Appendix J: Habitats Evaluation Procedure and Cost Effective Analysis

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Appendix J: Habitats

Evaluation Procedure and

Cost Effective Analysis

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LOWER OTTER TAIL RIVER ECOSYSTEM RESTORATION PROJECT

OTTER TAIL AND WILKIN COUNTIES, MINNESOTA

APPENDIX J

HABITAT EVALUATION PROCEDURE

TABLE OF CONTENTS

measures. This includes areas upstream of the Action Area that would be protected from the existing headcut that is migrating upstream. This includes the River and Wetland strata. This longitudinal boundary extends from Orwell dam to the downstream extent of the Feature Group 1 Subreach. The lateral boundary extends from the river channel and 100-meter buffer of the riparian. The Evaluation Area encompasses the overlap of the channelized and fully-restored river corridor.

Evaluation Period – The 50-year period of time into the future that benefits of proposed features are assessed. Assuming construction is completed by 2025, this period extends from 2025 to 2075.

Feature Group (FG)– A constructible unit, numbered sequentially from downstream to upstream, where a meander or series of meanders are proposed for restoration or for arresting the headcut.

There are eight Feature Groups for the proposed project labelled sequentially from downstream to upstream.

Feature Group Subreach– A segment of the river corridor associated with a FG in which habitat benefits are realized with proposed restoration. Construction of this FG is assumed to positively affect cover types within the respective subreach.

Habitat Units – The product of acres and HSI.

Land Cover – Data from the National Land Cover Database used to identify areas of major cover types: Agriculture (AG), Shrubs, Wetlands, Forest, River, and Disturbed. Precision on the

delineation of cover types was improved by comparing with aerial imagery.

Mink HSI Model (Wetland Model) – A habitat suitability index model for mink (Allen 1986) applied to wetlands/disconnected oxbows for the LOTR project.

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Modified Mink HSI Model (River Model) – A modification to the original Mink HSI model (Yager and Devendorf 2001) applicable to rivers and associated riparian for the LOTR project.

Non-Action Area - Area within the Evaluation Area where no project features are proposed, but that would be affected with restoration.

River Strata – The dominant area within the Evaluation Area where the modified mink HSI model is applied; existing or proposed river channel and land buffer extending 100 meters from the shoreline. Areas that overlap with the Wetland Strata are assigned to the River Strata.

Reference Reaches – Sites within the watershed that serve as reference sites for FWP (restored) and FWOP (degraded) conditions for the Modified Mink Model.

Suitability Index (SI) – An index on a scale of 0 (worst) to 1 (optimal) conditions assigned to a specific variable in the mink models. The overall Habitat Suitability Index (HSI) is composited across all SIs.

Target Year (TY) – Years identified throughout the 50-year evaluation period for HSI models are assessed. TYs for this evaluation are identified as 0, 1, 3, 25, and 50.

Wetland Strata - The area within the Evaluation Area where the Mink HSI model is applied;

existing or proposed wetlands and land buffer extending 100 meters from the shoreline.

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APPENDIX J

HABITAT EVALUATION PROCEDURE USED FOR THE

LOWER OTTER TAIL

AQUATIC ECOSYSTEM RESTORATION PROJECT

1. BACKGROUND

An analysis of habitat benefits was used to evaluate the potential benefits of the alternative habitat improvement features (reconnecting oxbows, and instream structures) for the proposed Lower Otter Tail River (LOTR) Ecosystem Restoration Project (project). The project is intended to address many of the habitat concerns resulting from the LOTR Channel Improvement Project constructed in the 1950s to address concerns with flooding. Active participants involved in this analysis included biologists from the St. Paul District, Corps of Engineers (Corps), the U.S. Fish and Wildlife Service (USFWS), Minnesota Department of Natural Resources (MNDNR), and Buffalo-Red River Watershed District (BRRWD).

The LOTR Channel Improvement Project was part of the comprehensive plan for the Red River of the North (Red River) drainage basin authorized by the Flood Control Acts approved June 30, 1948, and May 17, 1950. The project was constructed under one contract from 1952 to 1954, with a minor contract being completed in September 1955. The project was formally transferred to the Wilkin County Drainage and Conservancy District No. 1 in 1954 but since has been inherited by the BRRWD.

2. METHODS 2.1 Evaluation Area

The Evaluation Area used for this analysis is a 2,600-acre area that encompasses the maximum extent of the Lower Otter Tail River and associated buffer zone that would be directly affected by proposed restoration measures. The Evaluation Area is located east of the town of Breckenridge, Minnesota (Figure 1). Breckenridge is approximately 45 miles south of Fargo, North Dakota and 180 miles northwest of Minneapolis, Minnesota.

The boundaries of the Evaluation Area are Orwell Dam at the upstream extent and the

downstream extent of FG 1 at the downstream extent. The project area extends upstream of the Action Area (defined later) because of an active rapidly-moving headcut located about in the middle of the stream reach. The base plan and feature that would be included in all action alternatives is a proposed riffle structure intended to stop this headcut from moving further upstream (FG 8). The lateral boundaries are delineated based on the overlap of the existing river alignment, proposed river alignment (i.e., reconnected meanders), and a 100-meter buffer extending from the shoreline, on each side of the river channel or disconnected oxbow channel.

Existing conditions in the channelized reach are characterized by unstable banks, headcutting, excessive sediment loading, and degraded in-stream and riparian habitats caused by the 1950’s

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Channel Improvement Project. Bank failure and channel instability have resulted in excessive sediment loading, which is a significant factor in why the turbidity levels exceed the standard for aquatic life in this reach of the LOTR, the only portion of the river impaired for turbidity.

The U.S. Geological Survey (USGS) confirmed the turbidity impairments and estimated that the annual sediment load was 40,400 tons at a sampling site in Breckenridge, Minnesota (EPA 2006).

The Action Area is the areas where actual construction would occur, along an 11-mile reach of the lower portion of the river (Figure 1). Proposed ecosystem restoration would reestablish the river back to most of the oxbow segments that once were part of the natural river channel (the channelization project disconnected 27 oxbows, which are numbered sequentially from upstream to downstream). Not all oxbow segments are proposed for restoration because they were either not part of the channelization project or the benefits are anticipated to be minimal relative to cost¹. Restoration would also stabilize and improve river banks and restore stream and riparian habitat.

Restoration features in the action area have been grouped into Feature Groups (FGs) numbered sequentially as you move from downstream to upstream. Each FG has been assigned to a river subreach of the same number (Figure 2; Table 1). Each subreach is defined as the area that would be most directly affected by the respective FG and is the area that habitat benefits are quantified.

