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Buffalo River and Long Branch Sediment TMDLs. Upper Buffalo River. Middle Buffalo River. Public Meeting Gene Yagow April 25, 2013. Long Branch. Lower Buffalo River. Overview. Impairment Stressor Analysis → Sediment Watershed characterization GWLF sediment modeling

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Buffalo River and Long Branch Sediment TMDLs

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Buffalo River and Long Branch Sediment TMDLs

Upper

Buffalo

River

Middle

Buffalo

River

Public Meeting

Gene Yagow

April 25, 2013

Long Branch

Lower

Buffalo

River


Overview

  • Impairment

  • Stressor Analysis → Sediment

  • Watershed characterization

  • GWLF sediment modeling

  • Reference Watershed Approach

  • TMDL components

  • Allocation Scenarios


Water Quality Impairment


Biological Monitoring and Rating

Healthy

Impaired

VSCI = Virginia Stream Condition Index


Biological Monitoring and Rating

Healthy

Impaired

VSCI = Virginia Stream Condition Index


Stressor Analysis


Stressor Analysis → Sediment

  • Long Branch

    • Poor habitat metric scores for: “Sediment Deposition”

    • > 50% mean Embeddedness

    • LRBS = 0.28 (LRBS > -0.5 indicates normal sediment load)

  • Buffalo River

    • Poor habitat metric scores for: “Riparian Buffer Zone Width”

    • > 50% mean Embeddedness

    • LRBS = - 0.32


Watershed characterization


Watershed characterization

Watershed segmentation

Land use

Soils

Slope

“Future Growth”

Existing BMPs


Watershed segmentation


Land Use Distribution


Future Growth

  • Simulation of a “future” land use condition

    • Assume growth is minimal in the watershed

    • Allocated construction permit area as 2% of developed land uses


BMP representation

  • DCR data downloaded by 6th order watershed for those BMPs relevant to sediment removal

  • None in the reference watershed, but several throughout the Long Branch and Buffalo River watersheds

  • BMPs are land use-specific

  • BMPs were credited as:

    • A land use change, or as

    • An efficiency applied to the applicable land use or to the upland area benefitted


The Reference Watershed Approach


TMDL Target Load

Reducing load in the impaired watershed to the target TMDL load is expected to restore the benthic community

Example Reference Watershed TMDL

Impaired

Load

Non-impaired

ImpairedWatershed

TMDL Reference Watershed


Impaired and Comparison Watersheds

Healthy VSCI Score

Land use distribution

Size

Slope

Elevation

Physiographic region

River basin

Soil erodibility

Beaver

Creek

Harris

Creek

Reed

Creek

Wreck

Island

Creek

Fishpond

Creek

SF Falling

River


Reference Watershed Selection

  • Fishpond Creek

    • Most similar land use distribution

    • Smallest drainage area


Reference Watershed Selection

  • Fishpond Creek

    • Most similar land use distribution

    • Similar elevation


HYSadj

4,252 ha

Reference Watershed Area-adjustment Example

HYS

20,789 ha

TMB

4,252 ha


GWLF Sediment Modeling


GWLF Sediment Loads

Cropland

Pasture

Categories

Developed

Land uses

LDI = low intensity developed; MDI = medium intensity developed; HDI = high intensity developed

TMDL


GWLF Sediment Loads

Cropland

Pasture

Categories

Developed

Land uses

LDI = low intensity developed; MDI = medium intensity developed; HDI = high intensity developed

TMDL


TMDL Components


Permitted Sediment Loads (WLA)

Industrial Stormwater General Permits

*Average annual runoff simulated for the HDI land use category.

Construction Permits

*Average annual load simulated for the Barren land use category.


Long Branch Sediment TMDL Components

  • TMDL = WLA + LA + MOS

    • TMDL = area-adjusted load from reference watershed

    • WLA = permitted loads

    • MOS = margin of safety (10%)

    • LA = remaining load allocated for non-point sources


Buffalo River Sediment TMDL Components

  • TMDL = WLA + LA + MOS

    • TMDL = area-adjusted load from reference watershed

    • WLA = permitted loads

    • MOS = margin of safety (10%)

    • LA = remaining load allocated for non-point sources


Allocation Scenarios


Allocation Scenarios – Long Branch

  • Sediment load reductions are required

    • from “Future” Conditions in Long Branch

    • To the target allocation load

Target Allocation Load = TMDL - MOS

= 456.5 – 45.6 = 410.9 tons/yr


Allocation Scenarios – Buffalo River

  • Sediment load reductions are required

    • from “Future” Conditions in Buffalo River

    • To the target allocation load

Target Allocation Load = TMDL - MOS

= 4,414.8 – 441.5 = 3,973.3 tons/yr


Potential Sediment Reduction Targets

Pastures with stream access

Pastures with fair or poor conditions

Eroding field roads

Localized disturbed areas


Next Steps

  • Report will be available April 30, 2013

  • Public comment open until June 13, 2013

  • Finalize report and submit to EPA

  • Begin implementation planning


Contact Information

Gene Yagow Biological Systems Engr. Dept.

306 Seitz Hall (0303)Virginia TechBlacksburg, VA 24061

eyagow@vt.edu540-231-2538


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