Tier 1 Water Budget CTC SPC Meeting # 2/09 Agenda Item # 6.1 - - PowerPoint PPT Presentation

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Tier 1 Water Budget

CTC SPC Meeting # 2/09 – Agenda Item # 6.1 February 17, 2009

Gayle SooChan, P.Geo.

Director, Groundwater Resources, CLOCA

Dirk Kassenaar, M.Sc. P.Eng E.J. Wexler, M.Sc., M.Sc. (Eng) CTC Source Protection Region CTC Source Protection Region CTC Source Protection Region CTC Source Protection Region

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CLOSPA Tier 1 Water Budget Process/ Timelines

• Earthfx Inc. – Prepared the T1 Water Budget Study for the CLOCA

jurisdiction – draft completed Jan 08

• Peer Review process initiated Feb 08
• Revised per comments and re-circulated to Peer reviewers for sign-off

Aug 08

• Additional comments received from municipality Oct 08
• Revised per final comments, distributed to SPC Feb 09 for acceptance
• Formal Peer Review Team : Durham Region (Works Dept.),

Papadoupolos & Associates, Dr. R. Gerber, TCC Source Protection Region, Ministry of Natural Resources, Conservation Ontario.

• MOE-CR and LSGB Source Protection Region were also invited to

comment and provided material. No comments were however received.

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Peer Review Comments: on Draft Tier 1

• In our opinion, this is an excellent report that provides a solid

framework for those charged with managing water-resources in the CLOCA area.

• The analyses have been conducted to a high technical standard.
• Peer Reviewers main suggestions for revisions were associated with

some unique methodologies in determination of the groundwater supply factor which affected the stress calculations. The study team was directed to revise the document to ensure provincial consistency in results.

• Revisions/corrections were also made to the PTTW data used by the

review team. These corrections resulted in revised stress calculations.

• Revisions were also made to ensure compliance with the Directors

Rules (changes since the historical technical guidance).

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CLOSPA Tier 1 Water Budget Presentation

• Earthfx Inc.:
• Dirk Kassenaar, M.Sc. P.Eng
• E.J. Wexler, M.Sc., M.Sc. (Eng)

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Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Source Protection Area

Meeting Presentation – February 17, 2009

Dirk Kassenaar, M.Sc., P.Eng. EJ Wexler, M.Sc. M.E. P.Eng. Earthfx Inc. CTC Source Protection Region CTC Source Protection Region CTC Source Protection Region CTC Source Protection Region

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Presentation Outline

• Tier 1 Water Budget Objectives
• Overview of Selected Approach
• Subwatershed assessment areas
• Modelling approach
• CLOCA Watersheds: Overview
• Summary of Tier 1 Water Budget Components
• Water Demand, Supply, Reserve
• Stress Assessment Results
• SGRA Analysis
• Conclusions

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Tier 1 Water Budget: Objectives and Steps

• A Tier 1 water budget is a screening level assessment of water supply and

water demand in the study area

• Identify subwatersheds needing a more detailed assessment
• Calculate “% Water demand” = Water Demand/Supply
• Calculated on annual and monthly basis for both groundwater and

surface water

• Assign a low, moderate or significant “stress” level based on thresholds
• Think Low, Medium or High “Relative Demand Level”
• Thresholds are conservative and meant only for screening
• A Tier 2 is a more detailed and complex assessment to confirm the

stress levels,

• A Tier 3 is needed to actually assess sustainability, risk and

ecological stress

• Additional analysis included in this study:
• SGRA – Significant Groundwater Recharge Areas

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Water Budget Components

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Overview of CLOCA Tier 1 Approach

• Delineate assessment areas (subwatersheds):
• Guidance recommends 20 to 100 km2 assessment area
• Estimate Water Demand:
• Compile MOE permit data, estimate rural and agricultural water use
• Correct water demand for locally returned water (consumptive use) and

seasonal usage patterns

• Estimate Water Supply:
• Tier 1 Guidance allows either spreadsheet or numerical flow model
• Modelling approach selected for CLOCA: adapt existing models
• USGS MODFLOW (groundwater flow model)
• USGS PRMS (Precipitation – Surface Runoff model)
• Calculate % Water Demand and assign stress levels

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CLOCA Subwatersheds: Overview

