From the variable grades, an overall grade is created for each reach. This grade reflects a composite score from each of the assessment variables using a weighted average as covered in the table below. If a reach lacked sufficient data for a given variable or metric, that variable or metric was excluded from the grading.
Geomorphology describes how rivers naturally change shape and function over time. Healthy rivers adjust to changes in flow, sediment, and vegetation, supporting habitat, water quality, and floodplain function. Assessing planform and profile dynamics helps identify whether human impacts, such as channelization or land use changes, are affecting river health. The geomorphic condition assessment includes two metrics: planform and profile dynamics.
Planform Dynamics | Profile Dynamics |
|---|---|
50 | 50 |
Planform dynamics refer to the natural lateral or "horizontal" shape and movement of a river, including its meanders, bends, and braided channels. These features create diverse habitats, redistribute sediment, and keep the river connected to its floodplain. Roads, railways, bridges, and agriculture can restrict a river's ability to naturally shift and adjust, reducing habitat diversity and overall river health. Stream reaches are graded based on how much of the reach length shows visible constraints from human development.
Grade | Scale | Description | Explanation |
|---|---|---|---|
A | 90-100 | Optimally functional | Low planform stressors (river has the ability to naturally adjust and has minimal to no anthropogenic impacts from developments and roadways). |
B | 80-89 | Highly functional | Low to moderate planform stressors (river maintains the ability to naturally adjust but is in minimally impacted by anthropogenic impacts from developments and roadways). |
C | 70-79 | Mostly functional | Moderate planform stressors (river's ability to naturally adjust is moderately impacted by anthropogenic impacts from developments and roadways). |
D | 60-69 | Party functional | Moderate to high planform stressors (river's natural ability to adjust is moderately to highly impacted by anthropogenic impacts from developments and roadways). |
F | 50-59 | Dysfunctional | High planform stressors (river's natural ability to adjust has been highly impacted by anthropogenic impacts from developments and roadways). |
N/A | N/A | Not Graded | Not Graded |
Profile dynamics describe the longitudinal or "vertical" shape of a river including its slope, depth, and elevation changes, which control how water moves, how sediment is transported, and what habitats exist along the river. Structures such as bridges, diversion dams, and grade control features can prevent a river from naturally adjusting its slope and depth, leading to erosion or sediment buildup that destabilizes the channel. Stream reaches are graded based on the number of these structures per mile, with fewer structures indicating a healthier, more naturally functioning river.
Grade | Scale | Description | Explanation |
|---|---|---|---|
A | 90-100 | Optimally functional | Low profile stressors (river has the ability to naturally adjust and has minimal to no anthropogenic impacts from in-stream grade control structures). Less than 1 grade control structures per mile. |
B | 80-89 | Highly functional | Low to moderate profile stressors (river maintains the ability to naturally adjust but is in minimally impacted anthropogenic impacts from in-stream grade control structures). 1 - 2 grade control structures per mile. |
C | 70-79 | Mostly functional | Moderate profile stressors (river's ability to naturally adjust is moderately impacted anthropogenic impacts from in-stream grade control structures). 2 - 3 grade control structures per mile. |
D | 60-69 | Party functional | Moderate to high profile stressors (river's natural ability to adjust is moderately to highly impacted by anthropogenic impacts from in-stream grade control structures). 3-4 grade control structures per mile. |
F | 50-59 | Dysfunctional | High profile stressors (river's natural ability to adjust has been highly impacted by anthropogenic impacts from in-stream grade control structures). Greater than 4 grade control structures per mile. |
N/A | N/A | Not Graded | Not Graded |