Manure Management and Water Quality

Livestock manure contains bacteria, nitrogen, ammonia, and phosphates. When rain falls on manure, these contaminants can be carried to local waterways by rainwater runoff.

Horse portrait

Many of the County’s creeks and rivers contain fecal coliform bacteria from both human and animal waste. Its presence is an indicator that more harmful bacteria that cause dysentery, hepatitis, and giardia, are likely also present in local creeks.

Excess amounts of nitrogen and phosphorous cause algae blooms which produce toxins dangerous to humans, livestock, and marine life. These nutrients result in dead zones, or areas that lack the amount of oxygen needed to sustain wildlife such as fish, crabs, and sea otters.

When these pollutants enter our waterways, they pose a threat to people, pets, and livestock.

Causes of Manure Polluted Runoff

  • Improper manure stockpiling
  • Manure exposure to surface water runoff
  • Lack of vegetation in pastures

Enforcement of Manure Polluted Runoff 

State law and local regulations prohibit discharges of manure-laden water to the storm drain system and into creeks and rivers. State law requires the County of Santa Clara to prevent the discharge of pollutants, including manure and manure-laden runoff to public waterways.

  • County Code Section B.11.5 prohibits any non-stormwater discharge to public waterways. This means that the discharge of any polluted runoff from your property into the storm drain or creek is subject to enforcement and penalties by the County.
  • County Code Section A.1-34 defines a public nuisance as any use or condition of property that is unsafe to public health. Manure conditions that result in excessive odor, flies and other vermin, or that release bacteria-laden runoff are nuisance conditions.
  • County Code Chapter IX defines manure as refuse and prohibits production or storage of refuse in a manner that represents a threat to the public or environmental health.

Manure Management Plans

The Department of Environmental Health Solid Waste Program reviews Manure Management Plans which are required for commercial stables larger than 2.5 acres (see Municipal Code §4.10.360). Your plan should include manure management techniques (composting, removal, spreading, etc.), vermin control, and hazardous health or nuisance conditions.

Responsible management of manure protects the environment and prevents nuisances. Some best management practices include: 

  • Clean-up manure on a regular basis, especially during the wet season.
  • Compost manure to reduce volume, pests, and carbon emissions, and to create an optimum nutrient source for your soil.
  • Store manure and compost piles on a flat, dry, and impermeable surface. Make sure your storage area is not near a creek or storm drain nor at the top of a hill. Keep storage piles contained and covered at all times.
  • Spread manure over pasture surfaces in a layer no thicker than 1 inch to increase vegetation productivity. Do not spread near creeks, ditches, or other waterways.
  • Dispose of manure as a recyclable waste at a commercial compost site, or as trash at most landfills every seven days.

Responsible Land Management Practices

  • Cover all storage piles (manure, dirt, bedding, etc.) and equipment with tarps or plastic throughout the year.
  • Surround manure piles with barriers to contain pollutants.
  • Divert any contaminated water away from creeks and storm drains and toward vegetated buffer areas.
  • Use vegetation to your advantage by keeping pastures green to reduce erosion and runoff.
  • Compost to reduce manure volume.


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