Table 1. Functional Groups and Associated Subreaches.

Feature Group

Oxbows Restored or Other Major

Features

Subreach Begin Station^a

Subreach End Station^a

Feature Begin Station^a

Feature End Station^a 1 Oxbows 26 and 27

Breckenridge

Dam 53000 48000 50400

2 Oxbows 22, 24, 25 53000 60200 55600 58000

3 Oxbows 20 and 21 60200 67700 62400 66600

4 Oxbow 18 67700 70800 68800 70400

5 Oxbows 12 - 17 70800 87200 71200 78400

6 Oxbows 8 and 9 87200 100200 96000 99200

7 Oxbows 1, 3 – 7 100200 112400 101200 107200

8 Headcut stabilization Orwell Dam 48000 107200

a Based on Houston 2019. Stations are identified by linear feet in the stationing scheme.

For the River Model, FG subreaches are further distinguished as the reaches upstream (FG 8 Subreach) and downstream (FGs 1 through 7 Subreachs) of the headcut. Under FWOP

conditions, the FG 8 Subreach would lose area directly to FG Subreach 7 as the headcut moves upstream, i.e., the FG 8 Subreach would become smaller and FG 7 Subreach would become larger. Under FWP conditions, these areas would not change as movement of the headcut would be halted.

1 Oxbow 23 appears to have cut itself off prior to the 1953 USACE project by natural processes, and is therefore not being considered for restoration. Oxbows 10, 11, and 19 are each small isolated oxbows that were excluded from analysis because, due to size, they would not provide appreciable benefits.

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2.1.1 Strata

For modeling purposes, the Evaluation Area was delineated into two strata:

River strata – existing or proposed river channel and land buffer extending 100 meters from the shoreline.

Wetland strata – existing oxbow segments (which are considered wetland type) and land buffer extending 100 meters from the shoreline².

Delineation on this basis was needed to determine which Habitat Suitability Index (HSI) model to apply (River or Wetland model) in the Habitat Evaluation Procedure (HEP) analysis,

discussed below. In addition, these areas were assessed in terms of land cover composition for input into the models. Emphasis was placed on the river strata as this is more directly linked to the proposed ecosystem restoration measures and encompasses the majority of the Evaluation Area.

2.1.2 Existing Land Cover

For analyses involving land cover, six classes are recognized: agriculture, shrubs, wetlands, forest, river (water), and disturbed.

The Evaluation Area is currently composed of 2,206 acres for the River strata and 426 acres for the Wetland strata (Figure 3; Table 2). For the River strata, the existing land class composition was, in order of dominance: agriculture (44%), forest (18%), river (17%), shrubs (16%), wetland (4%), and disturbed (2%). For the Wetland strata, the existing land class composition was: agriculture (46%), forest (33%), shrubs (10%), wetland (7%), river (3%), and disturbed (1%). The composition of land classes across the evaluation unit for both strata was: agriculture (44%), forest (20%), shrubs (15%), river (14%), wetland (4%), and disturbed (2%).

2 Areas that overlapped these two strata were assigned to the River strata, which was dominant.

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Figure 1. LOTR – Project Evaluation Area and Proposed Restoration Functional Groups.

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Figure 2. Functional Group Subreaches under Existing and Full Restoration FWP Conditions.

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Figure 3. Existing Land Cover Types for the LOTR Evaluation Area.

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Table 2. LOTR Evaluation Area – existing acreages of land cover types within each strata.

Strata TOTAL

Land Cover Types River Wetland

Acres % Acres % Acres %

AGRICULTURE 971 44 197 46 1,168 44

SHRUBS 360 16 43 10 403 15

WETLAND 77 4 31 7 108 4

FOREST 387 18 139 33 526 20

RIVER 366 17 13 3 379 14

DISTURBED 46 2 3 <1 48 <2

TOTAL: 2,206 100% 426 100% 2,6320 100%

2.2 Reference Areas

“Pristine” and “disturbed” reference areas were identified for consideration of habitat quality under Future With Project (FWP) and Future Without Project (FWOP) conditions for the River strata (Figure 4). More specifically, Habitat Suitability Index (HSI) values were calculated for these sites and used when estimating future HSIs for individual Feature Groups.

Figure 4. Reference Sites for the LOTR Project.

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2.2.1 Pristine Site

The “Pristine” reference site is a subreach of the river that was not channelized as part of the LOTR Channel Improvement Project. Conditions in this area is considered desirable and a goal throughout the Evaluation Area as part of future ecosystem restoration.

The pristine reference area is a 178-acre area within the Evaluation Area, between the headcut and Orwell Dam. This site was used for both riverine and wetland strata and is considered a relatively natural area, but is subject to the influence of Orwell Dam flow releases which is relevant to the River strata. This reference reach has been influenced to some extent by agriculture or altered hydrology from regulated releases from the dam (Figure 5). The habitat associated with the stream channel and riparian zone are believed to approach conditions in the Evaluation Area pre-channelization, and are therefore used as FWP conditions as input into the River model. The existing land class acreage was forest (69 acres), shrubs (28 acres), agriculture (32 acres), river (36 acres), and wetland (14 acres)(Error!

Reference source not found.).

Table 3. LOTR Pristine Reference Site for River Strata- Acreages of Land Cover Types.

Land Cover Types River Strata

Acres %

AGRICULTURE 32 18

SHRUBS 28 16

WETLAND 14 8

FOREST 69 39

RIVER 36 20

DISTURBED 0 0

TOTAL: 178 100%

2.2.1 Disturbed Reference Sites

Two disturbed reference sites were chosen for the river strata within the evaluation area (Figure 6Figure 6). Both sites are within channelized segments of the stream and lack of riparian cover.

Conditions in these areas are not desired in the future as part of ecosystem restoration.

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Figure 5. Pristine Reference Area for River Strata and Associated Cover Types.

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Figure 6. Disturbed Reference Areas for the River Strata.

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2.3 Target Years

Four target years (TYs) were identified throughout the 50-year planning period to capture

significant thresholds in the anticipated response (Table 4). TYs were identified primarily driven by considerations for riparian vegetation and river geomorphology.

Table 4. Identified Target Years and Rationale.

Target Year (TY)

Rationale 0 Construction begins.

1 Construction ends. Disturbance due to construction of features a factor in determining vegetation response. However, immediate response to river plan form and profile associated with grade control structures.

