Mar
25
Written by:
SuperUser Account
3/25/2011 4:51 PM
A bioassment program requires expected conditions of the benthic macroinvertebrate community to be defined for particular regions of the State. Clearly, one expected condition will not work for all of California. Desert streams do not have the same kind of benthic macroinvertebrates that mountain streams or Central Valley streams have. But, there must also be a limited number of regions in order for the bioassessment program to be manageable.
To define regions, California’s Reference Condition Management Plan (RCMP) followed a well-known and well used approach with historical precedent throughout the United States and within California (i.e. the SWAMP Perennial Streams Assessment) to define specific regions within which to apply the expected conditions. The approach is called the Ecoregion concept where, regional delineations are based on a broad range of geologic, cllimatic and zoogeographic variables. The result of applying the Ecoregion concept to California was 11 regions and include: North Coast, Oak Chaparral, Coastal Chaparral, Interior Chaparral, Sierra, Main Sierra, Central Lahontan, Central Valley, South Coast, Modoc Plateau and Deserts.
The other aspect of defining expected conditions is the degree of disturbance in a watershed. Highly modified areas of the watershed will not be expected to have macroinvertebrate communities that are representative of pristine conditions. In other words, the expected condition will not be the pristine condition.
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