Watershed-based water quality management

In response to landscape alteration and increased knowledge of environmental systems, government regulation for the protection of water quality has undergone several adaptations since the landmark Clean Water Act of 1972. Most recently, in 2000, USEPA moved its emphasis from an effluent-based approach to an ambient or watershed-based approach. Prior watershed studies have uncovered relationships between the type of land cover in a watershed and water quality. These studies have generally indicated correlations between urbanized watersheds and degradation of water quality and aquatic ecosystem health. This dissertation is both an extension of these previous studies to the area of water resource policy and regulation, and it is also a re-examination of the land use/land cover-water quality nexus in light of new high resolution landscape mapping for New Jersey based on recently collected aerial color-infrared orthophotography. Information and data for three watershed management areas (WMA) 1, 6, and 17 used for this study were extracted from high resolution land use mapping for 935 subwatershed assessment units in New Jersey and benthic macroinvertebrate sampling results for 775 sites across New Jersey are used to test the hypothesis that water quality assessment and management using a watershed approach is scale dependent. Statistical analysis indicates that water quality measured using a subwatershed assessment unit correlates to large scale land use patterns, but does not explain the variation of water quality with local land use/land cover. Results indicate that the application of spatial analysis techniques can inform the relationship between land use metrics and surface water quality impacts. Additionally, two case studies are examined using the relationships and metrics described above. The first case study provides an analysis of adaptive management for water quality restoration activities. The second case study indicates that recent regulatory changes in New Jersey to limit sewer service areas may be overly broad to ensure effective water quality improvement.