Mid-Chesapeake Bay Feasibility Study

Mid-Chesapeake Bay Feasibility Study

• Tier I: Island needs to be in study area• Tier II:

– Island needs to be or have historically been at least 200 acres; currently needs to possess the ability to be 200 acres or more

– Island must be reasonably accessible for dredged material placement

– Island restoration cannot negatively affect the hydraulic conditions of existing river systems

– Island cannot significantly impact current navigation of existing waterways

– Must be an island/not shoreline

Screening Criteria

• Tier II Continued: – Island must not be a highly populated center– Island must not involve any unexploded ordinance

or hazardous, toxic and radioactive waste– If island is currently State or Federally managed as

a wildlife area, must have support from the landowners for restoration

– Compatibility with any other Corps-led studies being conducted on the island

Barren Island, Dorchester County Holland Island, Dorchester County Hoopers Islands, Dorchester County James Island, Dorchester County Little Deal Island, Somerset County Ragged Island, Dorchester County Smith Island, Somerset County South Marsh Island, Somerset County

• Screen the Island(s)

• Collect Detailed Environmental - Engineering - Socioeconomic Data

• Prepare Conceptual Plans– Determine Potential Island

Configurations/Acreages• No configuration pre-determined

• Analyze/Compare Plans

• Select Recommended Plan

Formulate Alternative Plans

Corps Six Step Planning Process

• Specify Problems and Opportunities

• Inventory and Forecast Conditions

• Formulate Alternative Plans

• Evaluate Effects of Alternative Plans

• Compare Alternative Plans

• Select Recommended Plan

Site Locations:James and

Barren Islands Dorchester

County, MDJamesIsland

BarrenIsland

James Island Project Concept Area

James Island Study FindingsCOASTAL ENGINEERING

• Water depths in concept area(s) are 2-12 feet

• Highest waves approach from north and south

• East side of island sheltered from waves

• Longest fetch from south

• Currents relatively weak• Maximum velocity 1 ft/sec

• Update bathymetric survey Fall 2002

James Island Study FindingsHYDRODYNAMICS & SEDIMENTATION

• Minimal impacts on local tidal elevations• Current velocities impacted

– Maximum change ±0.4 ft/sec

• Beneficial effects on sedimentation rates and patterns– Less shoreline erosion of James Island and portions of

Taylors Island

• Probable reduction of suspended sediment and improved water quality

James Island Study FindingsEXISTING ENVIRONMENTAL CONDITIONS

Fall 2001/2002 & Summer 2002 Studies

• In situ water quality results were in expected range

• Diverse fish community with juveniles of commercially important species

• Essential Fish Habitat for 9 finfish species– Bluefish, red drum and summer flounder present

• Low B-IBI scores – Average score of 1.6 in Summer 2002

Habitat Types on

James Island

James Island Study FindingsENVIRONMENTAL CONDITIONS (continued)

• Variety of wildlife utilizes island remnants– 42 bird species present– 9 species of wildlife

• No adverse impacts expected on terrestrial vegetation, including wetlands

• Commercial crabbing within concept area will be displaced

• Temporary viewshed and noise disturbance during construction

• No cultural resources within concept area

Current Erosion at James Island

James Island Additional Studies

• Crab Pot Surveys– April – September

• Submerged Aquatic Vegetation (SAV) Survey & Popnetting– Late season grasses

• Pound net surveys• Clam Surveys

– Soft shell– Razor shell

Barren Island

ConceptArea

Habitat Types on Barren Island

Barren Island Study FindingsCOASTAL ENGINEERING

• Water depths in concept area are 3-10 feet• Highest wind speeds from the southwest and

northwest• Longest fetch from the south

• Eastern side of island requires less armor because it is sheltered

Barren Island Study FindingsENVIRONMENTAL CONDITIONS

Fall 2002 & Summer 2002 Studies

• In situ water quality results were in expected range• Area inhabited by numerous finfish species

– Several species support commercial and recreational fisheries

• Essential Fish Habitat for 9 finfish species– Bluefish, summer flounder, and red drum present in area

• B-IBI scores were high– Average 3.84

• SAV beds present along eastern shoreline and in quiescent waters east of island

• RTE species: bald eagle, royal tern, Wilson’s plover

Barren Island Study FindingsENVIRONMENTAL CONDITIONS (continued)

• Two NOBs located in areas adjacent to proposed dike alignment

• Island important habitat for colonial waterbirds and wading birds– 61 bird species observed in Summer 2002

• Variety of wildlife utilizes island remnants– 13 species

• Reduction of commercial crabbing area• Negligible noise and viewshed disturbance• MHT- no records of historically significant sites

Erosion at Barren Island

Barren Island Additional Studies

• Crab Pot Surveys– May – September

• Submerged Aquatic Vegetation (SAV) Survey & Popnetting– Late season grasses

• Pound net surveys• Clam Surveys

– Soft shell– Razor shell

Plan Formulation

• Goal– The goal for this feasibility study is to restore

and protect valuable but threatened Mid-Chesapeake Bay island ecosystems through the beneficial use of dredged material.

Plan Formulation• Objectives

Restore and enhance wetland, aquatic and terrestrial island habitat for fish, reptiles, amphibians, birds, and mammals;

Protect existing island ecosystems, including sheltered embayments;

Minimize impacts to fisheries nursery-, feeding-, and protective-habitats;

Increase wetlands acreage in the Chesapeake Bay watershed;

Decrease turbidity and shoreline erosion;

Plan Formulation• Objectives (continued)

Promote conditions that promote the establishment and protection of submerged aquatic vegetation;

Promote conditions that support oyster recolonization;

Minimize impacts to rare, threatened and endangered species and their habitats

Minimize establishment of invasive species; and Allow for placement of 2 million cubic yars/year of

dredge material.

Plan Formulation

• Design Criteria and Constraints• Must protect existing island habitat• Dredge placement depths will be considered

in the range of 7-9 feet.• Footprint should be based on

geomorphology (i.e. clay areas)• Dike heights need to be at a minimum of 10-

12 feet above MLLW.