Impacts to Humboldt Bay NWR From Forestry and Dairy Activities in the Salmon Creek Watershed
Humboldt Bay, in Humboldt County on the north coast of California The freshwater creeks, brackish water sloughs, saltwater marshes and mud flats found on the Humboldt Bay National Wildlife Refuge provide habitats for hundreds of species of birds, fish, mammals, and unique flora.  Salmon Creek located on South Humboldt Bay drains a 23.5 square mile watershed managed primarily for timber production and livestock grazing. Located within the upper watershed of Salmon Creek, 11 miles east of Humboldt Bay, is the Headwaters Forest Preserve, an old-growth redwood forest. Agricultural activities (primarily forestry, dairies, and cattle ranches) within the Salmon Creek watershed contribute contaminants to Salmon Creek. Adult Male Coho ChinookThe levels of contaminants in Salmon Creek have been high enough to make the creek a highly turbid and foul-smelling public nuisance during summer low flow periods.  A former Refuge manager also observed that the creek water was often white in color.  In past years, it is suspected that the poor water quality in Salmon Creek resulted in the deaths of juvenile salmonids found in the creek during the summer months. Fish monitoring conducted by the U.S. Fish and Wildlife Service between 1989 and 1991 documented coho (Oncorhynchus kisutch), chinook (Oncorhynchus tshawytscha) and steelhead (Salmo gairdneri) salmon in Salmon Creek.

Man Demonstrating Datasonde-3 ProbeMethods: Datasonde-3 multi-parameter data logging water quality instruments were deployed in Salmon Creek at the refuge beginning June 15, 2000, and in Salmon Creek at the Headwaters, Alicia Pass site beginning July 22, 2000.   Water quality monitoring at the Alicia Pass was discontinued on September 21, due to low water levels in Salmon Creek.  Water quality monitoring began at the Salmon Pass site on October 4. Temperature, dissolved oxygen, specific conductivity, and pH were the main parameters measured.

Dairy OperationResults and Discussion: The dairy operation adjacent to the refuge which, at various times in the past, was introducing cow feces and urine directly to Salmon Creek upstream of the refuge ceased operations at some point during the winter of 1999-2000.  Dairy operations are regulated and inspected by the State of California, Regional Water Quality Control Boards (RWQCB).  After an inspection by North Coast RWQCB staff it became evident that the necessary improvements to the dairy facilities, which would bring the operation into compliance with State regulations, would not be economically feasible.  The Standing Water at Dairy refuge is currently working to acquire the dairy property and pastureland.  All data collected for this study has been collected after the dairy adjacent to the Refuge was closed. However, there may be residual effects to Salmon Creek water quality due to contaminants from the dairy and continuing effects from the other contaminant sources in the watershed (other dairies and forestry). Dissolved oxygen was consistently below 3 mg/L from September 14 through October 21 at the refuge.  The water quality in Salmon Creek decreases from the Headwaters to the refuge.  However, the low dissolved oxygen levels at the refuge are not explained by the dry season values in Salmon Creek water samples. Ammonia was not detected in any water sample collected from Salmon Creek.  Total suspended solids increased dramatically in the October 30 water samples after a heavy 2 day rainstorm.

Juvenile ChinookLearn More by Reading the Full Report: Henderson, J., Impacts to Humboldt Bay NWR from Forestry and Dairy Activities in the Salmon Creek Watershed, USFWS, Div. of Env. Contaminants, Sacramento, CA. 2001.

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