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Mid-Coast Biosolids Applications

DEQ authorizes a number of cities along Oregon’s Mid-Coast to apply biosolids. Below is a list of frequently asked questions and documents associated with the various cities including site authorizations, biosolid management plans and annual reports.

2018 Site authorizations Siletz-Logsden area

DEQ proposed updates to the following site authorizations. Public notice period ended on Friday Dec. 21, 2018. 

Ongoing efforts to study and improve water quality in the Siletz River

Oregon’s Clean Water Act Section 303(d) list identifies multiple waterbodies in the Mid-Coast Basin as impaired in for temperature, bacteria, sedimentations, dissolved oxygen and weeds/algae. DEQ is evaluating potential sources of these impairments. DEQ’s evaluation will consider whether biosolids may contribute to water quality issues. DEQ assembled a local stakeholder advisory committee in 2012 to provide advice to DEQ in developing strategies for water quality improvements as part of the “Mid-Coast Basin Total Maximum Daily Loads.” Please see DEQ’s Mid-Coast Basin page for more information.

Are there groundwater issues in the area caused by biosolids applications?

DEQ reviewed the well logs from Oregon Water Resources Department for the area and limited well data from the real estate transaction database. DEQ does not believe biosolids are affecting groundwater. Most of the wells draw from an aquifer that is in bedrock and under confined conditions, which means the aquifer is largely protected from any potential surface contamination provided the wells have been properly constructed. There is one well closer to the river that is likely influenced by the river but there were no shallow wells documented in the department’s database. In all cases, if the wells are properly constructed, risk of contamination from properly applied biosolids is very low.

Resource documentation


  • Mid-Coast Basin TMDL/Nonpoint Source Program
    David Waltz, 541-687-7345