New Jersey Highlands CouncilA central goal of the Regional Master Plan is to determine the amount and type of human development and activity that the ecosystem of the Highlands Region can sustain while still maintaining the overall ecological values thereof, with special reference to surface and ground water quality and supply. Based on an analysis of available methods and available data, the Low Flow Margin method was selected as the best scientific approach available at this time for estimating capacity of ground water supplies across the entire Highlands Region, to maintain both ecological flow needs and estimate sustainable levels of human consumption. The Low Flow Margin method uses two low flow statistics, and is derived using statistical analyses of data from reference drainage basins with minimal consumptive water uses. The HUC14 subwatershed was selected as the smallest drainage area available for application of the method. The Highlands Council collaborated with the US Geological Survey, Water Resource Science Unit to develop Low Flow Margin results for each HUC14 subwatershed based on data from reference drainage basins with stream flow gaging stations to determine the Ground Water Capacity for each of the 183 HUC14 subwatersheds that occur within the Highlands Region. A key issue for water availability estimates is to what extent Ground Water Capacity should be made available for both current and future human uses. It is important to recognize that the Highlands Act emphasizes that human water uses should be constrained by ecological needs. Therefore, only a portion of Ground Water Capacity is considered available for human use, with the majority being reserved for ecosystem integrity. That amount, called Ground Water Availability, is defined as the portion of Ground Water Capacity that is available for consumptive and depletive human use without harm to ecosystems of the Highlands Region. Utilizing this method, Ground Water Availability is obtained by multiplying Ground Water Capacity by a percentage threshold, of water availability as shown below: Ground Water Availability = (Ground Water Capacity) * (% Water Availability Threshold) In the most ecologically sensitive HUC14 subwatersheds, Ground Water Availability should be severely limited to protect aquatic ecosystems and the related terrestrial ecosystems. For other HUC14s, a graduated scale is appropriately based on ecological values. HUC14s with concentrated development or agriculture and limited ecological constraints would be assigned a higher portion of Ground Water Capacity. To avoid having a highly complex system, few water availability thresholds should exist in the entire system. Implementation of the Regional Master Plan is guided by a Land Use Capability Map that identifies geographic "zones" based on a comprehensive evaluation of resource constraints and development opportunity. The Land Use Capability Map identifies those resource constrained lands where development should be limited, and as such, where it is appropriate to reserve more water for ecosystem function in order to maintain ecological value. Therefore, the thresholds established in the calculation of Ground Water Availability are determined based on the corresponding zone of the Land Use Capability Map.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/02d07b3dbbcd46d2b2d6a284ec72a4b2_1engNew Jersey Geographic Information Network (NJGIN) Open Data PortalPublicNet Water Availability by Subwatershed Update [New Jersey]Web servicesNew JerseyLast Modified: 2021-03-23