3 Vegetation begins to respond. Plantings for grasses and shrubs take hold.

25 Planted trees grow into mature forest.

50 End of planning period.

2.4 Alternatives

A final array of twelve alternatives was identified based on results of the Multi-Criteria Decision Assessment or MCDA (Appendix M – Plan Formulation). The estimated cost (in $2021) for action alternatives ranged from $1M (Alternative A) to $56.5 M (Alternative K)(Table 5).

Table 5. Final array of Alternatives, Associated Functional Groups, and Estimated Cost for the Proposed Project.

Alternative Functional Groups Estimated Cost

Average Annualized Cost (AAC)^a

No Action N/A $0 $0

Alt A 8 $1,023,536 $36,090

Alt B 8,3 $8,194,666 $288,944

Alt C 8,2,3 $13,770,746 $485,557

Alt D 8,3,5 $25,315,899 $892,639

Alt E 8,3,7 $19,696,436 $694,496

Alt F 8,2,3,5 $30,891,979 $1,089,251

Alt G 8,3,4,7 $24,257,626 $855,324

Alt H 8,3,5,7 $36,817,668 $1,298,191

Alt I 8,2,3,4,7 $29,833,706 $1,051,936

Alt J 8,2,3,5,7 $42,393,748 $1,494,804

Alt K 8,1,2,3,4,5,6,7 $56,518,290 $1,992,835

a Based on I&A factor of 0.03526.

2.5 HEP Methodology

The U.S. Fish and Wildlife Service’s version of Habitat Evaluation Procedures (HEP) was used to

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quantify and evaluate the potential project effects and benefits. The HEP methodology uses a Habitat Suitability Index (HSI) to rate habitat quality on a scale of 0 to 1 (1 being optimum). The HSI is multiplied by the number of acres of available habitat to obtain Habitat Units (HU’s). One HU is defined as 1 acre of optimum habitat. By comparing the projected HU’s available without a proposed action to HU’s projected to be gained with a proposed action or alternative, the benefits of different alternatives can be quantified. HUs were annualized across the 50-year planning period to estimate Average Annualized Habitat Units (AAHUs).

2.5.1 Evaluation Species and Model Selection

Restoring hydrologic, geomorphic, and habitat conditions in the project area is a high priority goal of the MNDNR and BRRWD. Habitat conditions in the LOTR area are considered suboptimal for stream fishes and riparian wildlife. The LOTR has been drastically altered, due in part to the existing flood control project that involved straightening, cleaning, and enlarging the river for drainage

improvement to local agriculture. The hydrology and instream habitats present do not provide conditions typical of other natural streams in the project area.

After a review of Corps’ approved or certified species models, two versions of the mink (Mustela vison) model were selected to quantify habitat benefits projected to result from the proposed project.

Within the evaluation area, two strata were identified corresponding to the appropriate mink model year- round (Table 6). The original mink model (Allen 1986) was applied to existing wetland oxbows and the associated 100-meter riparian buffer zone (Wetland strata). A modified version of this (modified mink model; Yager and Devendorf 2001) was applied to the river channel (existing or restored) and associated 100-meter riparian zone (River strata). Areas that overlapped the two strata were assigned to the River strata, which is dominant over the Wetland strata. This approach recognizes the habitat value of the existing oxbows that will be displaced when the river channel is constructed through these areas.

Table 6. Strata for the LOTR Evaluation Area.

STRATA DESCRIPTION APPLICABLE HEP

MODEL River Channelized river or restored river and

associated 100-meter buffer zone extending from the shoreline.

Modified Mink Model (River model)

Wetland Oxbow segments hydrologically

disconnected from the river as a result of channelization and associated 100-meter buffer zone extending from the shoreline.

Applicable to deciduous forested wetlands, evergreen scrub-shrub wetlands, deciduous scrub-shrub wetlands, and herbaceous wetlands.

Mink Model (Wetland model)

Although applicable fish models exist, the mink models were chosen because the area of

consideration extends to the associated riparian buffer zones. The mink is a common mammal species that uses river, wetland, and riparian habitats. Habitat requirements for mink include some permanent water, overhead cover for protection from avian predators, and near shore or streamside vegetation to

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provide foraging habitat for preferred food items like mice, frogs, aquatic invertebrates, and small fish.

In addition to these requirements, a relatively undisturbed stream channel is desired because of the increased food producing capabilities of natural stream channels as opposed to ditched or channelized streams. In the case of the modified mink model, habitat outputs are considered to be indicative of riverine fish and mussels, species of management interest. These models were sensitive to key habitat variables that would change between the with- and without- project conditions.

2.5.2 Model Variables

The following describes the model variables and rationale for estimating input values for the River and Wetland strata under existing, FWOP, and FWP conditions.

2.5.2.1 Percent of Year with Surface Water

This variable is found in both mink models; identified as V1 in the River model and V2 in the Wetland model. This variable is defined as the proportion of the year in which wetland and river cover types have surface water present. Optimal conditions for both models occur when surface water is present at least 75% of the year. Hydraulic modeling and professional judgment were considered for model input under existing, FWOP, and FWP conditions.

For the River model, surface water is anticipated to be present year-round (100%) under existing conditions across all Evaluation and Reference Areas, which translates into a Suitability Index (SI) of 1.0 (Table 7). Since water is released from Orwell Dam storage, the uncertainty for this Suitability Index (SI) is very low. The variable input for all conditions was assumed to be 100%.

Table 7. River Model: V1 Data and SI for the Evaluation Area and Reference Sites.

Area V1 SI

FGs 1 through 8 Subreaches 100% 1.0

Pristine Reference 100% 1.0

Degraded Reference 100% 1.0

SIs for the wetland model were based on professional judgment using location and size of wetlands.

In the Evaluation Area, disconnected oxbows located in lower subreaches (i.e., FG Subreaches 1 through 4) were assumed to have water year-round because the water surface elevations were similar to that of the river (i.e., 100%). Disconnected oxbows in the upper subreaches (FG Subreaches 5 through 8) were assumed to have water between 20 and 50% of the time to reflect the differences in water surface elevations of wetlands relative to the river. This reflects how the channel has incised over time. Compositing these across the FGs with consideration of wetland size indicated surface water is present 53% of the year (Table 8).

Table 8. Wetland Model: V1 Data and SI Estimated % of Year of Disconnected Oxbows With Surface Water Present under Existing Conditions and Associated SI.

FG Oxbow Number

% of year surface water present

SI

1 26 – 27 100%

2 22 – 25 100%

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3 20 – 21 100%

4 18 50%

5 12 – 17 40%

6 8 – 9 30%

7 1 – 7 20%

Composited across all FGs: 53% 0.55

Uncertainty is high with this variable due to variability in permeability of soils, recharge from subsurface sources, sedimentation, and other factors.

