Allen Brook

ENSC 285 Final Presentation4.29.2005Keith Jennings

Allen Brook Watershed 37.5km2 3750ha Headwaters in

Williston Mouth in South

Burlington Intersects Muddy

Brook before draining into the Winooski River

Allen Brook Subwatersheds 12 Subwatersheds

for the main stem’s 12 reaches

No tribs because no other streams contribute 10% to Allen Brook

Allen Brook Land CoverReach ID

Commercial Crop Field Forest Industrial Residential Shrub Water Wetland Total

M01 1.3 14.7 17.1 34.4 1.2 26.4 0.2 3.3 1.3 100

M02 1.3 15 17 35 0.7 26.6 0.2 3.1 1.1 100

M03 1.3 15.8 17.9 36 24.5 0.2 3 1.2 100

M04 0.5 13.8 18.8 37.9 24.4 0.2 2.8 1.5 100

M05 0.1 11.1 19.5 45.4 20.1 0.2 2.1 1.7 100

M06 11.2 21.3 50.2 14 0.2 1.7 1.4 100

M07 10 19.4 53.6 13.6 0.2 1.5 1.6 100

M08 9.5 17.9 58.7 10.7 0.1 1.5 1.7 100

M09 10.6 18.5 58.6 8.3 0.1 2 1.8 100

M10 12.4 21.9 54.7 6.6 0.2 2.7 1.6 100

M11 14 32.1 44.4 4.6 0.3 2.6 2.1 100

M12 14.4 32.1 44 4.3 3.3 1.7 99.8

Allen Brook Land Cover Agriculture more common at upstream

reaches More urban and suburban cover at

downstream reaches Residential land occupies 6 times more

space in reach M01 than in M12 Forest cover is highest in the middle

reaches Total impervious cover for watershed is

only 6.4%

Allen Brook Soils

Hydrologic Water Table

Reach ID Group % Flooding % Deep % Shallow % Erodibility %

M01 B 48.5 Occasional 48.4 3 45.3 1.5 45.3 Slight 10.6

M02 Not Rated 44.4 Frequent 54.2 6 20 6 20 Moderate 43.7

M03 D 52.1 None/Rare 79.4 2 31 0 49.7 Moderate 49.1

M04 A 45.2 None/Rare 98.6 6 60.9 6 60.9 Severe 62.8

M05 C 55.7 Frequent 55.7 1.5 57.9 0 63.9 Slight 21.4

M06 C 53 None/Rare 87 2.5 53 1.5 66 Very Severe 78.4

M07 D 90.1 None/Rare 100 2 85.6 0 88.9 Very Severe 92.3

M08 D 98.9 None/Rare 100 0 98.9 -1 98.9 Slight 1.1

M09 D 92.9 None/Rare 92.9 0 79.7 -1 79.7 Slight 13.2

M10 D 53.2 None/Rare 92.4 2 53.2 0 60.8 Severe 57

M11 D 79.5 None/Rare 98.3 2 79.5 0 81.2 Slight 20.4

M12 C 71.6 None/Rare 62.5 1.5 37.5 0 51.4 Moderate 48.9

Allen Brook Soils Reaches M05 and M02 indicate frequent

water table flooding. Can be a large problem for residences in the area. Both of those reaches are about 25% residential land.

Many of the soil hydrogroups are classified as ‘D’, which is a fairly impermeable soil type. Can lead to runoff issues during large storm events.

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Scenes in Allen Brook

Conclusions

Allen Brook is impacted by suburban development pressures in its downstream reaches

Agriculture has a large impact on the brook in upstream reaches

Culverts and berms are impacting where the stream can flow

Its natural pattern is being altered

Conclusions What do we do now?

Talk to developers and landowners Development pressure in Williston will surely

increase in the future We should encourage developers to build away

from sites in the watershed that will have an effect on channel morphology and stay away from sites that experience frequent flooding

Talk to farmers in upstream reaches and encourage them to let the stream return to its natural, unstraightened path

Encourage BMP’s in Williston to mitigate stormwater effects on Allen Brook

Conclusions

Focus on higher impact reaches Reaches M07, M08, M09 and M11 have

been straightened Downstream reaches are being

encroached upon by suburban development

Look at mitigating impacts of development