Transcript Slide 1

Truckee River Water Quality
Standards Review
Focus Group Meeting: July 17, 2013
Overview of Topics for Discussion
• Recap on Water Quality Models to Support
WQS Review
– Recent updates
– Model confirmation report
• Overview of general approach for WQS
modeling
• Technical decision points
• Anticipated schedule and milestones
2
Recap on Water Quality Models to
Support WQS Review
Intended Use of Models
• Explore river water quality response to ranges of
point and nonpoint concentrations/loads under
range of flow conditions
• Model results support review of WQS and TMDL
– WQS: establish site-specific response to nutrient
concentrations
– TMDL: help understand possible balances of point and
nonpoint loads which result in DO WQS attainment
4
Model Linkage for Truckee River
WQS Analysis
Demands,
Water Operations,
In-stream Flow Targets
TROM
Reservoir
Releases,
Diversions
Meteorology, Land Use, TMWRF
Effluent and Re-use
WARMF
Diversions
TMWRF Effluent
Tributary Flows,
Nonpoint Sources
TRHSPF
In-stream
Water
Quality
WARMF: Watershed Model
• Peer reviewed, public
domain
• Predicts watershed flow and
pollutant loads based on
–
–
–
–
• 125 catchments
(subwatersheds)
• Time step = 1 day
land use
meteorological conditions
water management
watershed improvements
6
TRHSPF: River Water Quality Model
•
•
•
•
•
Based on DSSAMt science (used for 1994 TMDL)
Open code, EPA-supported, peer reviewed
Calibrated and verified, technology transferred
Inputs are flow, watershed loads, point sources
Predicts:
– water quality response of river
– nutrients  periphyton  dissolved oxygen
7
Recap of 2011 Model Extension/Update
• Updated both WARMF and TRHSPF
– Extended databases through 12/31/2008
– Models reflect rapid regional growth through 2006
– Refined calibration
• Model limitations identified in 2011
– Under-prediction of snow melt peaks in wetter years (WARMF)
– Under-prediction of flow in Steamboat Creek and North Truckee Drain
during summer due to landscape irrigation with potable/reclaimed
water (WARMF)
– Under-prediction of stream temperature during spring (WARMF)
• Non-critical periods for dissolved oxygen
– Under-prediction of total nitrogen and total phosphorus
• Non-bioavailable organic nutrient component is low
8
Recap of 2011 Model Extension/Update
(continued)
• Overall Model Performance
– Results consistent with original calibration
– Model performance still acceptable for
more recent time periods
– Both models considered ready for use to
support the third-party WQS and TMDL
review efforts
• Reporting
– Documented results in Model Confirmation
Report (11/28/11)
– Presented results to stakeholders in
December 2011
9
2012/2013 Model Extension/Update
• Goal: keep models current and build confidence in
models
• Extended all databases through 12/31/2011
– Climate, diversions, point sources, air quality, reservoir operations, observed
flow, observed water quality
– QA/QC of diversion input data to ensure consistency between the watershed
and river model
• Upgraded to WARMF Version 6.5b (released 5/2012)
• Minor refinement of calibration
• WARMF: Minor soil coefficient and temperature lapse factor adjustments to
improve simulation of extreme low-flow conditions and upper watershed
snowmelt hydrology
• TRHSPF: Slight decrease in rate of organic labile N and P settling
10
Snapshot Summary of Results
• Several previous shortcomings addressed
– Improved snowmelt and low flow hydrology in upper watershed
– Reduced general under-prediction of total nitrogen
– Updated and QA/QC’d diversion data across all models
• Overall Model Performance
– Results “as good as” or “better” for 2000-2008 as
compared to prior model update
– Results within the range of uncertainty for new years
(2009-2011) - 2009 was a challenging/unusual year
– Overall, total nutrients are still slightly low
• Inorganic nutrients within range of uncertainty
• Organic nutrients slightly low
• Increasing organic nutrients will not change DO significantly
