Mid-Coast Biosolids Applications

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.

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.