Progress in Estimating Loads at Mallard Island

Nicole David Nicole David Lester McKeeLester McKee

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Objective

• Obtain contaminant data collected at Mallard Island

• Use concentrations in combination with sediment data to estimate loads

• Calculate long-term averages beginning with WY 1995

• Make recommendations to improve TMDLs

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MethodsMethods

1. Use SSC data from USGS from 1995 to present

2. Use instantaneous SSC and contaminant data to develop a regression relationship (WY 2002-2006)

3. Estimate 15 minute contaminant concentrations

4. Calculate daily average concentrations

5. Use linear interpolation to fill data gaps

6. Combine estimated daily concentrations with Delta Outflow to estimate daily advective loads

7. Correct loads for the effect of tidal influence and dispersion

Step by StepSSC

• Turbidity measurements taken at MI in 15 minute intervals with optical sensor (USGS)

• Data processing system utilized to erase unusual high voltage outputs of short duration

• Data converted to SSC concentrations using linear regression equation and calibrated with instantaneous samples

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SSC data for the Period of Record

0

50

100

150

200

250

Dai

ly A

vera

ged

Su

spen

ded

S

edim

ent

(mg

/L)

Measured

InterpolatedInterpolated data = 22%

1994 1998 2002 2006

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Step by StepDAYFLOW

• Discharge calculated continuously by DWR

• Input data for discharge include the principal Delta stream inflows, Delta precipitation, Delta exports, and Delta gross channel depletions

• DAYFLOW (computer program for determining Delta hydrology) accounts for advective flux only

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Dayflow for the Study Period

0

100,000

200,000

300,000

400,000

500,000

600,000

Date

Da

yfl

ow

(c

fs)

1994 1998 2002 2006

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Step by StepLoad Analysis

• Scatter plot for contaminant and SSC relationship including all data collected

SSC vs. Hg at 0 - 150,000 cfs

y = 0.11x + 2.98

R2 = 0.78

0

20

0 20 40 60 80 100 120

SSC in mg/L

Hg

in n

g/L

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Step by StepLoad Analysis

• 15 minute contaminant concentrations estimated using regression line

• DAYFLOW combined with daily SSC to estimate daily advective loads

• Tidally driven advective and dispersive fluxes estimated with velocity and SSC data (USGS)

• Freshwater advective loads adjusted with estimates for tidally driven fluxes

• Errors associated with calculation and an additional error for lab analysis are estimated

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Step by StepLoad Analysis

Date SSC 15 min Flow HgT HgT dayAv Advective Load Dispersive Load Total (mg/L) (cfs) (ng/L) (ng/L) (kg) (kg) (kg)

10/1/1996 0:00 36 4,687 8.31 9.51 0.11 -0.05 0.06

=0.11*SSC+2.98

Dayflow*3600*24*1000*HgT dayAv/1,000,000,000,000

Dispersive=-Advective*Dispersive Flux Ratio

Advective+Dispersive=Total

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Samples Collected

* Preliminary data

Water Year Hg PCBs PAHs oc-Pest PBDEs Se2002 10 10 10 10 - -2003 23 23 23 23 - -2004 31 31 31 31 - -2005 10 10 10 - 10 102006* 25 25 25 - 25 25Total 99 99 99 64 35 35

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Flows at Mallard Island and Input from Yolo Bypass in 2006

0

100,000

200,000

300,000

400,000

Dec-05 Jan-06 Feb-06 Mar-06 Apr-06 May-06

Dates

Dis

char

ge

in c

fs

Delta Out

Sac River

Yolo

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SSC – Hg Relationship

0

100,000

200,000

300,000

400,000

12

/12

1/1

2

2/1

2y = 0.11x + 2.98R2=0.74

y = 0.22x + 4.31R2=0.66

SSC vs. Hg at 0 - 150,000 cfs

y = 0.11x + 3.08

R2 = 0.78

0

20

40

60

80

0 20 40 60 80 100 120

SSC in mg/L

Hg

in n

g/L

SSC vs. Hg at 150,000 - 370,000 cfs

y = 0.22x + 4.31

R2 = 0.66

0

20

40

60

80

0 20 40 60 80 100

SSC in mg/L

Hg

in n

g/L

Low Flow Data

y = 0.12x + 2.54

R2 = 0.8

y = 0.29x - 2.13

R2 = 0.8

0

2

4

6

8

10

12

14

16

0 20 40 60 80 100 120

SSC (mg/L)

Me

rcu

ry (

ng

/L)

EC < 2 mS/cm

EC > 2 mS/cm

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Results• Revised annual mercury load for Delta

• Particles leaving Delta during high flows are more contaminated

• New load estimates for mercury about 33% higher than previously predicted

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Flows and Mercury

Dec/05 Jan/06 Feb/06 Mar/06 Apr/06 May/06 Jun/06

Flo

w in

cm

s

0

2000

4000

6000

8000

10000

12000

Delta OutflowYolo BypassSacramento River

TH

g in

ng

/L

0

10

20

30

40

50

Mercury Concentration

Loads from the Delta

* Preliminary data, still missing September

DO NOT QUOTE!

Water Year Flow (Mm^3) Sediment (Mt) Hg (kg) Hg (kg) rev % Change1995 51,559 2.58 399 599 501996 31,436 1.01 184 211 151997 42,307 2.24 351 579 651998 53,639 2.42 389 538 381999 27,805 0.84 156 163 52000 22,394 0.66 123 142 152001 8,565 0.26 52 53 22002 11,303 0.31 58 61 42003 17,330 0.55 97 101 42004 18,577 0.64 109 131 212005 18,588 0.42 81 86 62006* 50,020 - -

Average 29,460 1.08 182 242 33

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Unique contaminant datasetfrom Delta gained through January 2006 flood

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Delta Outflow from 12/20/05 to 01/25/06

0

100,000

200,000

300,000

400,000

12/20/05 12/30/05 1/9/06 1/19/06

Dates

Dis

char

ge

in c

fs

370,000 cfs

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THANK YOU

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