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Chapter 6 -- Changes and Trends in Stream Habitat and Fisheries (continued)

Sediment Production Trends

Over centuries, stream channels in northwestern California have existed in a "punctuated equilibrium" : periods of relative stability and recovery broken by periodic large perturbations that increase sediment loads several fold (McCain et al. 1995). Beyond this outline of the big picture, we don't know much about baseline sediment loads. We do know that hydraulic mining occurred from the 1860s to the 1930s, and this caused increased sediment loads. Further research on the extent and duration of hydraulic mining might help us understand present stream habitat conditions. Sediment loads also increased due to floods in 1955 and 1964. In addition to increasing total sediment load, natural and human-caused disturbances typically increase the proportion of fine sediments.

According to some long-time fishermen, the number of deep pools on the South Fork, the lower Smith River, and the Smith River estuary has decreased since the 1960s (Waldvogel 1996). This suggests that, prior to the mid-century floods, sediment loads were lower.

Over the long-term, stream sediment loads may decrease due to reduced road building on the National Recreation Area. However, any presumed long-term recovery trends can be obscured in the short-term by sediment inputs caused by severe storms and high flows. Likewise, forest fires can contribute to sudden reversals in recovery processes. For a more complete discussion of trends in sediment loads see McCain et al. (1995) and for discussion of increases in sediment following logging operations see California Department of Fish and Game (1980).

Mining remains a source of sediment to the Smith River. Many areas disturbed by mining are actively eroding (McCain et al. 1995). Although new mining claims are prohibited by the Smith River NRA Act, existing mining claims, such as the Cal-Nickel claim, are still valid. Cal-Nickel Corporation has expressed renewed interest in mining on Gasquet Mountain (Mike Furniss personal communication 1997). In 1996, the Forest Service formulated administrative rules concerning mining in the NRA. Major provisions are that:

  • Reclamation should be concurrent with mining operations.
  • Operation plans are required for proposed suction dredging and sluice mining operations.
  • Suspension of mining operations can be ordered when necessary to protect resources.
  • Existing rights must be proved through legal documentation (USFS 1996).

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