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1. Assessing Cumulative Effects of SAGD
Operations in the Mackay Watershed
Dirk Kassenaar, E.J. Wexler, P.J. Thompson, M. Takeda
Earthfx Inc.
Watertech 2016
April 7, 2015

2. Review of Cumulative Impacts – MacKay River Watershed
Introduction
 In-situ Steam Assisted Gravity
Drainage (SAGD) oil sand
operations require a source of fresh
water for steam injection.
 Groundwater supply wells,
generally drawing from aquifers
above the oil production zone, are
a preferred source.
2- Introduction
From MEG Energy Corp.

3. Review of Cumulative Impacts – MacKay River Watershed
Study Objectives
 In 2014, Earthfx Inc. was hired by the Cumulative Environmental Management
Association (CEMA) to answer the following question:
▪ Is there enough water in the Mackay watershed to sustain a responsible
level of development
 Cumulative effects analysis requires the integrated assessment of:
▪ Multiple anthropogenic stresses:
• Numerous spatially distributed SW and GW diversions
• Land use change (land clearing, drill pads, roads, etc.)
▪ Intersecting effects on surface and groundwater systems:
• Changes in groundwater levels (drawdowns) in all aquifer systems
• Changes to frequency, duration and severity of low flow conditions
3- Introduction

4. Review of Cumulative Impacts – MacKay River Watershed
Study Area
 MacKay River Watershed is
located immediately north-west of
Fort McMurrray, AB
▪ Includes Syncrude Mine site and
numerous SAGD operations
 Watershed Area: 5,600 km2
 Model Area: 7,900 km2
4- Summary of Model Development
Legend
Lake
Namur
Lake

5. Review of Cumulative Impacts – MacKay River Watershed
Study Approach
 Step 1: Integrated Model Development and Calibration
▪ Model Development: Compile Geology, Hydrogeology, Climate, Hydrology, Hydraulics
▪ Model Calibration:
• Build and pre-calibrate the SW and GW submodels
• Complete the fully integrated model calibration: Full reconciliation of entire hydrologic cycle water budget
 Step 2: Sustainability Assessment
▪ Define Assessment Criteria and Climate Period
• Define aquifer drawdown and streamflow impact sustainability thresholds
• Select a representative “surrogate” climate assessment period (25 years)
▪ Simulate Pre-development (Baseline), Current and Full Build conditions over the climate period
▪ Compare, on a daily basis, Current and Full-build conditions against Baseline
• Evaluate GW drawdowns and streamflow changes against Assessment Criteria
5- Introduction

6. Review of Cumulative Impacts – MacKay River Watershed
Review of Cumulative Impacts – MacKay River Watershed
MODELLING APPROACH
6- Modelling Approach

7. Review of Cumulative Impacts – MacKay River Watershed
Integrated Modelling Approach: Advantages
 Study Approach: Fully integrated surface water and groundwater model
 Better representation of:
▪ Groundwater recharge and
Dunnian GW feedback
▪ Streamflow and induced leakage
▪ SW/GW storage
▪ Cumulative effects of all SW and
GW diversions
 Flux inputs and calibration targets
▪ Measured precipitation as input
▪ Calibration to total streamflow and
measured GW levels
7- Modelling Approach

8. Review of Cumulative Impacts – MacKay River Watershed
Selected Model: USGS GSFLOW
 USGS integrated GW/SW model
▪ Based on MODFLOW-NWT and PRMS (Precipitation-Runoff Modelling System)
▪ Open-source, proven and very well documented
▪ Fully-distributed: Cell-based representation
▪ Excellent balance of hydrology, hydraulics and GW
8- Modelling Approach

9. Review of Cumulative Impacts – MacKay River Watershed
Review of Cumulative Impacts – MacKay River Watershed
SUMMARY OF MACKAY
MODEL DEVELOPMENT
9- Summary of Model Development

10. Review of Cumulative Impacts – MacKay River Watershed
Study Area Features
 Topography (600 m of relief)
▪ Birch Mountains
▪ Thickwood Hills
 Incised river and stream network
▪ MacKay River – main channel
▪ Dover and Dunkirk Tributaries
▪ Athabasca River: South and eastern boundary
 Legend and Namur Lakes
▪ Plus over 100 other lakes in study area
 Extensive muskeg and wetlands
 Bedrock Channel Aquifers
▪ Key GW supply source for multiple projects
 Anthropogenic Stresses
▪ Syncrude Mine
▪ SW and GW Diversions
10- Summary of Model Development
AMBI, 2013)