2.5.2.2 Percent Canopy Closure within 100 Meters of Water’s Edge

This is identified as V5 in the River model and V4 in the Wetland model. This is defined as the percent of ground surface that is shaded by a vertical projection of woody and herbaceous vegetation that normally remains standing after the growing season within 100 meters of the shoreline. Examples of canopy sources include trees, shrubs, and persistent herbaceous vegetation such as cattails and bulrushes. Optimal conditions for both models occurs when % canopy closure is least 75%.

Input for this variable is estimated through two steps: 1) estimating canopy closure for each cover type; and 2) compositing this across all cover types present in each strata as weighted by the

dominance of each cover type. This was done for both strata and reference sites. An example of how this was estimated is provided in Table 9 under existing conditions across the entire Evaluation Area and reference areas.

Table 9. River Model V5 and Wetland Model V4 Data: Estimated % Canopy Cover within 100 m of Waters Edge Across Strata and the Reference Areas Under Existing Conditions.

STRATA REFERENCE

River Wetland Pristine River Degraded River

COVER TYPES:

Estimated Average %

Cover^a

Total Acres

Acres covered

Total Acres

DISTURB 0% 46 0.0 3 0.0 0 0.0 11.1 0.0

AG 0% 971 0.0 197 0.0 32 0.0 76.9 0.0

SHRUBS 40% 360 144 43 17 28 11 39.1 15.6

WETLAND 10% 77 8 31 3 14 1 47.0 4.7

FOREST 90% 387 348 139 125 69 62 13.4 12.1

RIVER 0% 366 0.0 13 0.0 36 0.0 37.7 0.0

TOTAL^b: 1841 500 413 146 142 74 187.6 32.4

V5: 27% 35% 52% 17.3%

a Estimates for each cover type are based on professional judgment (B. Walther, pers. comm.).

bTotal did not include river.

For the River model, V5 for the FG 8 Subreach, FG 1 -7 Subreaches, pristine reference, and degraded reference sites were estimated to be 26%, 27%, 48%, and 17% for SIs of 0.41, 0.42, 0.67, and 0.31, respectively (Table 10).

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Area V5 SI

FG8 Subreach 26% 0.41

FGs 1 – 7 Subreaches 28% 0.44

Uncertainty with this variable is high as it has not been field verified (i.e., low accuracy). However, we do not anticipate there to be low precision.

For the Wetland model, V4 for the Evaluation Area was estimated to be 35%. The corresponding wetland SIs under existing conditions was 0.52.

2.5.2.3 Percent Cover within 1 Meter of Water’s Edge

This is identified as V6 in the River model. This is defined as the percent of ground cover that is shaded by a vertical projection within 1 meter of the shoreline. Examples include overhanging or emergent vegetation, exposed roots, debris, log jams, undercut banks, boulders, and rock crevices.

Optimal conditions occur when cover is at 100%. SIs for this variable were based on ocular assessment of aerial imagery of random sites in the evaluation area, which was applied across the entire area (Figure 7).

Segment within a Proposed Functional Group.

Composited Estimate for Existing Functional Groups: 53%

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Segment within a Pristine River Reference Site.

Composited Estimate for Pristine Reference Site: 75%

Segment within a Degraded River Reference Site.

Composited Estimate for Degraded Reference Site: 5%

Figure 7. Estimating % Cover within 1 m of Shoreline Using Aerial Imagery.

An assessment of V6 across sites in the FG 1 – 8 Subreaches, pristine reference, and degraded reference areas was 53%, 75%, and 5%, which corresponded to SIs of 0.53, 0.75, and 0.05, respectively (Table 11).

Area V5 SI

FGs 1 – 8 Subreaches 53% 0.53

Uncertainty with this variable is high as it has not been field verified (i.e., low accuracy). However, we do not anticipate there to be low precision.

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2.5.2.4 Percent Cover within the Wetland Basin

This is identified as V1 in the Wetland model. This is defined as the % of trees, shrubs, and emergent herbaceous vegetation within the wetland basin. Optimal conditions occur when this is 75% or greater. Professional judgment and ocular inspection of aerial imagery across sites were considered for model input (Figure 8).

Under existing conditions, % cover within the wetland basin across the Evaluation Area was

estimated to be 37% (Table 12Error! Reference source not found.). The corresponding SIs for the Evaluation Area under existing (and FWOP) conditions was 0.49.

Table 12. Estimated % Canopy Cover within Wetland Basin.

Total Acres 424.4 Wetland Oxbow & Buffer

COVER TYPES:

Estimated

Average % Cover^a Total Acres

Acres covered

DISTURBED 0% 3 0.0

AG 0% 197 0.0

SHRUBS 40% 43 17

WETLAND (adjusted

for EMERVEG) 30% 31 9

FOREST 90% 139 125

RIVER n/a 13

Total non-river: 413 152

V5: 36.8%

aEstimates for each cover type are based on professional judgment (B. Walther, pers. comm.).

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Figure 8. Example of Estimating % Cover within Wetland Basin.

2.5.2.5 Disturbance

This is identified as “Vstream” in the River model. This is defined as the category of disturbance along the streambank. Categories include “Highly Disturbed”, “Moderately Disturbed”, and “Not Disturbed or Natural”, with SIs of 0.4, 0.6, and 1.0, respectively. Categories were assigned on the basis of the percent of the river channel that is channelized. Under existing conditions, Vstream categories for the FG 8 Subreach, FG 1 – 7 Subreaches, Pristine and Disturbed Reference were ‘N’,

‘H’, ‘N’, and ‘H’ which corresponded to SIs of 1.0. 0.4, 1.0, and 0.4, respectively (Table 13Error!

Reference source not found.).

Table 13. River Model: Vstream Data and SI for the Evaluation Area and Reference Sites.

Area Vstream Category SI

FG 8 Subreach N 1.0

37% Cover

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FG 1 – 7 Subreaches H 0.4

Pristine Reference N 1.0

Degraded Reference H 0.4

Since this is a categorical determination based on professional judgment, the uncertainty for this variable is very low.

2.6 Existing Conditions for HSIs and HUs 2.6.1 River Model

The Habitat Suitability Index within the FG Subreaches channelized river area using the Riverine Model indicate overall HSIs for the FG 8 Subreach, FG 1 – 7 Subreaches, Pristine, and Disturbed Reference Areas of 0.60, 0.45, 0.82, and 0.18, respectively (Sub-Appendix J-1). For the FG 8 Subreach and FG 1 – 7 Subreaches, this equates to 625 and 526 Habitat Units (HUs), respectively (Table 30).

