Der Ausblick von der Flussmündung Hinauf zu den

Bergen

Herr Doctor Khalil E. Abu-Saba

The View from DownstreamKhalil Abu-Saba

San Francisco Bay Regional Water Quality Control Board

Manage in the watersheds.

Measure in the water.

Overview

• What chromium and silica taught us

• The mercury story in California

Connecting downstream data

to upstream watersheds:

The usual caveats...

• This discussion is about:

• Published historic accounts

• Public information (hearings, staff reports, peer-reviewed science)

• Staff recommended actions

• This discussion is not about:

• The will or intent of the Regional Board, the State Board, or the State of California

• The anticipated outcome of any public process

Apr

. '92

Mar

. '93

May

'93

Sep

. '93

Feb

. '94

Apr

. '94

Aug

. '94

Feb

. '95

Apr

. '95

Aug

. '95

Feb

. '96

Flo

w (

m3

S-1

)

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Sacramento RiverYolo Bypass

Hydrology + Geography = Geochemistry

[Cr(

III)

+ C

r(V

I)]

(n

M)

12345678

Time8/30/939/13/939/23/93

Flo

w (

m3S

-1)

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1000

2000

3000Salinity

0 10 20 30

[Si]

(µ

M)

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200

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[Cr(

III)

+ C

r(V

I)]

(n

M)

0

10

20

30

Salinity0 10 20 30

[Si]

(µ

M)

80

120

160

Time

2/14/932/24/933/5/93

Flo

w (

m3S

-1)

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Sacramento R.

Yolo Bypass

Summer: Low Flow Winter: High Flow

Chromium

Silica

Flow

Details in Abu-Saba and Flegal (1997)

First Point: The View from Downstream

• Chromium and Silica are geochemical tracers• We can see the effect of shifting freshwater sources

downstream• Winter 1993 pulses of waters entered estuary• Chromium / Aluminum ratios also showed a shifting sediment

source in Winter 1993

Second Point: The View from Downstream

• The story of mercury in California is recorded in the sediments

Sand Clay

Mercury in Sediment

Current Background

Sources

Historic Baseline

RMP Base Program Data

0.0

0.4

0.8

1.2

0 50 100

% Fines (<63 µm) ClaySand

Mercury (ppm)

Design Integration Workgroup

Current Background

0.0

0.4

0.8

1.2

0 50 100

% Fines (<63 µm) ClaySand

Mercury (ppm)

State TMDL funds to evaluate Pre-human condition of Lower South Bay

Current = 0.40

Baseline = 0.060.0

0.4

0.8

1.2

0 50 100

% Fines (<63 µm) ClaySand

Mercury (ppm)

Guadalupe River Mercury TMDL Spearheaded by SCVWD

New Almaden

0.0

0.4

0.8

1.2

0 50 100

% Fines (<63 µm) ClaySand

Mercury (ppm)

RMP Air Deposition Study and relevance to contemporary background

0.34 ppm

?

?

Mining

Air Dep.

Regional

Global

0.0

0.4

0.8

1.2

0 50 100

% Fines (<63 µm) ClaySand

Mercury (ppm)

0.0

0.4

0.8

1.2

0 50 100

% Fines (<63 µm)

Mercury in Bottom

Sediments(µg/g)

ClaySand

Investigation of remote watershed sources:

Winter 1993

CALFEDCVRWQCBUCSC

15

Bacteria in wetlands, mudflats and sloughs

Total Mercury

Methylmercury

Methylation Bioaccumulation

• Mercury is methylated in the margins of the Bay

• Methylation rates highest at the fresh-salt interfaces

• High total mercury concentrations ALWAYS associated with high methylmercury concentrations

• High methylmercury concentrations OFTEN, but NOT ALWAYS associated with high total mercury concentrations

Link to Beneficial Uses:Methylmercury studies by CALFED, BASMAA, SCVWD,UCSC

Basin Plan Narrative Objective for Bioaccumulation

• “Controllable water quality factors shall not cause a detrimental increase in the concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.”

Third Point: The View from Downstream

• RMP Base Program sets the stage• Pilot, special, and external studies address key

uncertainties• Today’s talk:

– SFEI, State, CALFED, BASMAA, SCVWD, CVRWQCB, UCSC….

• Many many others– POTW ultra-clean monitoring, near-field methylmercury

measurements, SFEI consumption study, RMP fish surveys...

• Keep those cards and letters coming!

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But What Does it All Mean?