11. Review of Cumulative Impacts – MacKay River Watershed
GSFLOW: Multi-Resolution
 GSFLOW is unique in that the
resolution of the model can be
adjusted to match key features
11
Climate inputs
( 2.5 km cells)
Surface Hydrology/Soil Zone
( 200x200 m cells)
Sub-surface Hydrogeologic Layers
( 13 layers of 400x400 m cells)
Stream Network
Linear 1-D Channel segments
(4000 km of streams represented,
independent of grid resolution)
- Summary of Model Development

12. Review of Cumulative Impacts – MacKay River Watershed
Model Grid
 Fully distributed model: Every
cell has unique properties
 GW grid: 400 m by 400 m cells
▪ Selected to match assessment
averaging criteria (impact at 150 m
from a well) but avoid focus on
specific water users.
▪ Can be refined for future studies
 SW Grid: 200x200 m cells
▪ Improved representation of overland
flow, wetlands, interflow and soil
zone processes and properties
 Stream routing:
▪ All streams and rivers simulated
12- Summary of Model Development
400x400 m GW grid

13. Review of Cumulative Impacts – MacKay River Watershed
Geologic Setting
13- Summary of Model Development
Surficial Geology Bedrock Geology
Predominantly tills
and glaciolacustrine
deposits
Subcrop of units
that dip to the
southwest

14. Review of Cumulative Impacts – MacKay River Watershed
Geologic Information
14- Summary of Model Development
 Primary sources for geologic
borehole data:
25,000 - Alberta Geological Survey
255 - Atlas (Western Canada
Sedimentary Basin)
 Limited geologic data in Birch
Mountains and central portion of
study area

15. Review of Cumulative Impacts – MacKay River Watershed
Conceptual Stratigraphic Model
15- Summary of Model Development
After AGS Source: Andriashek and Atkinson, 2007
Empress Channel Sands:
Key water supply aquifer

16. Review of Cumulative Impacts – MacKay River Watershed
Hydrostrat. Layers
16- Summary of Model Development
 19 layer strat. model used to
produce 17 layer hydrostrat.
model.
▪ Some units of similar hydraulic
properties were combined.
▪ McMurray Basal Sands added as
separate aquifer unit.
 Model does not extend below
Prairie Fm. Aquiclude
▪ Assumed minimal communication
due to low vertical K of unit.
▪ Simulating higher salinities (>50,000
mg/L TDS) would require density
dependent groundwater flow.
Period Unit
Stratigraphic
Model
Unit
Hydrostratigraphic
Model
Quaternary
1 Late Lacustrine 1 Aquitard
2 Surface Sand 2 Aquifer
3 Grand Centre Till 3 Aquitard
4 Middle Sands 4 Aquifer
5 Intermediate Till 5 Aquitard
6 Empress Channel Sands 6 Aquifer
Cretaceous
7 Labiche Formation 7 Aquitard
8 Pelican/Viking Formation 8 Aquifer
9 Joli Fou Formation 9 Aquitard
10 Grand Rapids Formation 10 Aquifer
11 Clearwater Formation
11 Aquitard
12 Wabiskaw Formation
13
McMurray Formation
(includes Basal Sands)
12 Aquitard
13 Basal Sand Aquifer
Devonian
14 Winterburn Formation (not included)
15 Grosmont Formation 14 Aquifer
16 Lower Ireton Formation 15 Aquitard
17 Cooking Lake Formation 16 Aquifer
18 Beaverhill Lake Group 17 Aquitard
19
Watt Mountain Formation
(Top of Elk Point Group)
Base of Model
Prairie Formation
(not included)
Keg River Formation
Contact Rapids Formation
Laloche Formation
Precambrian

17. Review of Cumulative Impacts – MacKay River Watershed
GW Level Data
 803 wells with water level data
 Well assigned to hydrostrat. units
based on screened intervals.
 Limited long term temporal
monitoring data (GOWN)
17- Summary of Model Development

