CACHE CREEK WATERSHED

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CACHE CREEK WATERSHED

• Watershed Overview
• Physical Description
• Land Uses Present
• Flow Characteristics
• Beneficial Uses
• Point and Non-Point Source Pollutants
• Pollutants Present in Watershed
• Pollution Management Measures

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Physical Description

• Entire watershed approx. 1,200 mi2 in area
• Divided into three sections based on watershed
  topography and shape
• Upper Section
• Encompasses 80 of total watershed
• Three branches (main fork, North Fork, Bear
  Creek)
• Two large water bodies are present (Clear Lake,
  Indian Valley Reservoir)
• Several small communities border Clear Lake

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Physical Description (cont.)

• Middle Section (Capay Valley)
• 16 of total watershed
• No significant tributaries
• Capay Dam (water diversion)
• Sparsely populated
• Lower Section (Sacramento Valley)
• Includes City of Woodland
• Entirely length controlled by levees
• Discharges to Yolo Bypass and Sacramento River

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Cache Creek Watershed
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Land Use Distribution

• Over 70 undeveloped (forest, woodland)
• Approximately 23 agricultural
• Limited to lower Cache Creek and Clear Lake area
• Orchards (most commonly almond)
• Croplands (alfalfa, corn, rice)
• Low density rangeland throughout watershed
• Minor urban/suburban land uses (Woodland, Clear
  Lake communities)

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Flow Characteristics

• Highly variable flow rates (0 to 41,400 cfs)
• Wide seasonal variations reflect lack of flow
  controls
• Flow patterns vary widely within watershed

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Watershed Shape and Flooding

• Watershed shape has significant impact on flood
  potential
• High flood frequency in Capay Valley
• Urban areas along Clear Lake encroach on flood
  plain
• Frequent flooding increases pollutants load from
  runoff

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Beneficial Uses

• Primary Beneficial Uses
• Agricultural supply (canal diversions)
• Groundwater recharge
• Contact/non-contact recreation (rafting, fishing,
  etc)
• Fresh water habitat
• Wildlife Habitat

• Secondary Beneficial Uses
• Industrial service supply (gravel mining)
• Biological habitats of special significance
• Migration of aquatic organisms
• Spawning/ Reproduction

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Point Source Pollutants

• Primary Point Sources (pollutants)
• Precious metal mining (Hg)
• Gravel mining (sediment, physical disturbance)
• Industrial discharges (petroleum HC, synthetic
  organics, metals)
• Landfill discharges (just about anything)
• Wastewater treatment discharges (biostimulants)

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Point Source Pollutants
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Non Point Source Pollutants

• Primary Non-Point Sources (pollutants)
• Human-induced erosion (sediment, physical
  disturbance)
• Agricultural runoff (nitrates, phosphates,
  synthetic organics)
• Animals wastes (biostimulants, fecal coliform)
• Urban runoff (petroleum HC, metals, etc)
• Septic wastes (biostimulants, fecal coliform)
• Improper waste disposal (just about anything)

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Non Point Source Pollutants
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Pollution Management Problems

• Some pollutants may also be introduced by natural
  means
• Sediment discharge up to 3 million tons annually
• Significant area is underlain by bedrock
  containing Hg
• Point and non-point source pollutants may
  interact
• gravel mining increases erosion potential
• erosion may transport mercury to waterways in
  sediment

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Prioritizing Pollutant Impacts

• Pollutant with greatest potential impact is Hg
• detrimental to fish and wildlife
• reduces recreational uses
• limits domestic supply/stock watering uses
• potential groundwater problems
• Sedimentation is a close second
• physical damage to wildlife/fish habitat
• reduced recreational uses (except whitewater)
• increased transport of mine wastes

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Management Strategies

• Integrate point source and non-point source
  management strategies (e.g. Hg mining/runoff)
• Focus on pollutants or sources that can be
  effectively managed (e.g. It is unreasonable to
  apply sedimentation BMPs throughout watershed)
• Educate the public on the risks of non-point
  source pollutants and their role in its management

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Potential Management Measures

• Point Source
• Mine abandonment
• Tailings stabilization
• Gravel mining restrictions
• Habitat restoration
• Industrial discharge permit enforcement

• Non-point Source
• Educational programs
• Permit limits for septic systems in sensitive
  areas
• Construction BMPs in areas with Hg-bedrock
• Flood plain zoning restrictions
• Land set asides for critical groundwater recharge
  areas