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Sediment Information in KRIS Noyo  

KRIS Web Background Pages: Sediment       

The KRIS Noyo project has gathered sediment data from many sources. The City of Fort Bragg provided turbidity data collected at its water pumping station. Gravel quality data was provided by the Mendocino Redwood Company (MRC), the California Department of Forestry (CDF) and from historical California Department of Fish and Game studies. MRC also provided stream cross sections and longitudinal profiles.  Data gathered from nearby streams for a North Coast Regional Water Quality Control Board (NCRWQCB) study of fine sediment in pools (V*) and particle size distribution (Knopp, 1993) are also analyzed in KRIS Noyo. KRIS has incorporated a substantial amount of data from Matthews (1999) Sediment Source Analysis and Preliminary Sediment Budget for the Noyo River. This document is a key element of the U.S. Environmental Protection Agency (EPA) and NCRWQCB joint effort to abate water quality problems through the Total Maximum Daily Load (TMDL) process.  

The Noyo River is being studied for TMDL because it has been declared by State and federal water quality managers to be impaired by sediment. "Sedimentation was determined to be impacting the cold water fishery, a beneficial use of the Noyo River watershed, including the migration, spawning, reproduction, and early development of cold water fish such as coho salmon and steelhead trout. Cold freshwater and estuarine habitats are also designated uses of the Noyo River watershed" (NCRWQCB, 1999). 

The NCRWQCB (1999) set stream habitat goals and water quality standards for sediment inputs and  as part of their TMDL report for the Noyo (see table below). Thresholds for fine sediment less than 0.85 mm, fine sediment less than 6.4 mm and fine sediment in pools (V*) are all used for reference in KRIS Noyo. These thresholds are all explained and defended within the TMDL but appear reasonable given existing information both locally and regionally. For example, the 14% threshold for fines (<0.85 mm) is in conformance with the National Marine Fisheries Service (1996)  guidelines for properly functioning salmon habitat, which set a  limit of 12% fine sediment less than 0.85 mm. McHenry et al. (1994) found that fines less than 0.85 mm were nearly 100% lethal to coho and steelhead eggs when they exceeded 13% within the redd. Barnard (1992) used freeze core sampling in Freshwater Creek, a Humboldt Bay tributary, and  found that sediment less than 1 mm comprised  less than 10% of the samples at most sites.  Fine sediment levels (<1 mm) inside redds did not exceed 13%. The bedrock geology is sandstone and Franciscan, and the watershed had experienced 40-60 years of  rest. 

Below: Taken from NCRWQCB (1999) where it appears as Table 7.

Many charts related to sediment supply and transport, such as the two below, are patterned after Matthews (1999). The discussion about assumptions related to these graphs can be found in the Sediment Source Analysis and Preliminary Sediment Budget for the Noyo River.

Above: The total amount of sediment transported by the Noyo River was calculated by Matthews (1999) from regional data and compared with the amount of sediment dredged from the Noyo Harbor by the Army Corp of Engineers. Most of the regional streams used for the transport estimate were not located on the Mendocino coast and none were proximate to the Noyo River. Matthews estimated that 80% of the sediment transported by the Noyo River was deposited in the estuary and 20% passed into the ocean.

Above: Matthews (1999) estimated sediment yield from mass wasting in the Noyo Basin using aerial photos and found the trends shown above. The earliest photos reviewed by Matthews (from 1942) showed that landslides were predominantly in forests (86%) as opposed to areas recently harvested (within 15 years), while roads triggered no landslides. The railroad bed was responsible for 12% of the mass wasting. With increased timber harvest and road building, the number of landslides in recent timber harvests and those triggered by roads increased substantially.

The Little North Fork Noyo River is particularly well studied with regard to sediment. Burns (1972) found that fine sediment less than 0.8 mm increased from 20% to 31% in that stream between 1966 and 1969, as a result of logging and road construction proximate to the stream. Valentine (1994) measured fine sediment less than 0.85mm and found a mean of 26% across all sites (see graph below). Samples from both eras are compared in KRIS and sediment supply, pool frequency and quality, fine sediment in gravels and land use are all discussed further in Analysis section and in the KRIS data base topics.

Valentine (1994) measured fine sediment (less than 0.85 mm) at five sites in the Little North Fork Noyo River and found levels ranging from 20.8% to 31.2%. These values exceed the NCRWQCB TMDL threshold of 14%, which was set to protect spawning salmonids.

Knopp (1993) measured various stream habitat parameters at 60 stream locations throughout northwestern California and found significant linkage between fine sediment in pools, particle size distribution and watershed disturbance. Knopp's data is used in KRIS because many of the streams studied are in the Mendocino project area. The threshold of 0.27 shown in V* charts is taken from the Noyo TMDL (NCRWQCB, 1999). Although the average percent fines in pools for the regional control streams was actually 0.21, the 0.27 represents fine sediment levels in the North Fork Caspar Creek, which was considered more representative of local geology than the entire north coast regional data set.

The chart above shows the V* values for a dozen streams within the KRIS Mendocino project area. This metric measures the amount of pools filled by fine sediment. Several streams are under the NCRWQCB TMDL target of 0.27.

References

Barnard, 1992. Physical and Chemical Conditions in Coho Salmon (Oncorhynchus kisutch) Spawning Habitat in Freshwater Creek, Northern California. Masters Thesis. Humboldt State University, Arcata, CA. 81 p. plus appendices.

Knopp, C. 1993. Testing Indices of Cold Water Fish Habitat. North Coast Regional water Quality Control Board, Santa Rosa, CA. Cooperatively sponsored by the USDA Forest Service.

Matthews, G. 1999 . Sediment Source Analysis and Preliminary Sediment Budget for the Noyo Rive r . Graham Matthews and Associates, Weaverville, CA. (Contract 68-C7-0018. Work Assignment #0-18.) Prepared for Tetra Tech, Inc. Fairfax, VA.

McHenry, M.L., D.C. Morrill, and E. Currence. 1994 . Spawning Gravel Quality, Watershed Characteristics and Early Life History Survival of Coho Salmon and Steelhead in Five North Olympic Peninsula Watersheds. Port Angeles, WA. 59 pp. without appendices.

National Marine Fisheries Service. 1996. (Table 1 from...) Coastal Salmon Conservation: Working Guidance for Comprehensive Salmon Restoration Initiatives on the Pacific Coast. US Dept. Commer, NOAA. 4 pp.

North Coast Regional Water Quality Control Board. 1999 . Noyo River Total Maximum Daily Load for Sediment. US EPA Region 9, San Francisco, CA. 87 p.