18. Review of Cumulative Impacts – MacKay River Watershed
Groundwater Submodel Calibration
18- Summary of Model Development
Unit
Number of
Wells
(n)
ME
(m)
MAE
(m)
RMSE
(m)
Range in
Observations
(m)
RMSE as
Percent of
Range
(%)
Overburden 236 -1.36 4.40 7.18 509.4 1.4%
Empress 58 -7.01 8.33 2.89 189.5 1.5%
Labiche 4 24.50 25.53 32.78 176.3 18.6%
Viking 42 -9.04 10.67 12.65 38.9 32.5%
Joli Fou 10 -5.24 9.44 10.46 28.5 36.8%
Grand Rapids 53 -8.45 8.58 11.58 94.7 12.2%
Clearwater 114 -5.55 8.97 12.06 188.6 6.4%
McMurray 71 0.56 11.47 19.50 279.7 7.0%
Cooking Lake 2 62.09 89.00 108.52 198.3 54.7%
Overall 590 -3.35 7.86 13.55 524.6 2.6%
200
300
400
500
600
700
800
200 300 400 500 600 700 800
Simulated(masl)
Observed (masl)
Overburden
Empress Fm.
Labiche Aquitard
Viking Aquifer
Joli Fou Aquitard
Grand Rapids Aquifer
Clearwater Aquitard
McMurray Aquifer/Aquitard
Cooking Lake Aquifer
1:1
Error Intervals (±10 m)
 Steady-state submodel calibration.
 Better calibration in aquifers where
data more plentiful.

19. Review of Cumulative Impacts – MacKay River Watershed
Hydrologic Submodel Development (PRMS)
 Based on the USGS
Precipitation-Runoff Modeling
System (PRMS) code
 Fully distributed implementation
 200m x 200m cells (196,832
unique cell HRUs)
19- Summary of Model Development
In each unique cell:

20. Review of Cumulative Impacts – MacKay River Watershed
Climate Inputs
 Precipitation and temperature
interpolated on a daily basis over a
2.5km x 2.5km grid
▪ Inverse distance squared weighting
 25 year daily climate time series
input for each grid cell
20- Summary of Model Development

21. Review of Cumulative Impacts – MacKay River Watershed
Vegetative Cover Classes
 26 wetland and vegetative cover classes
▪ 17 types of wetlands
 Model parameters assigned by class:
▪ Seasonal Cover density
▪ Vegetation indices
▪ Soil zone properties
▪ Overland flow and shallow interflow parameters
21- Summary of Model Development

22. Review of Cumulative Impacts – MacKay River Watershed
Overland Flow
 Overland flow and interflow simulated with a
topographically defined cascade network
 200x200m cell representation
22- Summary of Model Development

23. Review of Cumulative Impacts – MacKay River Watershed
Lateral Flow Processes
23- Summary of Model Development
PRMS
Soil Zone
MODFLOW
Layer 1
MODFLOW
Layer 2
• Head Dependant
• Saturation Dependant

24. Review of Cumulative Impacts – MacKay River Watershed
Dunnian Flow Processes: SW/GW Feedback
24- Summary of Model Development
 Groundwater feedback dominates in discharge areas, wetlands and shallow aquifers
▪ GW feedback in up to 60% of the watershed
 Complex transient runoff and rejected recharge
▪ Occurs when the water table is at or near surface
▪ Spatially controlled: Tends to occur in stream valley areas
▪ Seasonally controlled: Tends to occur in spring when WT is high
 GW discharge to the soil zone can become interflow or overland flow
 Overland flow can re-infiltrate downslope: “3D recharge”
Unsaturated
zone
StreamStream
Gravity drainage
Recharge
Ground-water flow

