Water Quality Programs

DEQ's biosolids program is implemented through one coordinator position located at the headquarter's office in Portland and various regional staff throughout the state. DEQ biosolids staff meet regularly throughout the year to discuss implementation issues and to improve program efficiency and consistency.


University assistance

Oregon State University assists in biosolids program implementation through their research programs and technical assistance provided by local extension agents on soil, nutrient and crop management. OSU soil scientists have collaborated with DEQ, the Oregon Association of Clean Water Agencies, and the Northwest Biosolids Management Association to produce technical guidance and documents, and to provide training on the land application of biosolids.

Washington State University and the University of Washington are also actively involved with biosolids research programs in the Pacific Northwest and provide technical assistance with regards to the beneficial use of biosolids.


Compliance assurance

DEQ inspections and data review

DEQ's regional staff is responsible for assuring that wastewater treatment facilities and biosolids operations are in compliance with pertinent state and federal regulations, which are stated as conditions in a water quality permit, biosolids management plan, and site authorization letters. Monitoring and reporting requirements provide process and operational data which is reviewed and evaluated for compliance purposes. Regional staff also conduct inspections of wastewater treatment facilities, biosolids and septage operations, and sites proposed for land application.

Public concerns

In an effort to assure effective compliance, DEQ responds to public concerns about potential biosolids program management problems. These problems may be associated with land application activities at a particular site, including odors, runoff, or timing of application. These concerns are often discussed with the responsible facility, including what corrective action may be needed. Any concerns regarding potential problems with biosolids activities should be directed to the nearest DEQ regional office.

Land application

Beneficial use

Biosolids beneficially used are land applied at agronomic rates that benefit soil quality and the growth of crops. Biosolids can also be used for enhancing vegetative growth on reclamation sites and on USDA Conservation Reserve Program (CRP) lands at greater than agronomic rates. These sites are reviewed on a case-by-case basis and appropriate agronomic rates are determined.

Land application sites

All land application sites must be authorized in writing by DEQ prior to use. DEQ regional water quality staff will visit a site to ensure site characteristics allow for land application. Sensitive areas, setbacks, drinking water wells, and unique site features all need to be identified. Many sites are used seasonally depending on climatic conditions, where the site is geographically located, and the site use. The crop management system is also important. Field accessibility, frequency of biosolids application, irrigation practices, nutrients available from the biosolids, and application methods need to be considered. Crop management factors such as type of crop, timing of crop harvest, waiting periods for crop use (e.g., 30 days for grazing), nutrient management, water management, and conservation practices will also affect the use of biosolids.

Agronomic rate

The quantity and quality of biosolids are interrelated with regards to how biosolids are used in land application. Agronomic rate refers to an application rate that provides the nitrogen needs for a given crop or vegetation and that will minimize the amount of nitrogen in the biosolids that passes below the root zone of the crop or vegetation to groundwater. The nutrient content of biosolids will vary depending on the primary source of the biosolids, the age of the biosolids, the method of processing prior to land application, and the method of application. For dedicated application sites used year after year, DEQ requires that soils be sampled every third year for residual nitrate nitrogen according to protocols published by OSU and the American Society of Agronomy. This testing is used to assess the impact of all fertilizer nitrogen, including that from biosolids.

Biosolids quality

There are many different wastewater and biosolids treatment processes that result in a biosolids product with different characteristics. No matter what process is used, the product must meet certain pollutant concentration limits as well as operational standards to control pathogens and reduce the attraction of vectors (e.g., flies, mosquitoes, and other potential disease carrying organisms).

Under federal and state regulations, biosolids are designated as "Class A" or "Class B" depending on the process used to reduce pathogens. More extensive treatment is required for Class A than for Class B, and for each of these classes land application requirements vary. If requirements are met for Class A pathogen reduction, vector control, and the more stringent pollutant concentration limits for metals (Table 3, 40 CFR 503.13), the biosolids are defined as "Exceptional Quality" and are not subject to land application general requirements and management activities. EQ biosolids may generally be used like any other fertilizer or soil amendment product.