Organic Carbon and Urban Sources What Do We Know

1
Organic Carbon and Urban Sources - What Do We
Know?
CBDA OC Conceptual Model Workgroup January 18,
2005
Michael Zanoli Department of Water Resources,
Division of Environmental Services, MWQI Program
2
What Do We Know About Urban OC Sources?

• Increasing Delta-wide due to high growth rates
• Difficult to monitor and
• evaluate impacts (NPS effect)
• Potential impacts depend on hydrology, time, and
  proximity to intakes (as with other sources)
• Basic metrics such as yields and reactivity
  appear comparable to current values for rivers,
  channels (Sac, SJR, Twitchell Is) ??

3
Daily NEMDC Contribution to Total Sacramento
River TOC Load July 2001 - June 2004
Number of Days TOC Load Contributions to
the Sacramento River were at or above 5, 10,
and 20 Load Contribution
_5 10 20 NEMDC 124 36 17
__________________________________________

n 1080
n 1080
4
Other OC Metrics
Yields (gC/m2/yr) NEMDC 3-6 Arcade Creek
12 (USGS 2003) Temperate zones 1-8
(Thurman) Reactivity (mmol THM/mol C) NEMDC
6 -12 (median) Twitchell Is drains, channels
2-16 (USGS) Rivers 4-16.5 (USGS)
5
Lessons Learned from an Urban Drain (2001-04)

• Natomas East Main Drainage Canal (NEMDC)
  discharge can contribute substantial TOC loads to
  Sacramento River during storm events, especially
  in late summer/initial fall storms
• Data suggest cumulative discharges from urban
  sources in high-growth areas in the Delta and
  tributaries could be significant TOC loading
  sources for DW intakes during these storm events
• With current and projected growth (60),
  potential impacts from urban runoff into the
  Delta will significantly increase within lifetime
  of CALFED program

6
What We Dont Know About Urban OC Sources (Info
Needed for Conceptual Model)
1. Data about physical and chemical processes
affecting carbon release from different land uses
in urban watersheds. 2. Knowing how changing
land and water management practices affect TOC
and DBP concentrations and loads? Source
adapted from Deverell pers. comm. 1/6/05 3.
Data on other urban sources (Stockton, Tracy,
etc.), esp tributary hydrology - e.g. SacR vs
SJR. (timing flow determines potential
impact). 4. How much of urban OC gets to DW
intakes and what fraction forms DBPs?
7
(No Transcript)
8
(No Transcript)
9
DOC Yields Sacramento River Basin

• Yield
• 1 Sacramento River at Bend Bridge
• 2 Sacramento River at Colusa
• 9 American River at Sacramento
• Yield 5-10 Mg/km2
• 6 Colusa Basin Drain
• 8 Arcade Creek
• 4 Feather River (including site 3, the Yuba
  River)
• Yield 10 Mg/km2
• 5 Sacramento Slough
• 10 Sacramento River Sites near Freeport
• Source Saleh, et al,. 2003

10
(No Transcript)
11
Error Estimation!(The Elephant on the Table)

• TOC/DOC Concentration
• - Drives yields (TOC, DOC), reactivity (DOC)
• - Real TOC/DOC value? Depends on
• Rep sampling/field Variability
• Lab error (commonly - 30 )
• Methods comb vs wet ox
• Flows
• - Stage measurements
• - Rating table
• - Sensor error
• Load Estimates

12
Implications of Global Climate Change

• More water earlier in season, increased intensity
  more runoff in shorter period.
• Salinity increase from sea level rise levee
  instability less Delta use possible?
• SacR becomes more important in future, esp if PC
  built because Delta not used for conveyance (no
  peat issues).
• Growth along I-5 and urban inputs to SacR could
  increase impacts.

13
Urban OC Load Nightmare

• Imagine 20 yrs in future a combination drought
  and storm pattern change has resulted in low
  river flows, low reservoir levels, and more water
  coming in a much shorter period.
• Freak storms from above increase
• The economy is slow less logging and
  construction so usual nps oc loads in SacR are
  lower/stable.
• But urban growth has continued, even if slowed a
  bit
• Ag drainage lower/stable because less water
  land conversion
• RESULT ?
• Urban source dominate river oc loads during many
  more storms!

14
Current Challenges

• Hard to Get Data on Loading-no Baseline
• No Regulatory Hook to Require Monitoring
• Efforts to Work With the CVRWQCB Have Been
  Disappointing
• Urban Discharge Growing

15
Assess Sources and Loads

• Monitoring Station Needs
• Location
• Parameters
• Regulatory Purposes
• Cumulative Discharges- Basin Plan
• EIR/EIS Impact Significance
• Provide Priorities for Watershed Protection
  Projects

16
Assess Sources and Loads

• Model Transport of Contaminants From Different
  Sources
• Determine Priority Sources for Watershed
  Protection Efforts
• Apply Information to Regulatory Processes or
  Control Efforts

17
Assess Sources and Loads

• Loading Information From Various Land Uses
• Determine Sampling Locations to Fill in the Gaps
• Model Development for Transport and Load at
  Intakes.

18
Future Model Uses

• Early Warning (Real Time forecasting)
• Planning Tool for Future Impacts (long term
  forecasting)
• Assess Sources and Loads
• Monitoring and station location needs
• Regulatory purposes ( TMDLs)
• Provide priorities for watershed protection
  projects
• Contamination Scenarios for Emergency Preparedness