25. Review of Cumulative Impacts – MacKay River Watershed
Frozen Ground
 New frozen ground module developed for
this study
▪ GSFLOW is Open Source!
 Based on a modified form of the Stefan
Equation
▪ Derived by the U.S. Army Corps of Engineers
 Model code follows Emerson (1994)
25- Summary of Model Development
𝑋𝑓 =
86,400𝐾𝑓 𝐼𝑓
𝐿 + 𝐶 𝑇𝑎 +
𝐼𝑓
2𝑡
0.5
𝑋𝑓 = 𝑑𝑒𝑝𝑡ℎ 𝑜𝑓 𝑓𝑟𝑜𝑠𝑡
𝐾𝑓 = 𝑡ℎ𝑒𝑟𝑚𝑎𝑙 𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦
𝐼𝑓 = 𝑓𝑟𝑜𝑠𝑡 𝑖𝑛𝑑𝑒𝑥 𝑑𝑒𝑔𝑟𝑒𝑒 𝑑𝑎𝑦𝑠
𝐿 = 𝑙𝑎𝑡𝑒𝑛𝑡 ℎ𝑒𝑎𝑡
𝐶 = 𝑣𝑜𝑙𝑢𝑚𝑒𝑡𝑟𝑖𝑐 ℎ𝑒𝑎𝑡 𝑐𝑎𝑝𝑐𝑖𝑡𝑦
𝑇𝑎 = 𝑚𝑒𝑎𝑛 𝑎𝑛𝑛𝑢𝑎𝑙 𝑠𝑜𝑖𝑙 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒
𝑡 = 𝑑𝑢𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑡ℎ𝑒 𝑓𝑟𝑒𝑒𝑧𝑖𝑛𝑔 𝑝𝑒𝑟𝑖𝑜𝑑
𝑤ℎ𝑒𝑟𝑒

26. Review of Cumulative Impacts – MacKay River Watershed
Frozen Ground Response
 Frozen soil dynamics affect both surface and subsurface processes:
▪ SW Runoff and Recharge: Enhanced runoff during spring freshet, no winter recharge
▪ GW Discharge: Significantly reduced winter discharge to streams and wetlands
26- Summary of Model Development

27. Review of Cumulative Impacts – MacKay River Watershed
Model Calibration and Validation
 Calibrated then verified against over 38 year period
 A range of hydroclimatic conditions simulated
27- Summary of Model Development
Validation Calibration

28. Review of Cumulative Impacts – MacKay River Watershed
Model Calibration and Validation
 Hydrologic submodel and the final
integrated model were calibrated
against streamflow observations at 6
Water Survey (EC) and RAMP
stations
 Historical observations at
discontinued stations were an
important source of insight
28- Summary of Model Development

29. Review of Cumulative Impacts – MacKay River Watershed
Model Calibration and Validation
 Good match to streamflow
observations at study area gauges
 Daily Nash-Sutcliffe 0.65
 Monthly Nash-Sutcliffe 0.75
 Good match to validation period:
Model has adequate predictive
power
29- Summary of Model Development

30. Review of Cumulative Impacts – MacKay River Watershed
Distributed Results
30- Summary of Model Development

31. Review of Cumulative Impacts – MacKay River Watershed
Distributed Results (GSFLOW)
31- Summary of Model Development

32. Review of Cumulative Impacts – MacKay River Watershed
GSFLOW GW/SW Outputs
32- Summary of Model Development
April May

33. Review of Cumulative Impacts – MacKay River Watershed
GW/SW Animation
 Animation shows spring
melt and changes in GW
levels and streamflow
 Click for Animation
33- Summary of Model Development

34. Review of Cumulative Impacts – MacKay River Watershed
GSFLOW Outputs
 Spring change in water
levels and streamflow
34- Summary of Model Development

35. Review of Cumulative Impacts – MacKay River Watershed
GSFLOW Outputs
 Spring change in water
levels and streamflow
 Click for Animation
35- Summary of Model Development

36. Review of Cumulative Impacts – MacKay River Watershed
GSFLOW GW/SW Water Budgets
Significant inter-annual and seasonal storage effects.
36- Summary of Model Development
-4
-3
-2
-1
0
1
2
3
4
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg
Flows(mm/month)
Monthly Average GW Inflows and Outflows - Pre-Development Conditions
Lake Seepage Stream Leakage Surf Leakage Recharge Wells Net Const. Head Net Storage
-20
-15
-10
-5
0
5
10
15
20
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Flows(mm/yr)
Simulated Inflows and Outflows by Water Year - Pre-Development Conditions
Lake Seepage Stream Leakage Surface Leakage Recharge Wells Net Const. Head Net Storage

