1. Stream Geomorphic Assessment of Allen Brook
Jarrett Arthur, Amy Myers
Shea Hagy, Mike McDonald

2. Allen Brook Watershed drains 12 sq. miles Flows into Winooski
after meeting
Muddy Brook

3. Characteristics of Impairment
Presence of pathogens
High concentration of suspended solids
Bank failure, erosion
Lack of adequate riparian buffer zone
Channelization leading to decrease in natural stream hydrological features such as pools and riffles

4. Methods Phase One Steps Phase Two Steps Rapid Geomorphic Rapid Habitat
Assessment Assessment
2.1
Elevation
5.2
Bridges-Culverts
2.2
Valley Length
5.3
Bank Armoring
2.3
Valley Slope
5.4
Channel Modification
2.4
Channel Slope
5.5
Dredging History
2.5
Sinuosity
6.1
Berms and Roads
2.6
Watershed Size
6.2
River Corridor Development
2.7
Channel Width
6.3
Depositional Features
2.8
Valley Width
6.4
Meander Migration
2.9
Confinement
6.5
Meander Width Ratio
2.10
Stream Type
6.6
Wavelength Ratio
3.1
Alluvial Fan
7.1
Dominant Bed Form and Material
3.2
Grade Controls
7.2
Bank Erosion/Bank Height
3.3
Geologic Materials
7.3
Ice and Debris Jam Potential
3.4
Valley Side Slopes
8.1
Impact Rating
3.5
Soil Properties
8.2
Priority Rating
4.1
Watershed Land Cover
9.1
Channel adjustment Process
4.2
Corridor Land Cover
9.2
Reach Condition
4.3
Riparian Buffers
9.3
Reach Sensitivity
4.4
Ground Water Inputs 10
Like Reach Evaluation
5.1
Flow Regulation
6.1
Epifaunal Substrate/
Available Cover
7.1
Channel Degradation (Incision)
6.2
Embeddedness
7.2
Channel Aggradation
6.3
Velocity/Depth Patterns
7.3
Channel Widening
6.4
Sediment Deposition
7.4
Change in Planform
6.5
Channel Flow Status
6.6
Channel Alteration
6.7
Frequency of Riffles/Steps
6.8
Bank Stability
6.9
Bank Vegetative Protection
6.10
Riparian Vegetative
Zone Buffer

5. Reach Designation

6. M3T3.11 Culvert Dense Sprawly Surroundings Buffer Reclaimed
Field Grass
Golden Rod
Deep Plunge Pool
Braided Channel

7. M3T3.10 Buffers Widen Braiding Ends Cobbles and Boulders
Bank Failure provides Coarse Woody Debris
Channel migration
Undercutting
Point bars
Channel Widening

8. M3T3.9 Transition Zone Degrad. and Aggrad. Present Throughout
Banks Flat and Broad
Wetland Area on Lower Portion of Right Bank
Left Bank Supports Larger Trees
Beds Still Dominated by Cobbles but Embeddedness is Occuring
Hemlock
Beech
Maple

9. M3T3.8 First Impaired Reach Area Surrounding the right bank is wetland
There is a large pond within 20 feet of the stream bank
Less Trees throughout reach
Right Buffer Gets Thinner Downstream
Old Farm Field Creeping in on Left Bank
Embeddedness Occurs Throughout
Erosion occurrs on the outside of meanders.
While they begin with beech and hemlock, the dominant trees gradually switch to willow.

10. M3T3.7 Dramatic Deterioration From Previous Reach
Buffers become nonexistent
land appears to have been cleared for farm pasture or crop
field grass is dominant species
The right bank is very wet and even has intermittent hydric soils.
Willow Grows Thinly in the Stream Channel
Streambed is Sand
Evidence of Head Cutting Exists
Incision is Dominant Force
Right Bank has Some Hydric Soils

11. M3T3.6 Final Assessed Reach
Begins and Ends at a Road Crossing with a Culvert
Surrounding Landscape is Flat
Reach is Deeply Incised
Broad Meander Migration Occurring
Streambed is Mostly Sand only Broken by Litter
Prevailing Land use is Suburban Residential Development
Prior to development, farmland predominated
The resulting ground cover is uniform field grasses.

14. Results
Figure 1. Rapid Habitat Assessment of impaired reaches compared to the attainment reaches – Allen Brook, 2004.

15. Figure 2. Rapid Geomorphic Assessment of impaired reaches as compared to attainment reaches – Allen Brook, 2004.

16. Figure 3. Rapid Habitat Assessment compared to the watershed condition on all six reaches – Allen Brook, 2004.

17. Figure 4. Rapid Geomorphic Assessment compared to the watershed condition on all six reaches – Allen Brook, 2004.

18. Figure 5. Rapid Habitat Assessment scores compared to the Rapid Geomorphic Assessment scores for all six reaches – Allen Brook, R2=.9529

19. Conclusions
Our impaired reaches are significantly more degraded than our attainment reaches both in terms of geomorphic processes and habitat suitability
The degree of impairment in all of our reaches increases in severity the further downstream the reach is located.
Current land development surrounding Allen Brook combined with the historic use of land for agricultural purposes has caused the health of the brook to decrease and the abundance of native aquatic life to suffer.
Assessment of stream condition using the ANR stream geomorphic protocols correlated to assessment using biocriteria.

20. Recommendations
The implementation of soft engineering to stabilize failing banks may be able to reduce further degradation and erosion.
The restoration of a riparian buffer of adequate width will help reduce runoff volume, velocity, increase nutrient retention, provide shading, and habitat.
Best Management Practices (BMPs) will help reduce the detrimental effects of surrounding agricultural and residential land.

21. Acknowledgements
Special thanks to Bill Gill in the library for all the help, especially at ridiculous hours of the night, and to Breck Bowden for advice and guidance throughout the whole process.