Composting at Home and Water Quality

Composting at home is a great way to reduce landfill waste and your carbon footprint. Applying good quality compost to your garden nourishes healthy soil to grow healthy plants with less fertilizer and saves water by reducing the amount you need to irrigate in the summer. But composting at home has the potential to pollute nearby waterways.  Follow these tips to compost at home in a way that protects water quality in your neighborhood. 

Managing your compost to protect water quality

  • Use a contained compost bin.   Buy a commercially produced bin or build your own. Make sure your bin allows air to circulate, keeps your compost contained, and has a cover.  
  • Place your compost bin at least 100 feet away from waterways. Locating your compost away from ditches, creeks, and lakes allows any runoff to soak into the ground instead of flowing into the water with pollutants like phosphorus or nitrogen. Avoid slopes and areas with a lot of rainwater runoff or erosion.
  • Protect your compost from animals. Animals like rats and raccoons are attracted to food scraps in compost. If you don’t have a contained bin, fully bury fruit and vegetable scraps within the pile. Cover your pile to keep animals out.
  • Cover your compost during the wet season. Use a hard lid or weighted tarp to keep the rain out.
  • Get the right mix. The right blend helps ensure your pile will fully compost, which reduces the likelihood of any nutrient runoff. Add approximately two parts brown bulking agents (sawdust, woodchips, straw, etc..) to one part green energy materials (grass clippings, food scraps, garden trimmings, etc..)
Carbon and Nitrogen sources for compost graphic

Using your compost and protecting water quality

  • Sweep up any compost from hard surfaces. Rain can wash compost (and soil) left on driveways and sidewalks into the nearest waterway, polluting the water. 
  • Do not over apply compost. 
  • Apply compost the right way at the right time.
    • Top dress by adding a layer of compost ON TOP of the soil instead of mixing it in.
    • Top dress landscape areas with compost and cover with low phosphorus mulch such as wood chips.  
    • Apply compost to vegetable gardens when planting in the spring.  
    • Apply compost to annual gardens in the early summer after plants are established or in the fall after harvest to help protect the soil from erosion.

Consider using wood chips or other low-phosphorus mulches in landscape beds with shrubs, trees, and other perennials. Wood chips slowly feed the soil, enhance soil health, prevent soil compaction, suppress weeds, and help maintain soil moisture. Use your home compost in vegetable and annual garden beds.

Visit WSU Whatcom County Extension’s website for additional information and resources to help you compost at home.

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