Twenty Mile South Farm

The City of Boise owns and operates a 4225-acre farm on South Cloverdale Road, approximately 20 miles south of Boise. The "Twenty-Mile South Farm" (TMSF), receives the "biosolids" from the City's two main water renewal facilities: Lander Street and West Boise.

Dewatered biosolids are trucked to the site in trailers that hold approximately 30 wet tons per load. The treated biosolids are stored, then applied to fields for growing forage crops that are eventually sold to farmers. The site is managed to comply with all local, state, and federal regulations governing the reuse of biosolids.

Net Zero Energy Building on the farm

In addition to irrigated fields, the TMSF has constructed a new facility which consists of an office building, maintenance shop, parts warehouse, and mechanic shop. This new facility has been designed to receive LEED GOLD certification, in addition to becoming the first commercial zero net energy facility in Idaho. The intent of this upgraded facility is to offset the energy consumed on-site with energy produced on-site, using solar panels, and operating more efficient heating and cooling systems.

In 2014, TMSF received an "Excellence in Biosolids Management" Award from Northwest Biosolids and the Pacific Northwest Clean Water Association. The award recognized TMSF for its significant contributions in implementing a cost-effective and environmentally beneficial biosolids management program. In the 27-year history of the award, Boise was the first recipient from Idaho.

Why Recycle Biosolids?


Biosolids are valuable fertilizer. The biosolids help replenish the soil nutrients that have been removed by the crops grown at the TMSF. With ample amounts of nitrogen, phosphorus, and potassium contained in the biosolids, the City of Boise doesn't have to buy as much commercial fertilizer, resulting in substantial cost savings for the farm. 


The City of Boise directly receives the revenue that is produced by growing high quality crops on the farm land. This revenue is returned to the water renewal fund which helps to keep rates low for City of Boise rate payers.

Less in the Landfill

Biosolids provide organic matter to improve soil structure and help increase water holding capacity. Another added benefit: using biosolids as a soil amendment keeps the product out of the landfill, saving worthwhile landfill space.

Compost at Twenty Mile South Farm


Before 1993

City of Boise administered a land application program whereby local farmers would enter into contracts that would allow liquid biosolids to be applied to private farmland. The parcels located near the West Boise Water Renewal Facility received priority for biosolids applications and the City of Boise applied year-round.


EPA made land application rules more stringent. At the same time, the Treasure Valley was experiencing significant growth. Areas traditionally used for agriculture were being encroached upon by urban development.


City of Boise purchased 2325 acres of farmland for biosolids application and began growing crops: primarily, alfalfa, corn and small grains.

1994 - Present

Over the years, additional acreage was purchased to bring current farm acreage to 4225 acres. The City of Boise owns and operates the entire facility, from the biosolids transport, storage, and application to soil preparation and tillage, to planting and harvesting the crops. The wheat combining and silage corn chopping are completed by outside contractors each season, but the City of Boise performs all other farming duties.

Additional Information


For more information, or to schedule a tour:

(208) 608-7446
TTY: 1-800-377-3529

Compost Questions

For information around the city's compost program, visit Curb It.

Learn more

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