Summary

Description

The freshwater creeks, brackish water sloughs, saltwater marshes and mud flats found on the Humboldt Bay National Refuge provide habitats for at least 110 species of birds, 110 species of fish, 30 species of mammals, and many unique floral species found in and around the bay. The Salmon Creek Unit of the refuge drains a 23.5 square mile watershed managed primarily for timber production and livestock grazing and is recognized as critical habitat for coho salmon, a federally listed species. In 2000 water quality parameters dissolved oxygen, pH, temperature, suspended sediment, turbidity, ammonia, other nutrients, etc. were evaluated in Salmon Creek during high winter and low summer flow conditions and during periods when sensitive life stages of salmon are utilizing the creek. Dissolved oxygen in the upper watershed generally remained above 60 percent of saturation at the Alicia Pass Site and above 90 percent at the Salmon Pass Site. The dissolved oxygen at the lower watershed Refuge site was around 80 percent of saturation, in June, steadily declined to below 50 percent of saturation after August 13, and remained at or below 30 percent from September 2 through October 21. Dissolved oxygen was consistently below 3 mgL from September 14 through October 21 at the Refuge site. After the first major rainstorm 2 inches at the end of October, flows in Salmon Creek increased due to precipitation runoff and dissolved oxygen concentrations returned to levels above 70 percent of saturation. At the Refuge site, the dissolved oxygen concentrations did not meet the numerical criteria for dissolved oxygen objectives as stated in the Water Quality Control Plan for the North Coast Region of California. Total suspended solids increased dramatically in the October 30 water samples after a heavy 2day rainstorm. The highest levels of both BOD5 and TSS were in water samples collected from Little Salmon Creek.