• Location
• South slope of Oak Ridges Moraine
• Geologic environment
• 1 Minute geologic history of CLOCA
• High recharge Oak Ridges Moraine sediments both within and

just north of CLOCA study area

• Subwatershed Assessment Areas
• Surface watershed boundaries not necessarily groundwater shed

boundaries (lateral groundwater underflow)

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Lynde Oshawa

Bowmanville

Darlington Soper Harmony CLOCA

CLOCA Subwatersheds

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Lynde Oshawa

Bowmanville

Darlington Soper Harmony

Land Use Classification

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Bowmanville

Darlington Soper Harmony

Physiography

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Bowmanville

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Surficial Geology

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Geologic Cross Section

Oak Ridges Aquifer Thorncliffe Aquifer Scarborough Aquifer A B A B

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Subwatershed Assessment Areas

• Assessment area logically selected based on historic

surface water subwatersheds

• Guidance recommends 20 to 100 km2 areas
• Selected areas: 6 to 132 km2
• However: surface watershed boundaries not always a

good indication of groundwatershed boundaries

• Multiple aquitard layers isolate the lower aquifers,

allowing underflow

• Model area extends beyond CLOCA boundaries to allow

calculation of lateral inflows

• Note: Some other studies have assumed that lateral

inflows are negligible at a Tier 1 assessment level

Area km2 Lynde Creek 132 Pringle Creek 28 Corbett Creek 15 Goodman Creek 10 Oshawa Creek 110 Harmony Creek 47 Farewell Creek 36 Robinson Creek 6 Tooley Creek 11 Black Creek 24 Darlington Creek 16 Bowmanville Creek 90 Westside Creek 6 Soper Creek 75 Bennet Creek 7 Lake Catchments 24 Watershed

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Model Area

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WATER DEMAND ESTIMATES

Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Source Protection Area Source Protection Area

18

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Consumptive Demand Estimate

• Definition: Consumptive demand is the amount of water that is not

returned to its original source.

• Data Sources:
• MOE permit data
• Where possible confirmed by CLOCA
• Assumed maximum rate, but adjusted for seasonal use
• Actual use data not available from MOE
• Estimates of rural (un-serviced) demand: current and future
• Non-permitted agricultural water use
• Estimate based on MOE water well usage codes (irrigation,

livestock, orchard, etc. )

• Expired or possible permits: estimated usage
• Golf courses with no known permit: estimated usage

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Consumptive Demand Estimate Corrections

• Seasonal usage correction
• Many permits are for a limited number of days per year.
• Logically allocated over the appropriate months
• Even if the permit was issued for 365 days, seasonal usage was

estimated based on permit use (golf course, snowmaking)

• Consumptive Use: Locally returned water
• Tier 1 allows different consumptive approaches: watershed,

aquifer, etc.

• CLOCA Assessment: Assumed all water consumptive relative to

the watershed

• Conservative assumption: Return rates taken from MOE

guidance (Golf course: 70% consumptive)

• Other Tier 1 studies have assumed pumping from deep

aquifers would be 100% consumptive

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Overall Groundwater Demand: By Usage

. 1 % . % . % 9 . 8 %

• S

n

• w

m a k i n g 5 . 4 %

• D

e w a t e r i n g 5 8 . 6 %

• U

n p e r m i t t e d A g . 2 . 6 %

• G
• l

f . 1 % 5 . 4 %

• U

n s e r v i c e d C

• n

s u m p t i

• n

Concrete Plant / Drinking Dewatering Golf Course Irrigation Maintenance Other- Commercial Snowmaking Water Supply Unpermitted Agricultural Unserviced Consumption

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Total Groundwater Demand: By Subwatershed

2% 0% 0% 4% 5% 1% 2% 3% 1% 1% 1% Darlington 7% Soper 8% Oshawa 14% Bowmanville 11% Lynde , 39% Lynde Pringle Corbett Goodman Oshawa Harmony Farewell Robinson Tooley Black Darlington Bowmanville Westside Soper Bennett Lake Ontario

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Consumptive Demand Estimate: Conclusions

• The consumptive demand estimate is quite uncertain:
• Actual permitted water use is not know at this time
• Unserviced population and non-permitted agricultural use is

estimated

• However: There are no municipal groundwater users in the study

area

• No Tier 2 level assessment will therefore be required.

