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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?