Water-quality data from monitoring sites along the Donner und Blitzen River, Oregon, 2024 and 2025

The Donner und Blitzen River is a snowmelt and spring-fed system that is the primary drainage for Steens Mountain in southeastern Oregon. The river flows northward through the Donner und Blitzen Valley within Malheur National Wildlife Refuge before terminating in endorheic Malheur Lake. Within the refuge, water management infrastructure diverts river flow through a network of dams and canals, distributing water across the floodplain through flood irrigation to maintain critical wetland habitats for native and migratory bird species along the Pacific Flyway. This study assessed the effects of water management practices and channelization on the water quality in the Donner und Blitzen River.

In 2024, five continuous water-quality monitoring sites (S1, S2, S3, S4, and S5) were installed along the Donner und Blitzen River within the refuge, with an additional site (S4.5) installed in May 2025. At each site, YSI 6-series water-quality monitors recorded water temperature and turbidity at 30-minute intervals during March-September 2024 and March-September 2025.

During 2024 and 2025, a calibrated YSI 6-series reference water-quality monitor was used to collect discrete point measurements to support and validate continuous monitoring data at sites S1-S5 and to collect supplemental point measurements for longitudinal surveys and canal measurements. Water-quality parameters included water temperature, specific conductance, turbidity, and dissolved oxygen. Reference measurements were collected during visits at the monitoring sites, during longitudinal river surveys conducted upstream of S3 and S5, and at selected locations upstream and downstream of canal return flows between S1 and S3 in 2025.

This data release includes 5 comma-separated values (.csv) files, one Word document, and metadata. The CSV files include 1) site location information and the type of data collected at each site; 2) complete turbidity datasets for S1-S5 for water years 2024 and 2025, which include values filled using correlation-based estimates or linear interpolation; 3) reference monitor water-quality point measurements collected during site visits in 2024 and 2025; 4) reference monitor water-quality data collected during longitudinal river surveys in 2024 and 2025; and 5) reference monitor water-quality point measurements collected at certain sites and upstream and downstream of canal outlets between S1 and S3 in 2025. The Word document provides a method summary of how missing turbidity data were filled in at each site to create the complete turbidity datasets.