Assessment of groundwater-surface water exchange to support Scatter Creek, Washington baseflow
Scatter Creek, a tributary to the Chehalis River, WA, experiences summer conditions that threaten native fish populations. Each year, parts of Scatter Creek go dry. Dry stretches of stream disconnect the habitat, so that fish can’t move upstream and downstream.
Some of the water flowing through streams may seep into the ground and enter aquifers, meaning that the water is lost from the stream. The remaining water in the stream can get very warm. Salmon and other stream-dwelling species need cold water to survive.
Scatter Creek has the potential to contribute cold water to the mainstem Chehalis to help sustain fish. Groups working to restore the Chehalis Watershed need information about where and when Scatter Creek goes dry, as well as where and how much of its water is lost to the ground.
Objectives
This project will provide information to resource managers to help guide restoration of the basin to improve instream conditions for resident fish. The project’s objectives are to:
- Estimate minimum and maximum extents of intermittent reaches using aerial imagery analysis and field surveys.
- Map the occurrence and magnitude of groundwater-discharge zones during wet and dry seasons in Scatter Creek using vertical and longitudinal thermal profiling techniques.
Approach
Mapping When and Where Streams Go Dry
USGS scientists are visiting several locations along Scatter Creek to determine when and where the stream goes dry. Locations are visited twice a month during the summer months and once a month during the winter, from 2025 to 2026. During visits, the field team will observe record whether a stream location is flowing or dry using the USGS’s FLOwPER data collection platform. They will also measure the water temperature.
We are working with landowners in the Scatter Creek watershed to obtain stream access for these visits. If you are a landowner in the area and want to learn more about participating in this study, please contact Rich Sheibley.
We are also using aerial images and remote sensing to see how wet and dry areas along Scatter Creek have changed over time. We will map where the stream has flowed consistently and where it is less consistent.
Using Temperature to Monitor Groundwater and Surface Water Exchange
We are measuring the above- and below-ground water temperatures to understand when and where groundwater and surface water interact. Groundwater is typically cooler than surface water, so temperature can be used to distinguish between the two.
Temperature data will allow us to estimate groundwater-surface water exchange in the Scatter Creek basin using two approaches:
- Longitudinal profiles of surface water temperature measured during summer low-flow will show locations along the stream that are more influenced by groundwater.
- Monitoring and modeling vertical temperature profiles of the streambed will provide details about how surface water and groundwater mix.
Scatter Creek, a tributary to the Chehalis River, WA, experiences summer conditions that threaten native fish populations. Each year, parts of Scatter Creek go dry. Dry stretches of stream disconnect the habitat, so that fish can’t move upstream and downstream.
Some of the water flowing through streams may seep into the ground and enter aquifers, meaning that the water is lost from the stream. The remaining water in the stream can get very warm. Salmon and other stream-dwelling species need cold water to survive.
Scatter Creek has the potential to contribute cold water to the mainstem Chehalis to help sustain fish. Groups working to restore the Chehalis Watershed need information about where and when Scatter Creek goes dry, as well as where and how much of its water is lost to the ground.
Objectives
This project will provide information to resource managers to help guide restoration of the basin to improve instream conditions for resident fish. The project’s objectives are to:
- Estimate minimum and maximum extents of intermittent reaches using aerial imagery analysis and field surveys.
- Map the occurrence and magnitude of groundwater-discharge zones during wet and dry seasons in Scatter Creek using vertical and longitudinal thermal profiling techniques.
Approach
Mapping When and Where Streams Go Dry
USGS scientists are visiting several locations along Scatter Creek to determine when and where the stream goes dry. Locations are visited twice a month during the summer months and once a month during the winter, from 2025 to 2026. During visits, the field team will observe record whether a stream location is flowing or dry using the USGS’s FLOwPER data collection platform. They will also measure the water temperature.
We are working with landowners in the Scatter Creek watershed to obtain stream access for these visits. If you are a landowner in the area and want to learn more about participating in this study, please contact Rich Sheibley.
We are also using aerial images and remote sensing to see how wet and dry areas along Scatter Creek have changed over time. We will map where the stream has flowed consistently and where it is less consistent.
Using Temperature to Monitor Groundwater and Surface Water Exchange
We are measuring the above- and below-ground water temperatures to understand when and where groundwater and surface water interact. Groundwater is typically cooler than surface water, so temperature can be used to distinguish between the two.
Temperature data will allow us to estimate groundwater-surface water exchange in the Scatter Creek basin using two approaches:
- Longitudinal profiles of surface water temperature measured during summer low-flow will show locations along the stream that are more influenced by groundwater.
- Monitoring and modeling vertical temperature profiles of the streambed will provide details about how surface water and groundwater mix.