37. Review of Cumulative Impacts – MacKay River Watershed
Model Development Conclusions
 The Mackay GSFLOW model represents the complex transient surface
and subsurface process and their interaction and feedback
 Extensive submodel development and integrated model calibration was
undertaken to all available data
 Key aspect of the integrated model calibration:
▪ Directly measured flux input: Precipitation
▪ Directly observed calibration targets: Total measured streamflow and GW heads
▪ Overall water budget must balance – no water is gained or lost
37- Summary of Model Development

38. Review of Cumulative Impacts – MacKay River Watershed
Review of Cumulative Impacts – MacKay River Watershed
ASSESSMENT SCENARIOS:
CRITERIA AND RESULTS
38- Assessment Scenarios

39. Review of Cumulative Impacts – MacKay River Watershed
Diversion Scenarios
 Baseline: No pumping
 Current Conditions:
▪ 4 Operations including 11
pumped wells.
 Full-Build Conditions:
▪ 14 Operations including 42
pumped wells.
39- Assessment Scenarios
Current
Operations
Current
Operations
Current
Operations

40. Review of Cumulative Impacts – MacKay River Watershed
Land Use Change
 Processing facilities and well pads
▪ Assumed to be 100m by 100m gravel
pads spaced 500m on center
▪ Reduced ET, due to the loss of vegetation,
increased runoff
 Full Build Scenario:
▪ Drill pads are estimated to cover 6% of
the planned project areas;
▪ Roads, pipelines, and facilities cover
another 4%.
40- Recommendations for Phase 3

41. Review of Cumulative Impacts – MacKay River Watershed
Assessment Climate Period
 25 year period includes a range of hydroclimatic conditions
▪ Includes both wet years (1997) and drought years (1998-1999, 2009 and 2011).
▪ 5 year spin-up period before start of assessment
41
Surrogate Climate Period
- Assessment Scenarios

42. Review of Cumulative Impacts – MacKay River Watershed
GW Sustainability Assessment Criteria
 In summary, it was agreed that the sustainable drawdown is 50% of the available
drawdown in a confined aquifer.
▪ Threshold selection based on the Alberta Environment Water Conservation and Allocation Guideline for Oilfield
Injection (AENV, 2006)
▪ For unconfined aquifers, 66% of the average saturated thickness was used.
▪ Available drawdown based on average water level determined by 20 year baseline simulation.
 Assessment Process: all three scenarios run using the same climate inputs
▪ Only difference is diversions and land use change
▪ Daily outputs for every model cell and stream reach saved for comparison
• Drawdown calculation
• Alberta Desktop Assessment
 If, under Current or Full-build development conditions, drawdowns exceeded this
threshold on any particular day in a 20 year assessment simulation, the cumulative
diversion was considered locally unsustainable.
42- Assessment Scenarios

43. Review of Cumulative Impacts – MacKay River Watershed
Overburden Impacts
43- Assessment Scenarios
Overburden Aquifers
Layer 1 Drawdowns
Percent of Total
Available Drawdown

44. Review of Cumulative Impacts – MacKay River Watershed
Channel Aquifers
44- Assessment Scenarios
Empress Formation Aquifer
Layer 4 Drawdowns
Percent of Total
Available Drawdown

45. Review of Cumulative Impacts – MacKay River Watershed
Confined Aquifers
45- Assessment Scenarios
Viking/Pelican Aquifer
Layer 5 Drawdowns
Percent of Total
Available Drawdown

46. Review of Cumulative Impacts – MacKay River Watershed
Deep Aquifers
46- Assessment Scenarios
Grand Rapids Aquifer
Layer 8 Drawdowns
Percent of Total
Available Drawdown

47. Review of Cumulative Impacts – MacKay River Watershed
GW Sustainability Assessment
 Cumulative GW drawdowns are significant, in particular in the lower
highly confined aquifer units
▪ Offset by the fact that lower units have much greater available drawdown
 On a watershed scale, GW drawdowns appear to broadly stabilize
within the 20 year period, suggesting sustainable water use
 Localized zones where drawdown exceed 50% of total available
drawdown
47- Assessment Scenarios