Table 14. River Model Data and HSIs for Evaluation Area and Reference Sites Under Existing Conditions.

FG 8 Subreach FG 1-7 Subreaches Pristine Reference Disturbed Reference

Acres 1046 1,160 178 225

Variable DATA HSI DATA HSI DATA HSI DATA HSI

V1 100% 1.00 100% 1.00 100% 1.00 100% 1.00

V5 26% 0.41 28% 0.44 52% 0.73 17% 0.31

V6 53% 0.53 53% 0.53 75% 0.75 5% 0.05

Vstream N 1.00 H 0.40 N 1.00 H 0.40

HSI for Cover 0.60 0.45 0.45 0.82 0.18

HSI for Water 1.00 1.00 1.00 1.00 1.00

Overall HSI 0.60 0.45 0.82 0.18

Habitat Units 625 526 145 41

2.6.2 Wetland Model

The Habitat Suitability Index of the disconnected oxbows across the Evaluation Area using the Wetland Model indicate an overall HSI of 0.28 that provide 120 HUs (Table 15).

Table 15. Wetland Model Data and HSIs for Disconnected Oxbows Under Existing Conditions.

Disconnected Oxbows

Acres 426

Variable DATA HSI

V1 37% 0.49

V2 53% 0.56

V4 35% 0.52

HSI for Food/Cover 0.28

Overall HSI 0.28

Habitat Units 120

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2.7 Compositing AAHUs

Average Annualized Habitat Units (AAHUs) were calculated using the Institute for Water Resources economic analysis program called IWR-Planning Suite II, version 2.0.9

(https://www.iwr.usace.army.mil/missions/economics/iwr-planning-suite/). This program was certified for national use in 2018. Within this program is an annualizer tool that recognized SIs for TYs with linear extrapolation. Evaluation acres were multiplied by the HSI values for each alternative and target year and averaged over the 50-year project life. Total AAHUs for each alternative were calculated by adding AAHUs from the original mink model to the AAHUs for the modified mink model. This is intended to capture losses in habitat by reverting wetland to riverine habitat. Net AAHUs for each alternative was estimated by taking the difference of the respective alternative with the No-Action alternative.

2.8 Cost Effectiveness / Incremental Cost Analysis

An evaluation of cost effectiveness and incremental cost analysis was completed using the Institute for Water Resources economic analysis program called IWR-Planning Suite II. The environmental outputs used for estimating project benefits are the net gains in AAHUs. Construction costs in 2021 US dollars for the various project features were provided by the Cost Engineering Section of the St.

Paul District, Corps of Engineers. The construction costs were annualized across the planning period to estimate Average Annualized Costs (AAC).

2.9 Data Requirements

Geographic information (land use, vegetation, topography, aerial imagery) is available concerning past and recent existing conditions in the LOTR area. An on-site inspection and “windshield”

survey of the area provided additional information. Some in-field measurement of habitat variables was completed in the spring of 2018 and used to estimate data for variable inputs for HSI calculations.

However, this was conducted during high flows; additional data collection during base flows is recommended.

Some hydraulic modeling was done to identify existing flow conditions in the project area and to develop design criteria for meeting the project goals. A discussion of this modeling effort is presented in the Hydraulics Appendix. This information was used when considering the level of connectivity to, and response of, riparian vegetation.

In many cases, data needed for model input was not readily available. In these cases, professional judgment of subject matter experts from the Corps, MNDNR, USFWS, and BRWD was used.

All information was used for providing model inputs for existing conditions. Trend analysis and a nearby reference site provided an indication of probable future conditions and a basis for identifying potential project responses.

Software used in this analysis included ArcGIS and Excel.

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2.10 Assumptions

General assumptions used in completing the evaluation include the following:

1. HSIs:

a) HSIs for existing conditions in the Degraded Reference areas are representative of FWOP conditions for unrestored FGs 1 through FG 5 Subreaches for TYs 25 through 50. There is a gradual linear decline in vegetation response that bottoms out at TY 25.

b) HSIs for existing conditions in the Degraded Reference areas are representative of FWOP conditions for unrestored FGs 6 and FG 7 Subreaches for TY 50. There is a gradual linear decline in vegetation response between TYs 0 through 50. This is to account for the proximity of these FGs in relation to the headcut.

c) HSIs for existing conditions in the Pristine Reference areas are representative of FWP conditions for restored FG 1 through FG 7 Subreaches for TYs 3 through 50.

Though there is an immediate response with re-directing the river through high density vegetated cover types oxbows, disturbance associated with construction will exist.

d) HSIs for the FG 8 Subreach will be maintained under FWOP and most FWP conditions. However, synergistic effects will be realized if all proposed features are built, resulting in HSIs similar to the Pristine Reference Reach that is realized for TYs 3 through 50. (See Figure 9 for example).

Figure 9. River Model HSIs Across Target Years.

2) Linear response for cover types between TYs.

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

0 10 20 30 40 50

HS I

Target Years

River Model HSIs

FG8 Subreach FGs Restored

FGs 1 - 5 Not Restored FGs 6 - 7 Not Restored

(28)

3) Based on professional judgment, estimating % cover by cover type (Wetland V4 or River V5), the following values were used:

Cover Type % cover

Disturbed 0

AG 0

SHRUBS 40

WETLAND 10

FOREST 90

4) Based on professional judgment, estimating % cover by cover type (Wetland V1), the following values were used:

Cover Type % cover

Disturbed 0

AG 0

SHRUBS 40

WETLAND 30

FOREST 90

5) Percent cover (V4 or V5) was composited across cover types to provide a single value for the strata.

6) The period of analysis for this project is 50 years.

3. RESULTS

Model matrices and Habitat Suitability Index (HSI) calculations for the River Strata and Wetland Strata are presented in Sub Appendices A and B, respectively. HSIs were calculated for the existing conditions, for projected FWOP conditions, and for the various combinations of riparian corridor restoration and wetland restoration.

3.1 River Strata (Modified Mink HSI Model)

Results for the River Strata using the modified mink model for alternatives are shown in Table 16 through Table 27.

3.1.1 No Action

Under FWOP conditions, the FG 8 Subreach would go from 1,046 acres to 382 acres that would provide 430 AAHUs throughout the Evaluation Period. The FG 1 – 5 Subreaches would remain stable at 719 acres that would provide 180 AAHUs. The FG 6 – 7 Subreaches would go from 441 to 1,105 acres that would provide 225 AAHUs. The total for the FWOP condition would be 835 AAHUs (Table 16).

