Mallard Island and the Largest Flood Event Since 1997

Nicole DavidLester McKeeSan Francisco Estuary Institute

Sacramento RiverFlood Control System

Shasta Dam

Hillcrest

Freeport

Yolo Bypass Schematic

Sampling Events

• December 25-28, 2005

First “Flush” sampled at Mallard Island, 9 samples + 1 duplicate

• January 2-18, 2006

Contingency Budget used for 14 samples + 1 duplicate for flood event

Data from 12/30/2005 through 01/18/2006   ·   Duration: 19 days

Sacramento River at Freeport

88,000 cfs

Data from 12/30/2005 through 01/18/2006   ·   Duration: 19 days

Yolo Bypass near Woodland

260,000cfs

Yolo Bypass

Cache Creek

Sacramento River

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

370,000 cfs

Cross Section SurveyTuesday, January 10, 2006

Morning

Afternoon

USGS performed 8 cross-sectional surveys of velocity and turbidity

Results similar to previous surveys, establishing MI gauge house as representative sampling site

Cross Section Surveys

Return Frequency

Storm Event Comparison

Precipitation over 24 hour period

Hillcrest Shasta Dam Yolo Bypass Peak

inches inches cfs December 29,2005 1.76 0.96 December 30, 2005 0.56 1.00 December 31, 2005 5.16 2.76 January 1, 2006 0.84 0.68 January 2, 2006 2.16 2.56 January 3, 2006 0.28 0.16 Total 10.76 8.12 260,000 March 3, 2006 0.12 0.40 March 4, 2006 0.56 0.32 March 5, 2006 0.20 0.20 March 6, 2006 3.08 4.44 March 7, 2006 1.84 0.96 March 8, 2006 0.64 0.08 Total 6.44 6.40 70,000

Yolo Bypass March 1-12, 2006

Relationship between total Hg and SSC influenced by salinity

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

Salinity Measurements in Dec 05 and Jan 06

Sample ID Date Value in ppt EC in mS/cmMI 300 25-Dec-05 0.3 0.7MI 300 Dup 25-Dec-05 0.3 0.7MI 301 26-Dec-05 0.8 1.9MI 302 26-Dec-05 0.3 0.7MI 303 26-Dec-05 0.3 0.7MI 304 27-Dec-05 0.2 0.5MI 305 27-Dec-05 0.2 0.5MI 306 27-Dec-05 0.3 0.9MI 307 28-Dec-05 0.2 0.5MI 308 28-Dec-05 0.3 0.6MI 309 2-Jan-06 0.1 0.2MI 310 4-Jan-06 0.1 0.2MI 311 5-Jan-06 0.1 0.2MI 311 Dup 5-Jan-06 0.1 0.2MI 312 5-Jan-06 0.1 0.2MI 313 6-Jan-06 0.1 0.2MI 314 6-Jan-06 0.1 0.2MI 315 7-Jan-06 0.1 0.2MI 316 8-Jan-06 0.1 0.2MI 317 10-Jan-06 0.1 0.2MI 318 10-Jan-06 0.1 0.2MI 319 12-Jan-06 0.1 0.2MI 320 14-Jan-06 0.1 0.2MI 321 16-Jan-06 0.1 0.2MI 322 18-Jan-06 0.1 0.2

Seth Shonkoff,SFEI

Max Delaney, SFEI

Jay Davis, SFEI

Richard Looker,Regional Board

Jennifer Hunt,SFEI

Thank You!