Section 096-587-2 - DefinitionsA.Natural drought condition. "Natural drought condition" means moisture conditions as measured by the Palmer Drought Severity Index with values of negative 2.0 or less.B.Natural variation of flow. "Natural variation of flow" in rivers and streams is the expected dynamic fluctuation in flow that naturally occurs daily, seasonally and inter-annually that provides for physical characteristics of depth, volume, and velocity necessary to (1) provide habitat conditions for all life stages of indigenous aquatic organisms, (2) provide water exchange and aeration including the interstitial water, substrate scouring and sorting, temperature moderation, wetland replenishment, sediment erosion and deposition, and channel formation, and (3) maintain biological processes of ingress and egress to habitats, migration, drift, insect emergence, organic matter and nutrient cycling, and wetlands maintenance. In establishing site-specific water flows as set forth in sections 7 and 8 of this chapter, flow variation of a magnitude, rate of change, seasonal timing, and annual occurrence, including provision for infrequent passage or release of flood flows, must be sufficient to adequately provide for the conditions and processes identified above.C.Natural variation of water level. "Natural variation of water level" in lakes and ponds is the expected dynamic fluctuation in water level that occurs seasonally and inter-annually that provides for physical characteristics of depth and volume necessary to (1) provide habitat conditions for all life stages of indigenous aquatic organisms, (2) provide water levels sufficient to support important physical processes including thermal stratification, temperature moderation, wetland replenishment, sediment erosion and deposition, (3) maintain biological processes of ingress and egress to habitats, maintenance of primary production, migration and movement of organisms, organic matter and nutrient cycling, and wetlands maintenance. In establishing site-specific water levels as set forth in sections 7 and 8 of this chapter, variation of a magnitude, rate of change, seasonal timing, and annual occurrence, including provision for infrequent flood levels, must be sufficient to adequately provide for the conditions and processes identified above.D.Normal high water. "Normal high water " means that elevation determined from a line along the shore of a Class GPA waterbody which is apparent from visible markings, changes in the character of soils due to prolonged action of the water, or from changes in vegetation and which distinguishes between predominantly aquatic and predominantly terrestrial habitat.E.Seasonal aquatic base flow. "Seasonal aquatic base flow" is a median flow value for the following seasons: winter (January 1 to March 15), spring (March 16 to May 15), early summer (May 16 to June 30), summer (July 1 to September 15), fall (September 16 to November 15), and early winter (November 16 to December 31). Seasonal aquatic base flows are established as follows. (1) For the winter season January 1 to March 15: a flow equal to the February median monthly flow as determined according to section 3 of this chapter.(2) For the spring season March 16 to May 15: a flow equal to the April median monthly flow as determined according to section 3 of this chapter.(3) For the early summer season May 16 to June 30: a flow equal to the June median monthly flow as determined according to section 3 of this chapter.(4) For the summer season July 1 to September 15: a flow equal to the August median monthly flow as determined according to section 3 of this chapter.(5) For the fall season September 16 to November 15: a flow equal to the October median monthly flow as determined according to section 3 of this chapter.(6) For the early winter season November 16 to December 31: a flow equal to the December median monthly flow as determined according to section 3 of this chapter.F.System Design Capacity. "System design capacity" for authorized Community Water Systems withdrawing from surface waters shall be determined by the Department of Health and Human Services as the amount of water that is available for Community Water System purposes expressed as annual withdrawal in total gallons per year taking into consideration actual documented annual withdrawal, and the investments in and limits of the existing system infrastructure, that provides a safe and dependable supply of water for public use. Existing system infrastructure includes water treatment and distribution facilities and other necessary structures that determine how much water can be safely and dependably supplied that is present or in the process of being acquired such as through an investment bond, contractual agreement, or purchase order as of the effective date of this chapter.G. Water User. For the purposes of this Chapter, "water user" means a person whose withdrawal or other direct or indirect removal, diversion, activity, or use of these waters by means of a structure or facility causes the natural flow or water level to be altered in any non-tidal fresh surface waters of the State.06- 096 C.M.R. ch. 587, § 2