Countywide Summary of Results


Stream Protection Strategy - Countywide Summary of Results

Upon completion of the Stream Protection Strategy Baseline Study, every county watershed was given a management category designation based on both the composite biological ranking and future development potential (estimated imperviousness). The management categories and percentage of watersheds designated are as follows:

Watershed Protection Area (31.5 percent)
Watershed Restoration Area Level I (7.2 percent)
Watershed Restoration Area Level II (61.3 percent)

These categories are intended for use as watershed planning tools and are characterized by a set of goals and strategy recommendations that best suit the respective stream environments given current subwatershed development patterns, likely future development patterns, and biological condition.

 

Management Categories

A numeric ranking of overall quality was generated for each of the Stream Protection Strategy monitoring sites within the county. These rankings (see above charts) were based on the numeric scores of four primary components of stream/watershed condition: 1) Index of Biotic Integrity incorporating scores from the benthic macroinvertebrate analysis; 2) fish taxa richness (number of distinct species present); 3) a general evaluation of the watershed habitat features (including vegetation, instream features and riparian zone habitat); and 4) percent impervious area cover.

Index of Biotic Integrity Ratings Fish Abundance Ratings Habitat Assessment Rankings

The results of the baseline assessment highlight a strong link between level of development, as reflected by levels of imperviousness, and measures of stream quality. Systems of high biological integrity are typically found in largely undeveloped or lower density developed watersheds. Conversely, the most degraded streams are found in areas of more intense development and in older areas with inadequate stormwater management controls, as depicted in the a map below. Research shows that at levels of 10-20 percent impervious cover, habitat quality and biological integrity in stream systems are significantly diminished unless the effects can be mitigated with effective stormwater controls.

Stream Protection Strategy Sites and Imperviousness Cover


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