New Meadows Lake Tidal Restoration Feasibility Study

March 23, 2006 Second Public Meeting

Sponsored by: Sponsored by: Sponsored by: Sponsored by: With funding provided by:With funding provided by:With funding provided by:With funding provided by:

Study Goal & ObjectivesTo develop and evaluate the feasibility of technical alternatives for improving water quality and enhancing ecological resources in New Meadows Lake through increased tidal exchange.

Public InvolvementPublic Involvement • A key component of the study process and any ultimate decision-making process.A key component of the study process and any ultimate decision-making process.• There will be three public forums during the study.There will be three public forums during the study.• This is the second public forum.This is the second public forum.• The first public forum was held on June 27, 2005.The first public forum was held on June 27, 2005.

Study ProgressStudy ProgressStudy ProgressStudy Progress

1. Temperature and Stage Data

2. Bathymetry Data

3. Conceptual Model Development

4. Preliminary Model Development• Calibration/Validation For Existing Conditions• Evaluation of Phase 1 Alternatives

Bathymetry DataBathymetry Data

• Complete Bathymetry Mapping of Upper and Lower Lake

• Data Corrected for Changes in Tidal Stage

• Data in Maine West 1983 Coordinate Plane

Stage-Volume RelationStage-Volume Relation

Volume (acre-feet)

Elevation(feet)

0 200 400 600 800 1000 1200 140065

70

75

80

85

90

95

100

UpperLowerTotal

Stage DataStage Data– Water Surface Elevations (Stage): New Meadows

River (blue) and New Meadows Lake (red)

Temperature and Stage Data - NMRTemperature and Stage Data - NMRTemperature and Stage Data - NMRTemperature and Stage Data - NMR– Temperature/Pressure Transducers Installed July 29, 2005– Temperature/Pressure Transducers Retrieved October 14, 2005

Temperature and Stage Data - NMLTemperature and Stage Data - NMLTemperature and Stage Data - NMLTemperature and Stage Data - NML

Development of Project AlternativesDevelopment of Project Alternatives• Development and Evaluation of “Conceptual” Alternatives

– Simplified Modeling Approach (“Single Lake”)– Five Conceptual Alternatives were Evaluated to Provide

Information on a Broad Range of Alternatives

• Development and Evaluation of “Preliminary” Alternatives– Refined Modeling Approach (“Upper and Lower Lakes”)– Preliminary Alternatives Largely Based on Conceptual

Alternatives– Six Preliminary Alternatives were Evaluated to Provide

Information on a Broad Range of Alternatives– Evaluated Over Period from September 10 – 24, 2005

Preliminary Alternatives ModelPreliminary Alternatives ModelTidal Stage Data/Calibration and Tidal Stage Data/Calibration and

ValidationValidation

Preliminary Alternatives ModelPreliminary Alternatives ModelTidal Stage Data/Calibration and Tidal Stage Data/Calibration and

ValidationValidation

09 19 29 09 19 29 0901Aug2005 01Sep2005 01Oct2005

84

86

88

90

92

94

96

98

100

102Preliminary Alternative 1

Tim e

ST

AG

E (fe

et)

ST

AG

E (

FE

ET)

Legend

LOWER NML STAGE 06AUG2005 EXSTAU0620

LOWER NML STAGE 10SEP2005 EXSTSEP1024

LOWER NML STAGE 29JUL2005 WAI DATA

NEW MEADOWS RIVER STAGE 29JUL2005 WAI DATA

Miss ing Data

Calibration (Aug 6 – 20, 2005) Validation (Sep 10 – 24, 2005)

Alternative 1: Deeper CulvertAlternative 1: Deeper Culvert

• Existing Culvert Alignment and Width with Invert Set 2.4-ft Below Current Invert

• Lower High Tides (-0.5 ft)• Lower Low Tides (-0.9 ft)• Small Increase in Tidal Range in

Upper and Lower NML (2.4 ft)

Alternative 2: Wider and Deeper Alternative 2: Wider and Deeper CulvertCulvert

• Existing Culvert Alignment, 2x Width with Invert Set 4.5-ft Below Current Invert

• Higher High Tides (~ 1.6 ft) Lower NML• Lower Low Tides (~ -3.5) Lower NML• Increased Tidal Range in Lower NML

(7.1 ft) • Increased Tidal Range in Upper NML

(3.1 ft)

Alternative 3: Two Larger Culverts at Alternative 3: Two Larger Culverts at New LocationNew Location

• Two 24-ft Wide Box Culverts with Inverts Set 7.5-ft Below Current Invert

• Higher High Tides (2.5 ft in Lower NML)• Lower Low Tides (-6.8 ft in Lower NML)• Increased Tidal Range in Lower NML

(11.3 ft) • Increased Tidal Range in Upper NML

(3.5 ft)

Alternative 4: Single Larger Culvert at Alternative 4: Single Larger Culvert at New LocationNew Location

• 24-ft Wide Box Culverts with Invert Set 7.5-ft Below Current Invert

• Higher High Tides (2.1 ft in Lower NML)• Lower Low Tides (-5.9 ft in Lower NML)• Increased Tidal Range in Lower NML

(10.0 ft) • Increased Tidal Range in Upper NML

(3.2 ft)

Alternative 5: Existing + Single Larger Alternative 5: Existing + Single Larger Culvert at New LocationCulvert at New Location

• 24-ft Wide Box Culverts with Invert Set 7.5-ft Below Current Invert

• Higher High Tides (2.1 ft in Lower NML)• Lower Low Tides (-5.9 ft in Lower NML)• Increased Tidal Range in Lower NML

(9.9 ft) • Increased Tidal Range in Upper NML

(3.3 ft)

Alternative 6: BridgeAlternative 6: Bridge

• Bridge with a Bottom Width of 30 ft with Bottom Set Below MLW

• Higher High Tides (2.6 ft in Lower NML)• Lower Low Tides (-7.4 ft in Lower NML)• Increased Tidal Range in Lower NML

(12 ft) • Increased Tidal Range in Upper NML

(3.4 ft)

Comments/Questions?