Phase 1 Report - Creek Restoration Design.pdf

May 2025

MILL STREEET DAM REMOVAL –

CHITTENANGO CREEK RESTORATION

MADISON COUNTY, NEW YORK:

CONCEPTUAL DESIGN REPORT

Prepared by:

U.S. Fish and Wildlife Service

New York Field Office

3817 Luker Road

Cortland, NY 13045

P a g e | 2 May 2025

I. INTRODUCTION

The Cazenovia Area Community Development Association (CACDA) is working in partnership with the U.S. Fish and Wildlife Service (Service) to implement a comprehensive stream restoration project (Project) as part of the removal of the Mill Street Dam in the Village of

Cazenovia, Madison County, New York.

The Service will use the “Function-based Stream Restoration Project Process Guidelines” (Starr

& Harman., 2016) in developing the most appropriate design approach for the proposed project, and will conduct a reach level assessment. The stream-based assessment involves a visual assessment of stream characteristics and stability conditions upstream and downstream of the project area. The fluvial geomorphic conditions observed included channel dimensions, pattern, profile, substrate material, vertical and lateral stability, sediment supply potential, Rosgen stream type, and channel evolution. The reach level assessment will be conducted to establish the existing functional condition, determine stressors, and identify constraints at the proposed project site.

The stated goals of this stream restoration project are to create a stable stream reach following dam removal and to enhance stream habitat, reduce concentrations of sediment, detain and slow runoff, and provide stable conveyance of flows through the stream channel.

II. DESIGN DEVELOPMENT

This section presents the project constraints, design objectives, design criteria, and monitoring strategies involved in the Project.

A. CONSTRAINTS

Constraints are man-made features that limit the restoration potential of a stream restoration project. The Chenango Street Bridge (CR65) is immediately upstream of the Mill Dam and will constrain design option in its vicinity.

B. DESIGN OBJECTIVES

The goals of this stream restoration project are to enhance stream habitat, reduce concentrations of sediment (bedload and suspended), detain and slow runoff, and provide stable conveyance of flows through the stream channel. The design objectives for this project were then developed to meet these goals.

C. DESIGN DEVELOPMENT

1. Proposed Design

The major impacts to the site are due to presence of the dam resulting in some sediment accumulation upstream of the dam. There are limited opportunities to change stream planform through the reach. To meet vertical stability and sediment load reduction design goals, the

P a g e | 3 May 2025 proposed stream channel is designed to dissipate stream energy through pools, associated with constructed vane structures, to help ensure long term stability. These constructed cross vanes will also promote bedform diversity while protecting adjacent banks.

While the proper balance between plan form and in-stream structures is important for stable conditions, it is recognized that stability cannot be achieved without the proper riparian conditions. The proposed plan calls for riparian and upland plantings along the streambanks to quickly re-establish vegetation cover.

Design objectives of reducing sediment loads will be met primarily through bed stabilization.

The proposed channel work has been designed to maximize avoidance of existing native vegetation. Therefore, only minimal impacts will occur to existing vegetation and any vegetation impacted will be reused within the stream restoration project.

2. In-Stream Structures

Stream restoration projects are most vulnerable to erosive flows immediately after construction is completed. Vegetation roots need time to establish within the newly graded stream banks, and channel sub pavement and pavement layers need to form in order for long-term stability to be provided. Initial establishment of vegetation typically take 4 to 6 years in the central NY region.

During this time, in-stream structures are needed to protect against erosive flows. For the Project, in-stream structures consist of rock cross vanes and toe wood. The design riffle pool sequence will provide a stable conveyance of stream flows, maintain streambed elevations, and significantly reduce bank erosion rates.

a. Rock Cross Vane

The cross-vane will establish grade control in the proposed channel that will tie-in to the existing channel at the upstream end of the project. Cross vanes are in-stream structures used to reduce bank erosion, create a stable width/depth ratio, and maintain channel capacity, while maintaining sediment transport capacity and competence. The cross-vane is a stream habitat improvement structure that will: increase bank cover as a result of a differential raise of the water surface in the bank region; create holding and refuge cover during both high and low flow periods in the deep pool; develop feeding lanes in the flow separation zones (the interface between fast and slow water) due to the strong down welling and upwelling forces in the center of the channel;

and, create spawning habitat in the tail-out or glide portion of the pool (Rosgen, D.L., 2001).

P a g e | 4 May 2025

Figure 1Rock Cross Vane used to stabilize grade and protect banks

b. Toe Wood Structure

Toe wood structures will be used to provide lateral stability within the reach. Toe wood structures are used in certain stream types (Rosgen Bc,C & E) to reestablish stable lateral scour pools where rivers meander. The structure incorporates native woody material into a submerged undercut bank to replicate natural streambanks and add flow resistance for streambank protection

(Figure 2, Error! Reference source not found.). The majority of the wood is submerged to prevent deterioration. Incorporated into the structure is a bankfull bench to reduce bank height and improve the response of riparian vegetation (Rosgen, D.L., 2001).

3. Vegetation Design

Figure 2 Toe wood structure

P a g e | 5 May 2025

The proposed planting incorporates two zones of trees and shrubs to be planted. Riparian trees and shrubs will be planted between top of bank and five feet below the delineated top of bank.

The proposed Zone 2 plantings will provide additional vegetation stabilization above areas that will be less frequently inundated. Riparian trees and shrubs will be installed at a density of 350 stems per acre. Before permanent vegetation is planted, a temporary herbaceous seed mix will be applied in areas disturbed by grading for temporary stabilization. The application of all seeding mixtures and planting of trees and shrubs will be conducted according to the planting plan specifications would be provided in the 100% design plan set.

4. Impacts to Natural Resources

Installation of instream structures and channel modification will require in-stream work.

III. Literature Cited

Starr, R. and W. Harman. (2016). Function-based Stream Restoration Project Process Guidelines.

U.S. Fish and Wildlife Service – Chesapeake Bay Field Office. Annapolis, Maryland. CBFO-

S16-03.

Rosgen, D. (2018). The Natural Channel Design Approach to River Restoration. Unpublished course material, Wildland Hydrology, 11210 N. County Road 19, Fort Collins, CO 80524

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U.S. Fish & Wildlife Service New York Field Office

Partners for Fish and Wildlife Program

3817 Luker Road Cortland, NY 13045

Tel. (607) 753-9334

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TOE WOOD STRUCTURECROSS VANE STRUCTURE

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AutoCAD SHX Text Conceptual plan for structure placement for proposed Chittenango Creek restoration following removal of the Mill St Dam.

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