• Documented results in updated model
confirmation report
11
WARMF: Flow at Reno/Sparks
Location
Reno/Sparks
Number of
Modeled Observed
Observed
Mean
Mean
Points
496.2
498.8
4,383
r2
Relative
Error
0.89
-2.61
12
WARMF: Total Nitrogen at Reno/Sparks
Location
Reno/Sparks
North Truckee
Drain
Steamboat
Creek
Number of
Modeled Observed
Relative
Observed
Mean
Mean
Error
Points
0.35
0.42
145
-0.07
1.44
1.657
145
-0.17
1.56
1.63
145
-0.11
2009 unusual year
13
WARMF: Nitrogen Species at Reno/Sparks
14
WARMF: Total Phosphorus at Reno/Sparks
Location
Reno/Sparks
North Truckee
Drain
Steamboat Creek
Number of
Modeled Observed
Relative
Observed
Mean
Mean
Error
Points
0.03
0.03
145
0.00
0.23
0.28
0.22
0.26
172
171
0.00
0.01
15
WARMF Model Confirmation Summary
• Flow
– Extreme low-flow periods and snow melt peaks improved with minor parameter
modifications in upper watershed (above Farad)
– r2 for the Truckee River at Reno/Sparks improved slightly to 0.89 (considered “very
good”)
• Nitrogen
– Inorganic nitrogen within range of uncertainty
– Total nitrogen generally lower than observed
• Bias in observed data due to non-detects?
• Missing or underestimated organic nitrogen source?
• Phosphorus
– Annual and long-term total phosphorus and orthophosphate within range of
uncertainty
– Many observed TP values at Reno/Sparks below PQL
16
TRHSPF: Streamflow at Vista
Average Annual Streamflow
Vista
Model
1,400
Location
Vista
Near Tracy
Below Derby Dam
Wadsworth
Near Nixon
Data
Streamflow (cfs)
1,200
1,000
800
600
400
200
0
2000
2001
2002
2003
2004
2005 2006
Calendar Year
2007
2008
2009
2010
2011
r2
N
0.88
0.89
0.90
0.88
0.86
4,383
4,383
4,383
4,383
4,383
Slight improvement in
r2 from previous
model confirmation
results
17
TRHSPF: Total Nitrogen at Lockwood
Average Annual Total Nitrogen
Lockwood
Model
2.0
Data
1.8
Total Nitrogen (mg/L)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
2000
2001
2002
2003
2004
2005 2006
Calendar Year
2007
2008
2009
2010
2011
Error bars represent the 90% confidence interval of the mean.
2009 unusual year
18
TRHSPF: Total Phosphorus at Lockwood
Average Annual Total Phosphorus
Lockwood
Model
Data
0.30
Total Phosphorus (mg/L)
0.25
0.20
0.15
0.10
0.05
0.00
2000
2001
2002
2003
2004
2005 2006
Calendar Year
2007
2008
2009
2010
2011
Error bars represent the 90% confidence interval of the mean.
data anomalies?
19
TRHSPF: Dissolved Oxygen
(Tracy/Clark: 2002-2005)
20
TRHSPF: Dissolved Oxygen
(Tracy/Clark: 2006-2011)
21
TRHSPF Model Confirmation Summary
• Flow
– r2 ranges between 0.86 to 0.90 for all stations
– Rating of “very good”
• Nutrients
– Model predictions fall within range of uncertainty of observed data for
large majority of years (exception is 2009)
– Slight under-prediction of TN and TP
– Inorganic nutrients are reasonable overall
• Inorganic N within the range of uncertainty
• Ortho-P slightly over-predicted
– Organic nutrients slightly low
• Dissolved Oxygen
– Model predictions are within the range of the data
– Overall model performance is “good”
22
Review of Model Confirmation Report
• Confirmation Report available on TRIG July 23, 2013
– Email to Focus Group
– Form for written comments on confirmation report
(electronic submittal)
– Due August 16th, 2013
• Supplementary background material on TRIG
– Original calibration reports
– Presentations from previous Focus Group meetings
• TRIG – Truckee River Info Gateway:
– http://truckeeriverinfo.org
23
Overview of General Approach for
WQS Modeling
Development of Technical Rationale
Modeling Approach to Support
WQS Review
Objective: Identify appropriate site-specific nutrient
WQS that when met, would adequately meet DO
criteria given a representative flow condition
1. Identify flow condition(s)
2. Test range of instream concentrations of nitrogen and
phosphorus
3. Evaluate the extent to which the DO water quality
standard will still be met
25
Conceptual Plot of Model Results
% of time DO WQS is violated
Relationship between Nutrient
Concentrations and DO WQS Attainment
?
