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Compost

Composting is an important component of "closed loop" recycling. We set regulatory standards for composting facilities and compost quality and also provide technical assistance to local governments. By composting yard debris, food scraps, manure, and crop residues, waste can be turned into a valuable resource for farmers, orchardists, and gardeners and reduce the production of greenhouse gases.

Using compost

Compost can be used in landscaping, new construction, and roadside applications. In Washington, there are soil best management practices for using compost when soil is disturbed on developed land.

  • Soils for Salmon - learn about preserving site topsoil and vegetation, reducing compaction, and amending disturbed soils with compost to restore healthy soil functions.
  • Building Soil - Guidelines and Resources for Implementing Soil Quality and Depth - Best management practices for landscape designers, builders, planners, and inspectors to protect and restore soil.
  • Stormwater Management Manuals for Washington - includes field inspection techniques, suppliers of compost, and soil testing laboratories, and specification language in APWA and CSI formats.

Composting at home

A recent study we conducted showed that 50 percent of residential garbage in Washington could have been composted. Most of this material consisted of food (18 percent); and leaves, grass, or prunings (12 percent).

Ecology composting publications

Herbicides

Some herbicides do not break down during the composting process. If contaminated compost is used, the herbicide may still be active and could impact growth of some sensitive plants. If you apply herbicides to your lawn, check the label to see whether you can compost the grass clippings. See the United States Composting Council's Persistent Herbicide FAQ page.

Compost data

From 2010 through 2015, more than a million tons of material was composted at commercial facilities in Washington. These charts show what materials were composted and how much was produced.

A graph showing total materials composted in Washington (in tons). 2010 – 1,074,034; 2011 – 1,004,761; 2012 – 1,089,392; 2013 – 1,141,262; 2014 – 1,167,011; 2015 – 1,197,931

Total materials composted 2010 - 2015.

A graph showing feedstocks composted in Washington, 2010 - 2015.

Feedstocks composted 2010 - 2015. Excel file of chart data.

A chart showing compost produced in Washington (cubic yards). 2010 – 1,402,000; 2011 – 1,197,000; 2012 – 957,000; 2013 – 1,180,000; 2014 – 1,050,000; 2015 – 1,173,000.

Compost produced 2010 - 2015.

A graph showing quantities of food from various sources composted in Washington, 2010 - 2015.

Food composted 2010 - 2015. Excel file of chart data. 

Regulatory resources

Compost facility operator training

Farm and agriculture