Table 16. River Model FWOP Condition: HSIs and HUs Throughout the Evaluation Period.

FG 8 Subreach

(29)

TY 0 1 3 25 50

Acres 1046.1 1032.8 1006.3 714.2 382.3

HSI 0.60 0.60 0.60 0.60 0.60

HUs 629.3 621.3 605.3 429.7 230.0

Accrued HUs 625.3 1226.7 11384.9 8245.8

AAHUs 429.7

FG 1 - 5 Subreaches 0 1 3 25 50

Acres 719.0 719.0 719.0 719.0 7198.0

HSI 0.45 0.44 0.42 0.18 0.18

HUs 325.9 318.1 302.6 131.7 131.7

Accrued HUs 322.0 620.7 4777.5 3293.1

AAHUs 180.3

FG 6 & 7 Subreaches 0 1 3 25 50

Acres 441.2 454.45 481.0 773.1 1104.9

HSI 0.45 0.45 0.44 0.32 0.18

HUs 200.0 203.5 210.2 246.0 202.4

Accrued HUs 201.8 413.8 5018.6 5605.5

AAHUs 224.8

TOTAL AAHUs 834.7

3.1.2 Alternative A (Base Plan)

Under Alternative A, the FG 8 Subreach area would be remain stable at 1,046 acres to provide 629 AAHUs throughout the Evaluation Period. The 719 acres in the unrestored FG 1 – 5 Subreaches would provide 180 AAHUs. The 441 acres in the unrestored FG 6 – 7 Subreaches would provide 140 AAHUs. Though there would be no gain in acreage for the River Strata, the enhanced quality of habitat associated with this alternative would provide a total of 950 AAHUs for a net gain of 115 AAHUs (Table 17).

Table 17. River Model Alternative A: HSIs and HUs Throughout the Evaluation Period.

FG 8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

HSI 0.60 0.60 0.60 0.60 0.60

HUs 629.3 629.3 629.3 629.3 629.3

Accrued HUs 629.3 1258.6 13844.6 15732.5

AAHUs 629.30

(30)

FG 1 - 5 Subreaches 0 1 3 25 50

Acres 719.0 719.0 719.0 719.0 719.0

HSI 0.45 0.44 0.42 0.18 0.18

Hus 325.9 318.1 302.60 131.7 131.7

Accrued Hus 322.0 620.7 4777.5 3293.1

AAHUs 180.3

FG 6 & 7 Subreaches 0 1 3 25 50

Acres 441.2 441.2 441.2 441.2 441.2

HSI 0.45 0.45 0.44 0.32 0.18

Hus 200.0 197.6 192.8 140.4 80.8

Accrued Hus 198.8 390.4 3665.4 2765.3

AAHUs 140.4

TOTAL AAHUs 950.0

3.1.3 Alternative B

In comparison to the Base Plan, Alternative B would have no changes to the FG 8 and the FG 6-7 Subreaches. Restoration of the 185-acre FG 3 would result in a gain of 29 acres that provide 149 AAHUs. The 585 acres in the unrestored FG 1, 2, 4, and 5 Subreaches would provide 147 AAHUs.

The increased acreage and enhanced quality of habitat associated with this alternative would provide 1,065 AAHUs for a net gain of 231 AAHUs over the No Action (Table 18).

Table 18. River Model Alternative B: HSIs and HUs Throughout the Evaluation Period.

FG8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

FG 8 Subreach HSI 0.60 0.60 0.60 0.60 0.60

Hus 629.3 629.3 629.3 629.3 629.3

Accrued Hus 629.3 1258.6 13844.6 15732.5

AAHUs 629.3

FG 3 Subreach 0 1 3 25 50

Acres 134.3 185.2 185.2 185.2 185.2

HSI 0.45 0.57 0.82 0.82 0.82

Hus 60.9 106.4 151.3 151.3 151.3

Accrued Hus 83.7 257.8 3329.4 3783.4

AAHUs 149.1

FG 1, 2, 4, 5 Subreaches 0 1 3 25 50

(31)

Acres 584.7 584.7 584.7 584.7 584.7

HSI 0.45 0.44 0.42 0.18 0.18

Hus 265.0 258.7 246.1 107.1 107.1

Accrued Hus 261.8 504.7 3884.9 2677.8

AAHUs 146.6

FG 6 & 7 Subreaches 0 1 3 25 50

Acres 441.2 441.2 441.2 441.2 441.2

HSI 0.45 0.45 0.44 0.32 0.18

Hus 200.0 197.6 192.8 140.4 80.8

Accrued Hus 198.8 390.4 3665.4 2765.3

AAHUs 140.4

TOTAL AAHUs 1065.4

3.1.4 Alternative C

In comparison to the Base Plan, Alternative C would have no changes to the FG 8 and the FG 6-7 Subreaches. Restoration in the FG 2 and FG 3 would result in a gain of 91 acres that provide 149 AAHUs. The 585 acres in the unrestored FG 1,2,4, and 5 Subreaches would provide 284 AAHUs.

The increased acreage and enhanced quality of habitat associated with this alternative would provide 1,168 AAHUs for a net gain of 334 AAHUs over the No Action (Table 19).

Table 19. River Model Alternative C: HSIs and HUs Throughout the Evaluation Period.

FG8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

HSI 0.60 0.60 0.60 0.60 0.60

Hus 629.3 629.3 629.3 629.3 629.3

Accrued Hus 629.3 1258.6 13844.6 15732.5

AAHUs 629.3

FG 2 & 3 Subreaches 0 1 3 25 50

Acres 262.4 352.9 352.9 352.9 352.9

HSI 0.45 0.57 0.82 0.82 0.82

Hus 118.9 202.8 288.3 288.3 288.3

Accrued Hus 160.8 491.1 6343.2 7208.2

AAHUs 284.1

FG 1, 4, 5 Subreaches 0 1 3 25 50

Acres 456.6 456.6 456.6 456.6 456.6

(32)

HSI 0.45 0.44 0.42 0.18 0.18

Hus 207.0 202.0 192.2 83.7 83.7

Accrued Hus 204.5 394.2 3034.1 2091.4

AAHUs 114.5

FG 6 & 7 Subreaches 0 1 3 25 50

Acres 441.2 441.2 441.2 441.2 441.2

HSI 0.45 0.45 0.44 0.32 0.18

Hus 200.0 197.6 192.8 140.4 80.8

Accrued Hus 198.8 390.4 3665.4 2765.3

AAHUs 140.4

TOTAL AAHUs 1168.2

3.1.5 Alternative D

In comparison to the Base Plan, Alternative D would have no changes to the FG 8 and the FG 6-7 Subreaches. Restoration in the FG 3 and FG 5 would result in a gain of 176 acres that provide 482 AAHUs. The 297 acres in the unrestored FG 1, 2, and 4 Subreaches would provide 74 AAHUs. The increased acreage and enhanced quality of habitat associated with this alternative would provide a total of 1,326 AAHUs for a net gain of 491 AAHUs over the No Action (Table 20).