Possible Nutrient WQS
(Based on representative
flow condition)
26
Conceptual Plot of Model Results
% of time DO WQS is violated
10.0
Based on representative
flow condition
5.0
?
0.0
0.04
0.05
Possible Nutrient WQS
0.06
27
General Approach:
Iterative TRHSPF WQS Simulations
• Representative flow year (TROM output)
• Linked WARMF – TRHSPF simulation
– WARMF provides “baseline” loads and flows into river
– TRHSPF run iteratively with different concentrations of TN/TP/Ortho-P
• Adjust N and P loads into river (increase or
decrease) to match annual average river
concentrations to “proposed” WQS
• Locations with adjustments:
– East McCarran (upstream model boundary)
– Segments with incoming loads (North Truckee Dr., Steamboat Cr., TMWRF)
• Evaluate resulting attainment of DO WQS
28
Matrix of Scenarios Tested with 10th Percentile
and 50th Percentile Flow Regimes
Total Phosphorus and Ortho-P (mg/L)
Total Nitrogen (mg/L)
0.040
(≈ baseline)
0.075
x
0.65
0.75
0.050
x
x
0.10
(≈ baseline)
x
x
x
0.85
x
x
1.00
x
x
• Concentrations vary temporally but hit target WQS on an annual average basis
• Incoming loads are adjusted at upstream boundary (E. McCarran), North
Truckee Drain, and Steamboat to hit target WQS
29
Technical Decision Points
Technical Decision Points for Focus
Group Input
• WQ models: Review Model Confirmation Report and
confirm that model calibration is complete and satisfactory
(Jul)
• WQS modeling process
– General approach for analysis (Jul)
– Selection flow years/conditions for analysis (Aug)
– Analysis of model results (spatial aggregations, critical reach,
critical season/month) (Aug)
– Speciation of Phosphorus WQS: Ortho-P vs. TP (Aug/Sep)
– TN WQS: evaluation of both single value max and annual ave.
WQS (Aug/Sep)
• Results of WQS model runs (Aug/Oct)
• Technical Rationale for WQS revision (Oct/Jan)
31
Anticipated Schedule and Key
Milestones
Next Steps
• Focus Group comments and feedback:
– Model Confirmation Report
– Technical approach
• Working group proceeding with resolution of technical
decision points
• Continuation of preliminary WQS model runs
• Upcoming Focus Group Workshops (City of Fernley)
– Aug 28, 2013 (W): 9 AM – 12 PM
• Comments on model confirmation report due August 16
–
–
–
–
Sep 18, 2013 (W): 9 AM – 12 PM
Oct 16, 2013 (W): 9 AM – 12 PM
Jan 15, 2014 (W): 9 AM – 12 PM
Additional Stakeholder / Focus Group meetings TBD in 2014
33
NDEP Timeline
• 12/1/2013: Preliminary Draft LimnoTech report on modeling
• 1/1/2014: Review completed by Working Group
• 1/15/2014: Draft LimnoTech report on modeling results
• 2/15/2014: Review completed by Focus Group
• 3/1/2014: Final LimnoTech report on modeling results
• 4/1/2014: Draft NDEP Rationale/Petition for proposed standards changes
• 5/1/2014: NDEP Workshops – Focus Group, general public
• 6/30/2014: Final NDEP Rationale/Petition to LCB
34