1

MERCURY OFFSET FEASIBILITY STUDY FOR THE

SACRAMENTO RIVER WATERSHED

Vicki Fry, P.E. Sacramento Regional County Sanitation District

Stephen McCord, Ph.D., P.E. Larry Walker Associates

October 5th, 2004 WEFTEC®2004 New Orleans, Louisiana

Active Stakeholders:

Federal & State Regulators Public Land Managers Scientists NPDES Permittees Industry Representatives

SRCSD Board of Directors Mercury Offset Consultant Team

Acknowledgements

2

Overview

!  Regulatory Framework

!  Environmental Context

! Approach to Offset Feasibility

Sacramento Regional Wastewater Treatment Plant (SRWTP)

3

SRWTP’s THg cap is 5.1 lbs/year

0 1 2 3 4 5 6 7 8

Years

Poun

ds p

er y

ear

2004

BANK OFFSET Projected Load

Cap

Work Plan for Reducing Pollutant Loads to the Sacramento River – Mercury

! Source Control

! Additional Treatment

! Offset Feasibility Study

Pilot under EPA Pollutant Trading Policy

SRWTP August 2000 NPDES Permit

4

Overview

!  Regulatory Framework

!  Environmental Context

!  Approach to Offset Feasibility

Sacramento River Watershed

5

Yolo Bypass(48%)

SacramentoRiver atVeterans

Bridge(49%)

SRWTP(.32%)

AmericanRiver (2.4%)

Relative Mercury Loads to the Delta from Sacramento R. 1993 - 1998

Natural Sources

6

Natural & Legacy Sources

Natural & Legacy Sources

7

Hydraulic monitors in operation, North Bloomfield mine, circa 1880s, Malakoff Diggings, Nevada County

Hydraulic mine, ground sluice system, circa 1870s, Scott Valley mine, Siskiyou County

8

Section 303(d) of the Clean Water Act

Mercury-Impaired

Water Bodies

Fish Advisories

9

TMDLs

Overview

!  Regulatory Framework

!  Environmental Context

!  Approach to Offset Feasibility

10

Feasibility Study Approach

! Identify mercury sources

! Quantify source loads

! Identify and address site-specific issues

Transport to Water Transport & Transformations

Bioa

ccum

ulat

ion

&

Biom

agni

ficat

ion

Exposure

Connecting Mercury in the Environment to Fish

Multiple mercury sources

Mercury in Water & Sediments

Methylmercury in water and sediments

Fish Tissue

Consumers

1

2

3

4

5

11

Source Control

! Clean up contaminated mine sites

! Treat spring waters ! Control erosion

Transport Control

! Settling basin

! Dredge hotspot sediments

Accumulated Sediment

Storage Pool Inflow

Outflow

12

Break the Chain

! Oxygenate a reservoir

! Manipulate food web

! Reduce fish consumption

Hg MeHg

Hg MeHg X X

X

X X

Dominant Selection Criteria

! Sources – Where is it coming from?

! State of the Science – Can we control it?

! Data Availability – How much is enough?

13

Offset Ratios Account for differences between

point of discharge and offset project loads

Credit = Load Reduction

x Uncertainty

x Location

x Bioavailability

Next Steps

! Legal issues

! Coordinate under TMDLs

and NPDES permit

! Bioavailability study

14

Is Discharge Creating a Hotspot?

! Water Quality Monitoring

! Clam Monitoring

What is the Relative Bioavailability of Mercury Sources?

Methyl Mercury

Inorganic Mercury

Reactive - Aqueous

Inert - Rock

Available - Sorbed

15

SUMMARY

•  Stakeholder Process •  Regulatory Framework •  Environmental Legacy •  Defining Feasibility

Questions?

16

Section 303(d) List of Mercury-Impaired Water Bodies