Overview
Since late summer of 2023, DEQ has been coordinating with Governor Kotek's office, Department of Geological and Mining Industry, Oregon Health Authority and Oregon Water Resources Department to address groundwater issues in Crook County.
Private well owners north of the city of Prineville have submitted concerns to multiple state agencies about their well water quality, including concerns for potential impacts on human health. The reports include concerns about drinking water quality and its impact on their health, household pipes, appliances and suitability for use by livestock and animals.
DEQ's Top Priorities
To adequately investigate groundwater issues in Crook County, DEQ's priorities are to oversee Knife River's groundwater investigation in partnership with DOGAMI. Additionally, DEQ will continue to support OHA as they complete their public health consultation.
Domestic Well Sampling
Sampling domestic drinking water wells is an important first step in addressing water quality issues. DEQ hired an environmental consultant, Maul Foster and Alongi, to sample private drinking water wells in Crook County. The purpose of the domestic well water sampling was not to identify the source of any contaminants found, but to provide homeowners with drinking water quality information, and to provide the OHA with initial data to develop an area-wide public health consultation.
Fall 2024 and Spring 2025 Domestic Well Sampling
In the Fall of 2024, MFA collected samples from 55 private wells over a two-week period. In the Spring of 2025, MFA collected samples from 58 private wells, 52 of which were also sampled in the Fall of 2024. After each round of sampling, OHA notified individual households of results via email.
While EPA has established maximum contaminant levels to protect the public against contaminants that present a risk to human health and secondary maximum contaminant levels for aesthetic considerations, such as scaling, taste and odor, that are not considered to present a risk to human health, these enforceable standards are for public water systems only. The quality and safety of drinking water from private domestic wells are not regulated by the Federal or State Government.
The combined results from the domestic well sampling showed the following:
Read a summary memo
Read the full results and report
Regional Sampling and Analysis Plan
DEQ requires more data to understand what is causing elevated manganese concentrations in groundwater in the region. In collaboration with EPA, DOGAMI, OHA, and OWRD, DEQ has developed a larger comprehensive Sampling and Analysis Plan. If funded, this plan would provide further information about manganese distribution and groundwater flow patterns in the area, while also gathering information to evaluate potential sources of any contamination found in the groundwater.
Knife River Woodward Mine
DEQ and DOGAMI worked collaboratively to request that Knife River Corporation conduct a Groundwater Investigation at the Knife River Woodward Mine. This work, which led to a sampling and analysis plan development, began in October 2024 and was in response to potential water quality impacts in nearby domestic wells. The agencies directed Knife River to conduct a groundwater assessment to evaluate whether mining operations are causing or contributing to groundwater contamination leaving the site. The sampling and analysis plan was conditionally approved by the agencies on July 30, 2025 and Knife River has a deliverable for the remaining items due by Aug. 29, 2025. This conditional approval will allow for the installation of new monitoring wells and the collection of groundwater quality data in the third quarter of 2025 to continue to assess groundwater conditions at the site.
Read
the approved Knife River Groundwater Investigation Sampling and Analysis Plan.