Information provided through long-term stream-gauge monitoring is critical to understanding patterns in watershed health related to disturbance and/or recovery. 

For 15 years the Coos Watershed Association (CoosWA) has operated streamflow gauging stations to monitor water level and volumetric discharge (flow) on local streams. What started as 3 gauging stations on the East Fork Millicoma River has since grown into a robust network of 9 stations that record data on variables ranging from streamflow to photosynthetic active radiation (PAR). There are 9 other stream gauges outside of CoosWA’s network operating south of the Umpqua River (18 stations total). Data collected at CoosWA’s stream gauge stations can be broadly divided in to three types of monitoring: hydrological, meteorological, and water quality. The information these metrics provide is a precursor to understanding a broad range of watershed conditions and the ability of aquatic habitats to respond to perturbations, whether natural, anthropogenic, or the result of restoration actions.

To see data from our stream gauges (updated every 15 minutes) click here!

Freelin water velocity testing

Hydrological Monitoring

Hydrological monitoring refers to data collection that helps us better understand the movement and distribution of water in local streams. CoosWA currently operates and maintains 9 stream gauges on the following streams: South Fork Coos, West and East Fork Millicoma, Tioga, Winchester, Tenmile, Eel, Whiskey Run and Marlow. Of these stream gauges, data from 5 are uploaded every 15 minutes on our website. Water level and volumetric discharge data from the gauges are used to create a “ratings curve”, or the correlation of measured water surface elevation with stream gauges (Kennedy, 1984). 

gauge house

Meteorological Monitoring

Meteorological monitoring involves collecting data that is used to understand local weather conditions.  CoosWA operates 2 automated weather stations in conjunction with stream gauges located on the West Fork Millicoma River (2004-2016) and Marlow Creek (2003-2016). A 3rd station collected data on the South Fork Coos River from 2003-2014. The West Fork Millicoma and South Fork Coos stations also collect rainfall data (2014-2016). Our data is unique in that it is situated to provide direct correlations with stream gauging stations, it is far enough inland to avoid orographic/rain shadow precipitation, and it is well placed to establish rainfall-runoff relationships.

temperature sensor

Water Quality Monitoring

CoosWA’s primary method of water quality monitoring involves sensor installations to measure water temperature (shown to the left) and turbidity on Marlow, West and East Fork, Winchester streams. Willanch and Tioga Creeks measure water temperature only. While water quality at these sites is assessed annually, similar equipment may also be used to provide water quality monitoring pre and post restoration projects. Data from water quality sensors and integrated samplers, as well as data from hydrological and meteorological monitoring, provide important inflow context for other permanent water quality networks based in the estuary and bay.


Monitoring trends in water levels, flow, and quality is not new to Coos Bay. From 1954 – 1981 the USGS operated a gauging station on the West Fork Millicoma River, providing the region with 27 years of valuable data on system conditions. Re-installing a gauging station on the West Fork is one of multiple historic monitoring efforts that CoosWA has replicated over the years to in order to build a more complete set of data that captures long-term trends and increases the accuracy of water resource predictions for the area. Longevity in hydrological, meteorological, and water quality monitoring is critical not only to effectively manage populations such as coho salmon but also to better understand watershed level ecosystem processes, particularly in the face of climate change.

Project Contact

Freelin Reasor

t: 541-888-5922 ex. 307