Coosa River Bypass HDSS Survey 2021, AL

Trutta utilized the High Definition Stream Survey (HDSS) in 2021 to evaluate a 12-mile section of the Coosa River to support Alabama Power Company’s FERC relicensing requirements for hydropower operations. We used longitudinal HDSS and cross-sectional data collection to analyze stream features. HDSS StreamView videos offered a baseline for river conditions, aiding in the easy identification of problematic areas. A comparison with Trutta’s previous surveys from 2014 and 2018 revealed positive trends, including improvements in bank condition, water depth, and channel substrate in response to initiation of environmental flows.

Contour Generation to Support Calculation of Exposed Snail Habitat: Coosa River, Alabama

For large dam operators, assessing the impacts of management actions on all of the competing uses for water can be a complex task. For the Alabama Power Company (APC), understanding the impact of a reservoir drawdown on potential habitat of endangered mussel species was one such problem. Bathymetry data was collected utilizing a sonar-based kayak-mounted depth profile system integrated with RTK-GPS to calculate surface areas exposed by reservoir drawdowns for defined contour intervals in the 6-mile Coosa River reach. Collected hydrographic data and overbank elevations from the National Elevation Dataset were imported into ArcGIS and merged into a unified geodatabase. Channel elevations were characterized in areas not represented in the survey by importing the data into HEC-RAS and interpolating missing cross-sections. The cross-sectional data was then exported into HEC-RAS and interpolated cross-sections were modeled at 10 m intervals. Interpolated cross-sections were incorporated with the survey data in an elevation geodatabase, and utilizing geospatial kriging techniques, an elevation surface was generated. This surface was utilized to generate contours for specific elevation ranges to support calculation of endangered snail habitat.

Duck River, Tennessee: A Collaboration

The Duck River is the most biologically diverse river in the United States and is also the source of drinking water for 250,000 people in Middle Tennessee. In recent years, Trutta has completed 155 miles of High Definition Stream Survey (HDSS). Completing this would have been impossible if not for the partnerships. We have partnered with a group of collaborators from various organizations (Duck River Agency, Tennessee Department of Environment and Conservation (TDEC), Columbia Power and Water Systems (CPWS), South Central Tennessee Development District (SCTDD), Tennessee State Parks, Stantec, O’Brien & Gere, and InfloDesign). These surveys collected a huge amount of valuable data to assist managers in making good decisions to achieve their goals, while keeping the Duck River healthy. Flow Modeling Our work began below Normandy Dam with TDEC. They were interested in cross-sections data for TMDL flow modeling at one-mile increments. The Cities of Lewisburg and Columbia each funded additional high-density cross-sections in their respective reservoirs for both drinking water and wastewater purposes. Drinking Water Since then, that data has been used by Columbia Power and Water to estimate current reservoir capacities for various water needs including drought planning. Engineering firms, such as O’Brien and Gere, Stantec, and InfloDesign have used the data for monitoring current drinking water intakes, as well as siting new drinking water intakes in collaboration with different municipalities and the Duck River Agency. River Corridor Data While collecting bathymetric data throughout the years, we also ran the HDSS system to collect longitudinal river corridor data. Every mile of river has StreamView video, depth data, and side scan sonar imagery that can be used for numerous different water resource management purposes. MS4 stormwater permitting, streambank restoration prioritization, and habitat suitability modeling are just some of the ways that this data could be used today. With the surveys already completed, this data can be made available to you at a reduced cost. Other Uses for HDSS Data Trutta has also been in discussions with Tennessee Wildlife Resource Agency (TWRA) to help determine habitat for endangered mussel species, with the National Resources Conservation Service (NRCS) about suitable locations for streambank plantings, and Tennessee State Parks about using the video for information and education.

Potential Infrastructure Impacts and Mitigation: Turkey Creek, Alabama

The proposed 52 mile Birmingham Northern Beltline crosses numerous creeks, and as part of minimizing the environmental impact of the project, documenting instream conditions within the affected creeks is a fundamental component. To aid in documenting the current conditions within the stream channels of Turkey Creek, our team used HDSS to provide up-to-date, geo-referenced video and develop spatially continuous maps of bank and stream conditions. The survey data can be used in many ways but this report will focus on the method’s ability to: 1) provide a baseline characterization of river bank and instream conditions in during the survey, 2) develop aquatic habitat GIS layers for depth, habitat type (pool, riffle, run), substrate type, percent embeddedness, and left and right bank condition scores, 3) document areas of high habitat suitability for endangered darter species, and 4) identify areas that are most suitable for mitigation restoration. Rather than restore streambanks where no darters will benefit from the investment, we used the HDSS data to locate areas with the greatest instream habitat combined with poor streambank condition.

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