Special-Status Species Surveys

Ventura River Steelhead Habitat Assessment, Ventura, California

Ventura River Steelhead Habitat Assessment, Ventura, California
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Project Name: Ventura River Steelhead Habitat Assessment, Ventura, California
Services: Special Status Species Survey
Client: Hopkins Groundwater Consultants (under contract to the City of Ventura)

Padre conducted a steelhead habitat assessment as part of a surface water/groundwater interaction study conducted within the City of Ventura’s water well field at Foster Park. Padre biologists utilized the rainbow trout Habitat Suitability Index (HSI) model developed by the U.S. Fish and Wildlife Service, as modified by Thomas R. Payne & Associates. The study reach was classified according to the California Department of Fish and Game Level II stream habitat classification system, which identified 11 percent pools, 43 percent runs and 46 percent riffles within the 8,850 foot-long study reach. Six sample units were randomly selected from each of three habitat types, yielding 18 sample units (6 pools, 6 runs, and 6 riffles). The 18 units were sampled during each of 24 sampling events selected to encompass the dry season decline in surface flow, May to September. Most of the data was collected during periods of normal groundwater pumping by the City (as required to meet seasonal demands). However, groundwater pumping was manipulated prior to several sampling events to observe the effect of groundwater pumping at Foster Park on surface water flow rate and steelhead habitat. The assessment indicated that HSI values for adult steelhead declined drastically as the average water depth over the dry season declined below 25 cm.