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WATER SUPPLY ESTIMATES

Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Source Protection Area Source Protection Area

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Water Supply Estimate

• Recharge Estimate
• USGS Precipitation Runoff Modelling System (PRMS)
• Primarily to estimate groundwater recharge
• Calibrate to streamflow estimates at gauges, with underflow

corrections estimated from GW model

• Lateral Inflows (Qin)
• USGS MODFLOW model: GW flux crossing the subwatershed

boundary

• Water Reserve
• Estimated as 10% of the baseflow discharge, as estimated by

the MODFLOW Model

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Lynde Oshawa

Bowmanville

Darlington Soper Harmony

Estimated GW Recharge

Note high recharge immediately north

• f study area

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GW Levels in Lower Aquifer

Used to estimate lateral flow rates

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GW Discharge to Streams

Used to estimate baseflow reserve

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Subwatershed Stress Assessment

Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Source Protection Area Source Protection Area

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% Water Demand = QDEMAND x 100 QSUPPLY - QRESERVE 0 - 19 % Low Low ≥ 20% Moderate Moderate ≥ 50% Significant Significant

Maximum Monthly % Water Demand Stress Level Assignment

0 - 24% 0 - 9% Low Low ≥ 25% ≥ 10% Moderate Moderate ≥ 50% ≥ 25% Significant Significant

Maximum Monthly % Water Demand Average Annual % Water Demand Stress Level Assignment

Groundwater Stress Levels Surface Water Stress Levels

Tier 1 Tier 1 – – Stress Levels Stress Levels

Note: Qsupply = Qrecharge + Q lateral inflow

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Percent Water Demand Results

Watershed Q Recharge (m3/s) Q In (m3/s) Q Supply (m3/s) Q Reserve (m3/s) Q Demand Current Condi- tions (m3/s) % Water Demand Current Condi- tions Stress Level Current Conditions Lynde Creek 0.6765 0.2020 0.8785 0.0679 0.0819 10.10 Moderate Pringle Creek 0.1115 0.0420 0.1535 0.0106 0.0043 2.98 Low Corbett Creek 0.0463 0.0170 0.0633 0.0041 0.0001 0.19 Low Goodman Creek 0.0462 0.0150 0.0612 0.0024 0.0009 1.48 Low Oshawa Creek 0.5892 0.1970 0.7862 0.0650 0.0300 4.17 Low Harmony Creek 0.1756 0.0810 0.2566 0.0175 0.0095 3.95 Low Farewell Creek 0.1577 0.1100 0.2677 0.0168 0.0100 4.00 Low Robinson Creek 0.0193 0.0150 0.0343 0.0004 0.0023 6.89 Low Tooley Creek 0.0423 0.0200 0.0623 0.0028 0.0038 6.30 Low Black Creek 0.1243 0.0670 0.1913 0.0106 0.0062 3.44 Low Darlington Creek 0.0702 0.0220 0.0922 0.0043 0.0149 16.97 Moderate Bowmanville Creek 0.6149 0.3050 0.9199 0.0816 0.0239 2.85 Low Westside Creek 0.0180 0.0220 0.0400 0.0013 0.0015 3.76 Low Soper Creek 0.4152 0.2000 0.6152 0.0407 0.0170 2.97 Low Bennet Creek 0.0272 0.0210 0.0482 0.0018 0.0018 3.82 Low Lake Catchments 0.0747 0.1100 0.1847 0.0086 0.0032 1.79 Low

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Stress Assessment Results:

• Lynde Creek: Moderate stress level
• Golf courses
• Snowmaking operations
• Darlington Creek: Moderate stress level
• Quarry operation in lower subwatershed
• No municipal supply in either subwatershed, therefore no Tier 2

needed

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Stress Assessment Results: Lateral Inflows

• Lateral inflows are equal to between 30% and 144% of the

groundwater recharge

• Qin is a significant portion of GW supply term
• Need to “think outside the watershed” when looking at CLOCA