Table 20. River Model Alternative D: HSIs and HUs Throughout the Evaluation Period.

FG8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

HSI 0.60 0.60 0.60 0.60 0.60

Hus 629.3 629.3 629.3 629.3 629.3

Accrued Hus 629.3 1258.6 13844.6 15732.5

AAHUs 629.3

FG 3 & 5 Subreaches 0 1 3 25 50

Acres 422.3 598.4 598.4 598.4 598.4

HSI 0.45 0.57 0.82 0.82 0.82

Hus 191.4 343.8 488.9 488.9 488.9

Accrued Hus 267.6 832.7 10755.4 12222.0

AAHUs 481.6

FG 1, 2, 4 Subreaches 0 1 3 25 50

Acres 296.7 296.7 296.7 296.7 296.7

HSI 0.45 0.44 0.42 0.18 0.18

(33)

Hus 134.5 131.3 124.9 54.4 54.4

Accrued Hus 132.9 256.1 1971.5 1358.9

AAHUs 74.4

FG 6 & 7 Subreaches 0 1 3 25 50

Acres 441.2 441.2 441.2 441.2 441.2

HSI 0.45 0.45 0.44 0.32 0.18

Hus 200.0 197.6 192.8 140.4 80.8

Accrued Hus 198.8 390.4 3665.4 2765.3

AAHUs 140.4

TOTAL AAHUs 1325.6

3.1.6 Alternative E

In comparison to the Base Plan, Alternative E would have no changes to the FG 8 Subreach.

Restoration in the FG 3 and FG 7 Subreaches would result in a gain of 151 acres that provide 408 AAHUs. The 585 acres in the unrestored FG 1, 2, 4, and 5 Subreaches would provide 147 AAHUs.

The 220 acres in the unrestored FG 6 Subreaches would provide 70 AAHUs. The increased acreage and enhanced quality of habitat associated with this alternative would provide a total of 1,254 AAHUs for a net gain of 419 AAHUs over the No Action (Table 21).

Table 21. River Model Alternative E: HSIs and HUs Throughout the Evaluation Period.

FG8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

HSI 0.60 0.60 0.60 0.60 0.60

Hus 629.3 629.3 629.3 629.3 629.3

Accrued Hus 629.3 1258.6 13844.6 15732.5

AAHUs 629.3

FG 3 & 7 Subreaches 0 1 3 25 50

Acres 355.7 506.8 506.8 506.8 506.8

HSI 0.45 0.57 0.82 0.82 0.82

Hus 161.2 291.2 414.1 414.1 414.1

Accrued Hus 226.2 705.3 9109.7 10352.0

AAHUs 407.9

FG 1, 2, 4, 5 Subreaches 0 1 3 25 50

Acres 584.7 584.7 584.7 584.7 584.7

HSI 0.45 0.44 0.42 0.18 0.18

(34)

Hus 265.0 258.7 246.1 107.1 107.1

Accrued Hus 261.9 504.8 3884.9 2677.8

AAHUs 146.6

FG 6 Subreaches 0 1 3 25 50

Acres 219.8 219.8 219.8 219.8 219.8

HSI 0.45 0.45 0.44 0.32 0.18

Hus 99.6 98.4 96.1 69.9 40.3

Accrued Hus 99.0 194.5 1826.1 1377.7

AAHUs 69.94

TOTAL AAHUs 1253.69

Net AAHUs 419.0

3.1.7 Alternative F

In comparison to the Base Plan, Alternative F would have no changes to the FG 8 and the FG 6 - 7 Subreaches. Restoration in the FG 2, FG 3 and FG 5 Subreaches would result in a gain of 216 acres that provide 617 AAHUs. The 169 acres in the unrestored FG 1 FG 4 Subreaches would provide 42 AAHUs. The increased acreage and enhanced quality of habitat associated with this alternative would provide a total of 1,429 AAHUs for a net gain of 594 AAHUs over the No Action (Table 22).

Table 22. River Model Alternative F: HSIs and HUs Throughout the Evaluation Period.

FG8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

HSI 0.60 0.60 0.60 0.60 0.60

Hus 629.3 629.3 629.3 629.3 629.3

Accrued Hus 629.3 1258.6 13844.6 15732.5

AAHUs 629.3

FG 2, 3, 5 Subreaches 0 1 3 25 50

Acres 550.3 766.1 766.1 766.1 766.1

HSI 0.45 0.57 0.82 0.82 0.82

Hus 249.4 440.1 625.9 625.9 625.9

Accrued Hus 344.8 1066.0 13769.2 15646.8

AAHUs 616.5

FG 1, 4 Subreaches 0 1 3 25 50

Acres 168.7 168.7 168.7 168.7 168.7

HSI 0.45 0.44 0.42 0.18 0.18

(35)

Hus 76.4 74.6 71.0 30.9 30.9

Accrued Hus 75.5 145.6 1120.7 772.5

AAHUs 42.3

FG 6, 7 Subreaches 0 1 3 25 50

Acres 441.2 441.2 441.2 441.2 441.2

HSI 0.45 0.45 0.44 0.32 0.18

Hus 200.0 197.6 192.8 140.4 80.8

Accrued Hus 198.8 390.4 3665.4 2765.3

AAHUs 140.4

TOTAL AAHUs 1428.5

Net AAHUs 593.8

3.1.8 Alternative G

In comparison to the Base Plan, Alternative G would have no changes to the FG 8 Subreach.

Restoration in the FG 3, FG 4 and FG 7 Subreaches would result in a gain of 170 acres that provide 457 AAHUs. The 543 acres in the unrestored FG 1, FG2, and FG 5 Subreaches would provide 136 AAHUs. The 220 acres in the unrestored FG 6 Subreaches would provide 70 AAHUs. The increased acreage and enhanced quality of habitat associated with this alternative would provide a total of 1,292 AAHUs for a net gain of 457 AAHUs over the No Action (Table 23).

Table 23. River Model Alternative G: HSIs and HUs Throughout the Evaluation Period.