48. Review of Cumulative Impacts – MacKay River Watershed
SW Sustainability Assessment Criteria
 Alberta Desktop Method:
▪ Simulated frequency-duration relationship is calculated for every reach under baseline conditions
▪ The discharge that is exceeded 80% of the time is the ecosystem baseflow (EBF) component.
 ADM Criteria 1:
▪ No surface water diversions are allowed below the 80% EBF threshold
• No diversion allowed when flow is below the lowest flows that occur up to 20% of the time.
 ADM Criteria 2:
▪ Above the 80% EBF threshold, up to 15% of the available flow can be diverted.
 20 year Baseline simulation used to determine weekly EBF threshold in every stream reach
48- Assessment Scenarios

49. Review of Cumulative Impacts – MacKay River Watershed
SW Sustainability Assessment Criteria
 Frequency-duration relationship calculated in the watercourse in a
natural state.
 EBF Weekly Threshold for Mackay River at Fort McKay:
49- Assessment Scenarios

50. Review of Cumulative Impacts – MacKay River Watershed
SW Sustainability Assessment
 Threshold for Mackay River at Fort McKay shown
▪ ADM Criteria 1 - fails for select days, as shown in red
▪ ADM Criteria 2 - never more than 15% diverted
 Numerous other stream locations also assessed
50- Assessment Scenarios

51. Review of Cumulative Impacts – MacKay River Watershed
Local SW Effects
 While the overall watershed
passes the ADM criteria at the
Mackay outfall point, local streams
fail the 15% ADM criteria
▪ i.e. GW diversions locally induce
leakage that exceeds 15% of the EBF
(ecological baseflow)
51- Assessment Scenarios

52. Review of Cumulative Impacts – MacKay River Watershed
Sustainability Assessment Conclusions
 In summary, the analysis indicates that projected water use in the study area is broadly
sustainable, from both a groundwater and surface water aspect, on a watershed scale.
 This conclusion is supported by two findings:
▪ Results indicate that drawdowns do not, on a watershed scale, appear to grow over time
▪ Accumulated streamflow losses do not exceed the 15% ADM threshold along the main channel of the Mackay
and Dover Rivers.
 The results do indicate, however, that under the full build scenario, cumulative
groundwater diversions appeared to create unsustainable local impacts, as measured by
both the groundwater drawdown and ADM thresholds.
52- Assessment Scenarios

53. Review of Cumulative Impacts – MacKay River Watershed
Water Budget Comparisons
53- Assessment Scenarios
-20
-15
-10
-5
0
5
10
15
20
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Flows(mm/yr)
Simulated Inflows and Outflows by Water Year - Pre-Development Conditions
Lake Seepage Stream Leakage Surface Leakage Recharge Wells Net Const. Head Net Storage
-20
-15
-10
-5
0
5
10
15
20
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Flows(mm/yr)
Simulated Inflows and Outflows by Water Year - Full Build Conditions
Lake Seepage Stream Leakage Surface Leakage Recharge Wells Net Const. Head Net Storage
 Pre-development shows how wet and dry years replenish and deplete storage (royal blue)
 Full build scenario shows greater fluctuations in storage

54. Review of Cumulative Impacts – MacKay River Watershed
Water Budget Comparisons
 Winter pumping depletes storage, replenished by April recharge.
54- Assessment Scenarios
Full-Build ConditionsBaseline Conditions

55. Review of Cumulative Impacts – MacKay River Watershed
Other Insights
 Winter pumping under frozen ground
conditions depletes shallow aquifer storage
 Baseflow discharge in May is reduced by
50% due to freshet replenishment of shallow
aquifer storage.
 Understanding seasonal and inter-annual
storage is essential
55- Assessment Scenarios
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
AverageMonthlyGroundwaterDischargeto
Streams(mm/year)
Pre-Development
Full Build
Average Monthly GW
Discharge to Streams

56. Review of Cumulative Impacts – MacKay River Watershed
Overall Conclusions
56- Recommendations for Phase 3
 Detailed, fully integrated SW/GW modelling can provide significant insight
into both cumulative effects and watershed function.
 Numerous applications – Local impact assessment, water budgeting,
climate change, drought assessment, eco-hydrology and water
management.