Protecting Public Health and the Environment.

Municipal Solid Waste Landfills in Idaho

MSWLFs receive solid waste generated by households, which include single- and multiple-family residences, hotels and motels, campgrounds, picnic grounds, and other similar facilities. MSWLFs also may receive other types of solid waste, such as commercial and industrial solid waste. MSWLFs may be publicly or privately owned and operated. In Idaho, publicly owned landfills are frequently owned and operated by county governments. Privately owned MSWLFs are known as commercial solid waste facilities.

In general, provisions of the Idaho Solid Waste Facilities Act (Idaho Code §39-74) apply to all MSWLFs active (receiving waste) after October 9, 1993. The law covers six basic areas: location, operation, design, ground water monitoring and corrective action, closure and postclosure care, and financial assurance.

Summary of MSWLF Regulations


Certain restrictions apply to siting landfills near airports, floodplains, critical habitat areas, wetlands, fault areas and seismic zones, and unstable areas. These restrictions are aimed at deterring interference by birds with aircraft operation, preventing waste from washing out or polluting a protected area, and ensuring design integrity.


Landfills are required to develop programs to keep out regulated hazardous wastes and liquid waste, control explosive gases and stormwater run on/runoff, and comply with federal and state clean air laws and rules. In addition, to prevent the spread of disease by vectors, each day's waste must be covered. Procedures to restrict unauthorized access and prevent illegal dumping also must be in place.


Protection of ground water is the primary goal of various design standards prescribed by law, including use of liners to prevent leachate from seeping into the soil. Design standards ensure that disposal will not threaten endangered species, surface waters, and floodplains.

Ground Water Monitoring and Corrective Action

The law requires MSWLFs disposing of more than 20 tons per day to install monitoring systems to detect ground water contamination. Sampling and analysis must be conducted periodically as well. If ground water becomes contaminated, it must be cleaned up to approved levels.

MSWLFs disposing of less than 20 tons per day based on an annual average and no evidence of ground water contamination are exempt from ground water monitoring and liner and leachate collection requirements. To meet this exemption, the landfill must serve a community that experiences an annual interruption of at least 3 consecutive months of surface transportation that prevents access to a regional waste management facility or a community that has no practicable waste management alternative. In addition, the landfill must be located in an area that annually receives less than or equal to 25 inches of precipitation.

Closure and Postclosure

When a landfill stops accepting waste, it must be closed in a way that will prevent problems in the future. For example, the final cover must be designed to keep liquid away from buried waste. In addition, the landfill must continue to be monitored for 30 years after closure to ensure that the unit is not leaking.

Financial Assurance

Landfills must demonstrate that they have the financial means to cover closure, postclosure maintenance, cleanups, and other possible environmental problems in the future.

Certification Requirements

Existing MSWLFs in Idaho must be certified in compliance with all MSWLF regulations. New MSWLFs or existing MSWLFs wishing to expand their operations must apply to DEQ for site certification. The public must be notified and given ample opportunity to comment. Commercial solid waste facilities also are required to apply for review by a site review panel and pay a site license fee of not more than $7,500 to cover the cost of reviewing the site license application. Responsibility for approving or disapproving proposed design, operation, and closure plans is shared by DEQ and the seven public health districts in Idaho.