Map showing the study area for an investigation modeling the hydraulic and water-quality habitat suitability for macrophytes in the middle Snake River, south-central Idaho.
Modeling the Hydraulic and Water-Quality Habitat Suitability for Macrophytes in the Middle Snake River, South-Central Idaho
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By Idaho Water Science Center
January 24, 2020
Rooted aquatic plants (macrophytes) are essential components of freshwater ecosystems. Macrophyte beds provide shelter for fish and other aquatic life. Their leaves and stems also provide algae with surfaces to colonize, which, in turn, drives the aquatic food webs and dissolved oxygen cycles. However, too much of a good thing can create problems. When growth conditions are favorable, macrophytes and their attached algae can create dense mats that are a nuisance for recreationists.
In July 2019, the USGS began a study of the hydraulic and water-quality characteristics of the middle Snake River to help stakeholders and resource managers better understand factors controlling macrophyte growth. We are conducting the study in cooperation with the Idaho Department of Water Resources (IDWR), the Idaho Department of Environmental Quality (IDEQ), and Idaho Power Company (IPC). The study is focused on the Crystal Springs reach of the Snake River because previous studies found that this area was particularly prone to abundant macrophyte growth.
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Previous studies found that macrophytes were scarce when water velocities exceeded about 3 feet per second or where water depths were greater than about 6 feet. However, these findings posed additional research questions that our study hopes to address:
- For a given flow condition (cubic feet per second (cfs) recorded at a nearby USGS streamgage, what would the velocity profile look like throughout the study area? What about the depth profile?
- Under different water-year scenarios, what portion of the growing season would be expected to be favorable for abundant macrophyte growth?
- What is the duration of flow exceeding 1 meter per second and/or depths greater than 2 meters needed to affect macrophyte growth?
These “what if” sorts of questions cannot be addressed solely through monitoring, so we are taking an approach that combines monitoring and modeling.
The primary objectives of this study include:
- mapping the extent of macrophyte beds within the Crystal Springs reach of the mid-Snake River;
- developing a two-dimensional hydraulic model to simulate the streamflow and provide a daily summary for the depth and velocity within the study reach, and
- developing an integrated macrophyte habitat suitability model to help resource managers relate streamflow and water quality conditions to limiting conditions for macrophyte beds.
The project was planned as a three-year effort in the hopes of being able to measure hydraulic conditions under a wide range of flow conditions. Progress updates will be provided through meetings of the Middle Snake Watershed Advisory Group.
The folloiwng multimedia items are associated with this study.
Study area map for Middle Snake River Macrophyte Habitat Suitability
Map showing the study area for an investigation modeling the hydraulic and water-quality habitat suitability for macrophytes in the middle Snake River, south-central Idaho.
Rooted aquatic plants (macrophytes) are essential components of freshwater ecosystems. Macrophyte beds provide shelter for fish and other aquatic life. Their leaves and stems also provide algae with surfaces to colonize, which, in turn, drives the aquatic food webs and dissolved oxygen cycles. However, too much of a good thing can create problems. When growth conditions are favorable, macrophytes and their attached algae can create dense mats that are a nuisance for recreationists.
In July 2019, the USGS began a study of the hydraulic and water-quality characteristics of the middle Snake River to help stakeholders and resource managers better understand factors controlling macrophyte growth. We are conducting the study in cooperation with the Idaho Department of Water Resources (IDWR), the Idaho Department of Environmental Quality (IDEQ), and Idaho Power Company (IPC). The study is focused on the Crystal Springs reach of the Snake River because previous studies found that this area was particularly prone to abundant macrophyte growth.
Sources/Usage: Public Domain. View Media Details
Previous studies found that macrophytes were scarce when water velocities exceeded about 3 feet per second or where water depths were greater than about 6 feet. However, these findings posed additional research questions that our study hopes to address:
- For a given flow condition (cubic feet per second (cfs) recorded at a nearby USGS streamgage, what would the velocity profile look like throughout the study area? What about the depth profile?
- Under different water-year scenarios, what portion of the growing season would be expected to be favorable for abundant macrophyte growth?
- What is the duration of flow exceeding 1 meter per second and/or depths greater than 2 meters needed to affect macrophyte growth?
These “what if” sorts of questions cannot be addressed solely through monitoring, so we are taking an approach that combines monitoring and modeling.
The primary objectives of this study include:
- mapping the extent of macrophyte beds within the Crystal Springs reach of the mid-Snake River;
- developing a two-dimensional hydraulic model to simulate the streamflow and provide a daily summary for the depth and velocity within the study reach, and
- developing an integrated macrophyte habitat suitability model to help resource managers relate streamflow and water quality conditions to limiting conditions for macrophyte beds.
The project was planned as a three-year effort in the hopes of being able to measure hydraulic conditions under a wide range of flow conditions. Progress updates will be provided through meetings of the Middle Snake Watershed Advisory Group.
The folloiwng multimedia items are associated with this study.
Study area map for Middle Snake River Macrophyte Habitat Suitability
Map showing the study area for an investigation modeling the hydraulic and water-quality habitat suitability for macrophytes in the middle Snake River, south-central Idaho.
Map showing the study area for an investigation modeling the hydraulic and water-quality habitat suitability for macrophytes in the middle Snake River, south-central Idaho.