Q Q Ratio of Area Recharge In Qin/Qrecharge km2 (m3/s) (m3/s) Percent Lynde Creek 132 0.677 0.202 30% Pringle Creek 28 0.112 0.042 38% Corbett Creek 15 0.046 0.017 37% Goodman Creek 10 0.046 0.015 32% Oshawa Creek 110 0.589 0.197 33% Harmony Creek 47 0.176 0.081 46% Farewell Creek 36 0.158 0.110 70% Robinson Creek 6 0.019 0.015 78% Tooley Creek 11 0.042 0.020 47% Black Creek 24 0.124 0.067 54% Darlington Creek 16 0.070 0.022 31% Bowmanville Creek 90 0.615 0.305 50% Westside Creek 6 0.018 0.022 122% Soper Creek 75 0.415 0.200 48% Bennet Creek 7 0.027 0.021 77% Lake Catchments 24 0.075 0.110 NA Watershed

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Lynde Oshawa

Bowmanville

Darlington Soper Harmony

GW Supply

Higher supply in subwatersheds that reach the ORM

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Percent GW Demand

Higher Percent demand in Lynde and Darlington

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Lynde Oshawa

Bowmanville

Darlington Soper Harmony

Tier 1 Stress Level

Lynde and Darlington exhibit moderate GW stress

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SW Stress Level

SW Stress levels based

• n high demand during

low summer flows

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Stress Assessment: Conclusions

• Lynde and Darlington Creeks classified as moderate stress level
• No municipal groundwater supply, therefore no need to proceed

to a Tier 2 assessment

• Considerable uncertainty in the water demand estimates
• Advanced modelling techniques used to estimate water supply
• Modelling analysis essentially at a Tier 2 level
• Lateral groundwater inflows account for a significant portion of the

water supply term

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Comments on Stress Assessment: Field Verification

• Cumulative flow analysis of stream gauge data can indicate if stress is real
• Example: Cumulative flow for Oshawa Creek: 1959-2003
• Deviation from linear trend suggests increasing consumptive stress

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Significant Recharge Areas

Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Source Protection Area Source Protection Area

40

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SGRA: Significant Groundwater Recharge Areas

• SGRA and High Volume Recharge Areas (HVRA) calculated using a

number of guidance recommended methods

• Cell-based PRMS Recharge estimate can be adapted and re-

processed with different threshold levels to estimate SGRA areas

• Need to consider:
• Shallow versus deep groundwater flow system
• Municipal water supply source must be considered in defining

significance

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The Technical Rules prescribe the following equations.

Part V.2 - Delineation of significant groundwater recharge areas

• 41. Subject to rule 42, an area is a significant groundwater recharge area if,

(1) the area annually recharges water to the underlying aquifer at a rate that is greater than the rate of recharge across the whole of the related groundwater recharge area by a factor of 1.15 or more; or (2) the area annually recharges a volume of water to the underlying aquifer that is 55% or more of the volume determined by subtracting the annual evapotranspiration for the whole of the related groundwater recharge area from the annual precipitation for the whole of the related groundwater recharge area.

• 42. Despite rule 41, an area shall not be delineated as a significant groundwater

recharge area unless the area has a hydrological connection to a surface water body or aquifer that is a source of drinking water for a drinking water system.

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SGRA: Method 4

SGRA

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Bowmanville

Darlington Soper Harmony

SGRA: Method 5

SGRA

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SGRA: Particle Tracking

Reverse particle tracking from high discharge stream reaches illustrates SGRAs and significant underflow

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SGRA Conclusions

• PRMS Recharge Model indicates that recharge is highly variable on both

a seasonal and spatial basis

• SGRA analysis cannot simply look at surficial materials:
• Shallow Iroquois Beach sand deposits in the southern portion are thin

and not directly connected to the deeper aquifer system

• Particle tracking indicates:
• Significant recharge occurs outside of the study area
• Underflow is important: Bowmanville discharge can be traced under

Soper Creek to a recharge location outside of the subwatershed.

• SGRA Thresholds can be adjusted as necessary

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CONCLUSIONS

Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Draft Accepted Tier 1 Water Budget for the Central Lake Ontario Source Protection Area Source Protection Area

47

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Tier 1 Water Budget Report Conclusions

• Lynde and Darlington Creeks classified as Moderate Stress Level under

current and future demand conditions.

• No municipal groundwater sources exist in these subwatersheds
• Tier 2 level analysis is not needed.
• Considerable uncertainty in the water demand estimates. Major uses:
• Non-permitted agricultural: 59%
• Golf courses: 21%
• Snowmaking: 10%
• Dewatering: 5%
• Need to confirm actual water use from MOE and other sources