Comparative Analysis of Loads of Mercury in Coyote Creek and

Guadalupe River

Lester McKee

RMP SPLWG Chair

San Francisco Estuary Institute

lester@sfei.org

Acknowledgements and Data Sources

Coyote Creek• USGS discharge

– WY 1999 – 2006 (ongoing)

• USGS suspended sediment– WY 2005– WY 2006

• Regional Board TMDL laboratory funding ($10k)

– WY 2005 PCB, PBDE, HgT, SSC, organic carbon

• Data– SFEI field team able to grab 7

samples during wading stage only during breaks from Guadalupe R. sampling

Guadalupe River• USGS discharge

– WY 1929 – 2006 (ongoing)

• USGS/SFEI suspended sediment– WY 2003 – 2006 (ongoing)

• Funding – WY 2003 CEP– WY 2004 CEP / RMP– WY 2005 RMP / SCVWD / USACE /

SCVURPPP• Data

– HgT, HgD, MeHgT, MeHgD, Bedload HgT

Land Use Comparisons

Area(below Dams) Industrial Commercial Residential

Open/Agricultural

Coyote Ck. (km2) 335 15 16 83 222

Percentage (%) 100 4 5 25 66

Guadalupe R. (km2) 236 30 30 137 38

Percentage (%) 100 13 13 58 16

Field LocationsCoyote Ck. at Hwy 237

USGS 11172175Area: 826 km2

Guadalupe R. at Hwy 101USGS 11169026

Area: 414 km2

Guadalupe R.Coyote Ck.

Methods

Sampling Location

USGS Gage Shelter

Results – Coyote Creek

Sample Number Date / time

Suspended Sediment

(mg/L)

Total Mercury (ng/L)

CC40 12/7/04 9:05 - 40

CC70 12/27/04 12:22 51 11

CC80 12/31/04 14:51 228 54

CC90 1/7/05 8:38 77 21

CC91 1/7/05 16:35 110 39

CC92 1/9/05 11:55 70 18

CC100 1/11/05 17:04 338 59

CC100 Dup 1/11/05 17:06 335 57

Total Mercury v Suspended Sediment(All data)

y = 0.21x

R2 = 0.75

0

10

20

30

40

50

60

70

0 100 200 300 400

Suspended Sediment (mg/L)

Tot

al M

ercu

ry (

ng/L

)

Total Mercury v Suspended Sediment(Runoff from Upper and Lower Watershed)

y = 0.19x

R2 = 0.84

y = 0.32x

R2 = 0.87

0

10

20

30

40

50

60

70

0 100 200 300 400

Suspended Sediment (mg/L)

Tot

al M

ercu

ry (

ng/L

)

Lower

Upper

Loads Calculation Methods(WY 2005)

• USGS 15 minute discharge

• USGS 15 minute SSC estimates from GCLASS based on rating relationships between flow and about 100 real measurements of SSC

• Regression between instantaneous SSC and Total Mercury concentrations– All data

– Separate regressions for water derived from Lower and Upper watershed

Maximum Daily and Flood LoadsTotal Mercury

Wet Season (Oct 2004 - Apr 2005) (kg) 2.5

Maximum Daily (2/15/05)

Load (kg) 0.23

Load (% wet season) 9

Largest Flood (2/15/05 14:30)

Load (kg) 0.28

Load (% wet season) 12

Why so little during the largest flood?

0

200

400

600

800

1000

1200

Oct-04 Nov-04 Dec-04 Jan-05 Feb-05 Mar-05 Apr-05

Date

Flo

w (

cfs)

Results – Monthly Loads

  2004     2005        

  Oct Nov Dec Jan Feb Mar Apr Total

Flow (Mm3) 3.3 1.3 4.9 6.9 10.3 13.1 7.5 47

Total Mercury (kg) 0.4 0.02 0.5 0.2 0.7 0.6 0.1 2.5

Estimated Average - Methods

0

50

100

150

200

19

71

19

73

19

75

19

77

19

79

19

81

19

83

19

85

19

87

19

89

19

91

19

93

19

95

19

97

19

99

20

01

20

03

20

05

Water Year

Flo

w (

Mm

3 )

y = 0.7211x

R2 = 0.9206

0

100

200

300

400

500

600

0 200 400 600 800

Guadalupe R. at Hwy 101 (cfs)

Co

yote

Ck.

at H

wy

23

7 (

cfs)

Average = 41 Mm3

MeasuredEstimated

Estimated Average Coyote Loads

• Using the range in flow experienced from WY 1971 to WY 2006 we estimate the following:

  Flow (Mm3)

Total Mercury(Estimated using

separate regressions)(kg)

Total Mercury(Estimated using

A single regression)(kg)

Minimum 2.0 0.001 0.001

Maximum 173.9 55 44

Average 40.6 7 6

Coyote Creek versus Guadalupe RiverCoyote Creek

HgT(ng/L)

HgT(mg/kg)

Load(kg)

Export(µg/m2/yr)

11-58 0.17-0.367

(0.001 - 55) 20

Guadalupe River

HgT(ng/L)

HgT(mg/kg)

Load(kg)

Export(µg/m2/yr)

DL - 18,673 0.41 - 95140

(0.03 - 1,000) 600

Particle ConcentrationsCoyote Ck, Guadalupe R. and Sacramento R.

1

10

100

1,000

10,000

10 100 1000

Suspended Sediment (mg/L)

To

tal M

ercu

ry (

ng

/L)

Guadalupe River at Highway 101 (Mining water)

Guadalupe River at Highway 101 (Urban water)

Coyote Creek at Highway 237 (Urban water)

Sacramento River at Mallard Island (Floods >150,000 cfs)

Coyote Creek at Highway 237 (Non-urban water)

Sacramento River at Mallard Island (Floods <150,000 cfs)

Applicable Management Questions

B. Loads of mercury and methylmercury

• Are current estimates about loading to San Francisco Bay from watersheds, wastewater treatment facilities, and atmosphere valid?

• What is the contribution of atmospheric deposition to urban storm water?

Applicable Management Questions

C. Processes of mercury methylation

• What is the relative bioavailability of mercury entering the Bay from various loading sources (e.g., wastewater treatment facilities, atmosphere, urban runoff, tributaries, newly eroded historic sediments, etc)?

Applicable Management Questions

D. Given what we currently understand about processes, loads, and impacts (Sections A, B, and C), what are the management implications?

• Given that rivers, creeks, and storm drains discharge methyl mercury, what can be done to manage production in the watershed and urban environments, and to manage downstream impacts as it passes through wetlands to the Bay margin and Bay?