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Taken from: Knopp, C. 1993. Testing Indices of Cold Water Fish Habitat. Final Report for Development of Techniques for Measuring Beneficial Use Protection and Inclusion into the North Coast Region's Basin Plan by Amendment of the.....Activities, September 18, 1990. North Coast Regional Water Quality Control Board in cooperation with California Department of Forestry. 57 pp.

Knopp's Disturbance Conditions

"Index watersheds, drainages with no human disturbance history or little disturbance within the past 40 years and no evidence of residual erosion or instability due to past human activity. The term "Index" was used instead of "control" to distinguish these reaches from truly undisturbed watersheds. The Index category represented the least disturbed watersheds available and are believed to exhibit similar habitat structure to true controls in most instances. Exceptions became apparent and are noted in the report.

Open roads normally disqualified a reach for inclusion in the Index category, however, exceptions were made on a case by case basis, if the road was unlikely to affect fish habitat. Index reaches were additionally split into Index reaches with no previous management (Index No), and reaches with historic management, greater than 40 years old (Index Yes). This subdivision was not part of the original design. The Results Section displays the two subdivisions, as well as the three original categories. The Index category  was composed of 18 reaches; 12 ‘Index No’ and 6 ‘Index Yes’.

Moderately Disturbed watersheds, drainages with recent management but with good protection of stream courses, (predominantly undisturbed buffers approximately 100 feet or more wide on each side of perennial water courses, minimal road encroachment on the riparian area), high and mid-slope road locations, and avoidance of unstable areas. Timber harvest operations reflected predominantly cable systems. Twenty one ‘Moderate’ reaches were sampled.

Highly Disturbed watersheds, drainages that exhibited large areas of disturbed soil, unpaved, low slope roads, inconsistent or poor stream course protection, and inconsistent avoidance of unstable terrain. Twenty one ‘High’ reaches were sampled. "

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