Stream Corridor Evaluation (SCORE)

Program Overview

SCORE, Stream CORridor Evaluation, is a visual stream survey program and stream impairment inventory currently being conducted by the City of Chattanooga Water Quality Program. This program was instituted to assess conditions of local watersheds and improve management and restoration decisions. SCORE provides a comprehensive and consistent approach to identify and evaluate stream channel stability, sediment loading, and in-stream habitat. This provides needed data to help both improve these stream parameters and protect public and private infrastructure. By following previously established corridor assessment protocols, Chattanooga Water Quality Program staff collect and analyze key physical, hydrologic, geologic, and biologic stream bank parameters.

The data collection, management, and analysis are specifically being used for: 1) developing an inventory of problematic stream banks, 2) identifying and prioritizing stream restoration programs, 3) proper management of activities impacting certain stream reaches, 4) establishing pre- and post-restoration water quality studies within city waters, and 5) inclusion and application in the city's watershed management and modeling programs.

Program Guidance

EPA's Clean Water Act created the National Pollutant Discharge Elimination System (NPDES). Tennessee Department of Environment and Conservation (TDEC) administers the required NPDES permits within the state of Tennessee. The SCORE program serves to satisfy Section 4.2 of the NPDES permit given to the City of Chattanooga which requires "visual stream surveys and impairment inventories." Data obtained from field activities can be used for modeling purposes. In addition, the program was designed to concurrently serve as part of the overall TMDL minimum monitoring requirements for both siltation and pathogens.

Program Elements

One of the primary benefits of the SCORE program is its ability to rapidly obtain field information and "score" it, so the data are more readily managed and understood. The metrics used for the SCORE program are as follows:

In/Near Stream Construction

-1- No construction activities within 200 ft of channel.

-3- Activities 100-200 ft from bank, but with adequate sediment BMPs.

-5- Activities <100 ft from bank with no sediment BMPs.

Channel Alteration

-1- Natural earthen channel with sediment bottom; no structures present.

-3- Current or past alteration on less than 50% of the segment.

-5- Current or past alteration on greater than 75% of the segment.

Barriers/Blockages

-1- No diversions or structures limiting stream flow or fish movement.

-3- Small or temporary structures impeding flow; noticeable channel diversion.

-5- Diversions or structures prevent flow and/or fish movement; channel diverted.

Pipes/Outfalls

-1- No outfall present or an outfall in good condition; discharge with no odor or discoloration.

-3- Outfall in poor condition; moderately damaged, could collapse/crack, or has deposit stains.

-5- Outfall in severe condition; severely damaged or shows signs of illicit discharge.

Current Erosion

-1- Banks are stable and protected by vegetation and/or roots; natural erosion patterns present.

-3- Moderate erosion is characteristic of the segment.

-5- Severe erosion is characteristic of the segment; long reaches of active erosion and/or mass wasting on any portion of the segment.

Canopy

-1- Canopy is greater than 80%.

-3- Canopy is between 40%-60%.

-5- Canopy is less than 20%.

Buffer is a function of buffer width and buffer type as determined below.

• Buffer width (left and right banks) is determined in feet as a cumulative average over the stream segment beginning from the top of the stream bank outward. Measurements are scored for the ranges of <15 ft, 15-50 ft, and >50 ft.
• Buffer type is chosen based the dominant type present for the segment. Buffer types are classified as either impervious/bare ground, turf/lawn, tall grass, shrubs, or trees.

Total Stream Corridor SCORE is the sum of all seven program metrics. The results are then classified as minor (7-12), moderate (13-23), or severe (24-35).

For further information on the SCORE Program, see the Standard Operating Procedure (SOP).

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