Threats

The Fall River Valley’s Uncertain Future

  1. Large land tracts and historic farms threatened by subdivision and parceling
  2. Water demand  increased for residential, hydropower, agricultural development
  3. Water quality, habitat conditions, fish populations at risk
  4. Over sedimentation in upper River
  5. Invasive aquatic species
  6. Increased pressure on fish and wildlife by recreational users

In 1996, The Central Valley Regional Water Quality Control Board designated the Fall River an impaired waterway due to increased sedimentation caused by both natural and anthropogenic sources.

Upper Fall River Sedimentation

The sources of sedimentation have been studied extensively and tens of thousands of dollars have been spent to successfully stop additional sediment from entering the river. Unfortunately, two to four feet of fine sediment (275,000 cubic yards) still blankets much of the upper river while invasive aquatic plants continue to spread throughout the lower portion of the river.

The long-term impact of excessive sediment and invasive species on the fishery remains uncertain. However, anecdotal evidence from local residents, fishing guides, and landowners suggests that habitat conditions and trout populations in the Fall River continue to deteriorate at an alarming rate.

Equally troubling is the absence of updated baseline data, which could help quantify the effects of these alarming trends on wild trout populations and the overall ecology of the Fall River.

 


Invasive Aquatic Plants

Minimal data exists concerning the stability of wild trout populations, the productivity of the food web, flow conditions, or the impact of land-use patterns on the river. The fish population data that does exist suggests that numbers fluctuate greatly from year to year from approximately 2,000 to 4,000 fish per mile (R. Michael, 1986).

Since 1975, DFG has monitored fish populations at two locations: the “Gas Pipeline” and the “Whipple” reach. DFG monitoring data does not show any significant decline in population numbers although the abundance of trophy trout (14inches) in the monitoring area appears to fluctuate from year to year.

Numerous assumptions exist about the various factors limiting wild trout populations and healthy habitat in the Fall River. Unfortunately, these assumptions originate from research which dates back almost ten years (Fall River Resource Conservation District, 2002) (Tetra Tech Inc, 1998) (Department of Water Resources, 1998).

Consequently, the absence of current scientific data makes it difficult to determine existing conditions or prioritize limiting factors.