had been declared in the Washington metropolitan area, shall reduce all withdrawals from the Potomac River Basin or its tributaries to a level corresponding to the average daily withdrawal by the permittee during the previous January, February, and March. Permittees no longer consumptively using water may transfer their investment in low flow augmentation facilities to other existing or new consumptive users. The Department shall be notified by the transferor at least 10 days before any transfer of their investment in low flow augmentation facilities. Environment Article, §§5-203, 5-502, and 5-507, Annotated Code of Maryland Effective date: September 23, 1985 (12:19 Md. R. 1847) Chapter recodified from COMAR 08.05.09 to COMAR 26.17.07, June 1996