FG8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

HSI 0.60 0.60 0.60 0.60 0.60

Hus 629.3 629.3 629.3 629.3 629.3

Accrued Hus 629.3 1258.6 13844.6 15732.5

AAHUs 629.3

FG 3, 4, 7 Subreaches 0 1 3 25 50

Acres 397.5 567.4 567.4 567.4 567.4

HSI 0.45 0.57 0.82 0.82 0.82

Hus 180.2 326.0 463.5 463.5 463.5

Accrued Hus 253.1 789.5 10198.0 11588.7

AAHUs 456.6

FG 1, 2, 5 Subreaches 0 1 3 25 50

Acres 542.9 542.9 542.9 542.9 542.9

(36)

HSI 0.45 0.44 0.42 0.18 0.18

Hus 246.1 240.2 228.5 99.5 99.5

Accrued Hus 243.1 468.7 3607.3 2486.5

AAHUs 136.1

FG 6 Subreaches 0 1 3 25 50

Acres 219.8 219.8 219.8 219.8 219.8

HSI 0.45 0.45 0.44 0.32 0.18

Hus 99.6 98.4 96.1 69.9 40.3

Accrued Hus 99.0 194.5 1826.1 1377.6

AAHUs 69.9

TOTAL AAHUs 1291.9

Net AAHUs 457.2

3.1.9 Alternative H

In comparison to the Base Plan, Alternative H would have no changes to the FG 8 Subreach.

Restoration in the FG 3, FG 5 and FG 7 Subreaches would result in a gain of 276 acres that provide 740 AAHUs. The 297 acres in the unrestored FG 1, FG2, and FG 4 Subreaches would provide 74 AAHUs. The 220 acres in the unrestored FG 6 Subreaches would provide 70 AAHUs. The increased acreage and enhanced quality of habitat associated with this alternative would provide a total of 1,514 AAHUs for a net gain of 679 AAHUs over the No Action (Table 24).

Table 24. River Model Alternative H: HSIs and HUs Throughout the Evaluation Period.

FG8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

HSI 0.60 0.60 0.60 0.60 0.60

Hus 629.3 629.3 629.3 629.3 629.3

Accrued Hus 629.3 1258.6 13844.6 15732.5

AAHUs 629.3

FG 3, 5, 7 Subreaches 0 1 3 25 50

Acres 643.7 920.0 920.0 920.0 920.0

HSI 0.45 0.57 0.82 0.82 0.82

Hus 291.8 528.5 751.6 751.6 751.6

Accrued Hus 410.1 1280.2 16535.7 18790.6

AAHUs 740.3

FG 1, 2, 4 Subreaches 0 1 3 25 50

(37)

Acres 296.7 296.7 296.7 296.7 296.7

HSI 0.45 0.44 0.42 0.18 0.18

Hus 134.5 131.3 124.9 54.4 54.4

Accrued Hus 132.9 256.1 1971.5 1358.9

AAHUs 74.4

FG 6 Subreaches 0 1 3 25 50

Acres 219.8 219.8 219.8 219.8 219.8

HSI 0.45 0.45 0.44 0.32 0.18

Hus 99.6 98.4 96.1 69.9 40.3

Accrued Hus 99.0 194.5 1826.1 1377.6

AAHUs 69.9

TOTAL AAHUs 1514.0

Net AAHUs 679.3

3.1.10 Alternative I

In comparison to the Base Plan, Alternative I would have no changes to the FG 8 Subreach.

Restoration in the FG 2, FG 3, FG 4 and FG 7 Subreaches would result in a gain of 210 acres that provide 592 AAHUs. The 415 acres in the unrestored FG 1 and FG 5 Subreaches would provide 104 AAHUs. The 220 acres in the unrestored FG 6 Subreaches would provide 70 AAHUs. The increased acreage and enhanced quality of habitat associated with this alternative would provide a total of 1,395 AAHUs for a net gain of 560 AAHUs over the No Action (Table 25).

Table 25. River Model Alternative I: HSIs and HUs Throughout the Evaluation Period.

FG8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

HSI 0.60 0.60 0.60 0.60 0.60

Hus 629.3 629.3 629.3 629.3 629.3

Accrued Hus 629.3 1258.6 13844.6 15732.5

AAHUs 629.3

FG 2, 3, 4, 7 Subreaches 0 1 3 25 50

Acres 525.5 735.1 735.1 735.1 735.1

HSI 0.45 0.57 0.82 0.82 0.82

Hus 238.2 422.3 600.5 600.5 600.5

Accrued Hus 330.3 1022.8 13211.8 15013.5

AAHUs 591.6

(38)

FG 1, 5 Subreaches 0 1 3 25 50

Acres 414.9 414.9 414.9 414.9 414.9

HSI 0.45 0.44 0.42 0.18 0.18

Hus 188.0 183.6 174.6 76.0 76.0

Accrued Hus 185.8 358.1 2756.5 1900.1

AAHUs 104.0

FG 6 Subreaches 0 1 3 25 50

Acres 219.8 219.8 219.8 219.8 219.8

HSI 0.45 0.45 0.44 0.32 0.18

Hus 99.6 98.4 96.1 69.9 40.3

Accrued Hus 99.0 194.5 1826.1 1377.6

AAHUs 69.9

TOTAL AAHUs 1394.8

Net AAHUs 560.1

3.1.11 Alternative J

In comparison to the Base Plan, Alternative J would have no changes to the FG 8 Subreach.

Restoration in the FG 2, FG 3, FG 5 and FG 7 Subreaches would result in a gain of 316 acres that provide 875 AAHUs. The 169 acres in the unrestored FG 1 and FG 4 Subreaches would provide 42 AAHUs. The 220 acres in the unrestored FG 6 Subreaches would provide 70 AAHUs. The increased acreage and enhanced quality of habitat associated with this alternative would provide a total of 1,617 AAHUs for a net gain of 782 AAHUs over the No Action (Table 26).

Table 26. River Model Alternative J: HSIs and HUs Throughout the Evaluation Period.

FG8 Subreach

TY 0 1 3 25 50

Acres 1046.1 1046.1 1046.1 1046.1 1046.1

HSI 0.60 0.60 0.60 0.60 0.60

Hus 629.3 629.3 629.3 629.3 629.3

Accrued Hus 629.3 1258.6 13844.6 15732.5

AAHUs 629.3

FG 2, 3, 5, 7 Subreaches 0 1 3 25 50

Acres 771.7 1087.7 1087.7 1087.7 1087.7

HSI 0.45 0.57 0.82 0.82 0.82

Hus 349.8 624.9 888.6 888.6 888.6

Accrued Hus 487.3 1513.5 19549.5 22215.3

AAHUs 875.3

Appendix J: Habitats Evaluation Procedure and Cost Effective Analysis