Focus Group Meeting: July 17, 2013

Truckee River Water Quality Standards Review

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

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Model Linkage for Truckee River WQS Analysis

WARMF

TRHSPF

TROM

Reservoir Releases, Diversions

Diversions Tributary Flows, Nonpoint Sources

In-stream Water Quality

Demands, Water Operations, In-stream Flow Targets Meteorology, Land Use, TMWRF

Effluent and Re-use

TMWRF Effluent

WARMF: Watershed Model

• 125 catchments (subwatersheds)

• Time step = 1 day

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• Peer reviewed, public domain

• Predicts watershed flow and pollutant loads based on– land use– meteorological conditions– water management– watershed improvements

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

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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

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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

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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

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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

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WARMF: Flow at Reno/Sparks

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Location Modeled Mean

Observed Mean

Number of Observed

Pointsr2 Relative

Error

Reno/Sparks 496.2 498.8 4,383 0.89 -2.61

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WARMF: Total Nitrogen at Reno/Sparks

Location Modeled Mean

Observed Mean

Number of Observed

Points

Relative Error

Reno/Sparks 0.35 0.42 145 -0.07North Truckee

Drain 1.44 1.657 145 -0.17

Steamboat Creek 1.56 1.63 145 -0.11

2009 unusual year

WARMF: Nitrogen Species at Reno/Sparks

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WARMF: Total Phosphorus at Reno/Sparks

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Location Modeled Mean

Observed Mean

Number of Observed

Points

Relative Error

Reno/Sparks 0.03 0.03 145 0.00North Truckee

Drain 0.23 0.22 172 0.00Steamboat Creek 0.28 0.26 171 0.01

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

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0

200

400

600

800

1,000

1,200

1,400

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Stre

amflo

w (c

fs)

Calendar Year

Average Annual StreamflowVista

Model Data

TRHSPF: Streamflow at Vista

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Location r2 N

Vista 0.88 4,383Near Tracy 0.89 4,383Below Derby Dam 0.90 4,383Wadsworth 0.88 4,383Near Nixon 0.86 4,383

Slight improvement in r2 from previous model confirmation

results

TRHSPF: Total Nitrogen at Lockwood

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0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Tota

l Nitr

ogen

(mg/

L)

Calendar Year

Average Annual Total NitrogenLockwood

Model Data

Error bars represent the 90% confidence interval of the mean.

2009 unusual year

TRHSPF: Total Phosphorus at Lockwood

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0.00

0.05

0.10

0.15

0.20

0.25

0.30

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Tota

l Pho

spho

rus

(mg/

L)

Calendar Year

Average Annual Total PhosphorusLockwood

Model Data

Error bars represent the 90% confidence interval of the mean.

data anomalies?

TRHSPF: Dissolved Oxygen(Tracy/Clark: 2002-2005)

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TRHSPF: Dissolved Oxygen(Tracy/Clark: 2006-2011)

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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”

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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

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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

phosphorus3. Evaluate the extent to which the DO water quality

standard will still be met

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Conceptual Plot of Model Results

Possible Nutrient WQS

% o

f tim

e D

O W

QS

is v

iola

ted

(Based on representative flow condition)

Relationship between Nutrient Concentrations and DO WQS Attainment

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Conceptual Plot of Model Results

Possible Nutrient WQS 0.04

0.06

0.05

% o

f tim

e D

O W

QS

is v

iola

ted

0.0

5.0

10.0

Based on representative flow condition

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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 WQS28

Matrix of Scenarios Tested with 10th Percentile and 50th Percentile Flow Regimes

Total Phosphorus and Ortho-P (mg/L)

0.040 0.050 0.075 0.10

(≈ baseline)

Total Nitroge

n (mg/L)

0.65 x x0.75

(≈ baseline) x 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 WQS29

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)

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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

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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

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