Watershed Monitoring and Watershed Monitoring and Modeling in Switzer, Chollas, Modeling in Switzer, Chollas, and Paleta Creek Watershedsand Paleta Creek Watersheds

Kenneth SchiffKenneth Schiff

Southern California Coastal Water Research ProjectSouthern California Coastal Water Research Project

www.sccwrp.orgwww.sccwrp.org

Prelude to Today’s AgendaPrelude to Today’s Agenda

• Total Maximum Daily Loads (TMDLs) always benefit from more information

• Today’s presentation is mostly conceptual- many of the details have not been finalized

• Local stakeholders have extensive knowledge/experience- SCCWRP has been instrumental in bringing unbiased technical information to

TMDL development

• One goal of today’s meeting is to identify potential partnerships and collaborations

Agenda For TodayAgenda For Today

• Background

• Goals of the project

• General approach- important considerations

• Next steps

BackgroundBackground

• Sediments at the mouth of several urban creeks draining to SD Bay are listed as impaired

- chemistry, toxicity, benthic community

• Additional studies have focused the magnitude and extent of these impairments

- Chollas, Paleta, and Switzer Creeks

• TMDL development for the contaminated sediments at these creek mouths would benefit from additional data

- source analysis

- linkage analysis

Aquatic Life Weight of Evidence ResultsChollas Study Site

C01

C02

C03

C04

C05

C06

C07

C08

C09

C10

C11C12 C13 C14

Unlikely Possible Likely

Toxicity

Low Moderate High

Constituents of Potential ConcernConstituents of Potential Concern

• Trace metals- copper, lead, zinc

• Trace organics- chlordanes, PAHs, DDTs/PCBs

• Associated constituents- organic carbon, suspended solids, hardness

Study ObjectivesStudy Objectives

• What are the concentrations and loads of contaminants of potential concern?

- can we differentiate among different sources?

• What is the fate of the contaminants of potential concern?

General ApproachGeneral Approach

• Utilize empirical data to estimate sources and loads of CoPC to affected areas at the mouth of Chollas, Paleta, and Switzer Creeks

• Employ watershed models to supplement information on sources and loads of CoPC

• Link to estuary models to help ascertain fates of CoPC inputs

Use of Empirical DataUse of Empirical Data

• Want to examine multiple potential sources- urban watersheds and atmospheric deposition have been prioritized

• Watershed inputs- Focus on wet weather

• Use existing data wherever possible- MS4, Industrial, special studies

• Collect new data as needed- chlorinated hydrocarbons

Generalized Approach for Generalized Approach for Atmospheric DepositionAtmospheric Deposition

• The possibility of inputs from atm dep is high- urban air quality, localized sources

• There are two methods for estimating deposition- surrogate surfaces

- atmospheric concentrations and estimated deposition velocities

• Focus will be direct deposition onto the water surface of affected areas

- deposition onto the watershed would be an interesting component

The Use of Watershed ModelsThe Use of Watershed Models

• Watershed models can be useful TMDL tools

• Predict concentrations and loads from unmonitored storms or areas

- critical conditions

- margin of safety

• Use to define source area contributions- subwatersheds, land uses, municipal boundaries, etc.

• Predict the effectiveness of future management actions- cost efficiency of potential implementation plans

OverlandFlow

InterceptionStorage

Infiltration

Interflow

UpperZone

Storage

InterceptionStorage

Lower Zone Storage

Groundwater Storage

Deep Groundwater

Evapotranspiration

Active Groundwater Flow

Approach to Building a Approach to Building a Watershed ModelWatershed Model

• Physical data is needed for the model domain- watershed delineation, stream properties, land use, etc.

• Calibrate flow and water quality at small homogeneous land uses

• Validate flow and water quality at the end of the watershed cumulative of all land uses

Special Considerations for Special Considerations for Watershed ModelingWatershed Modeling

• There are a number of different models available- static, dynamic

• We will use a dynamic model with short time steps- one minute to one hour intervals

• Shorter time steps enable predictions of within-storm management scenarios

- first flush, peak flows, flow duration

Data Collection Strategy for Data Collection Strategy for Wet WeatherWet Weather

• Use previously collected data for land use information- requires certain assumptions

• Collect validation data at the end of each watershed- requires local data for validation

• Dynamic models necessitates dynamic water quality information

- requires multiple samples across the hydrograph

Land use sites < 0.5" 0.5" - 1.0" > 1.0" Total No.

Agriculture 3 1 1 5

Commercial 4 1 5

High density residential 4 2 1 7

Industrial 5 1 1 7

Low density residential 2 1 3

Open space 2 2

Recreational 1 1 2

Transportation 1 1 2

Natural loadings 4 11 15

33 land usesite events

30 naturalsite events

Through 4/30/05

Sample Size For Land Use-Based PollutographsRainfall Quantity

Ag

Mix

ed

Ag

Mix

ed

Ag

Mix

ed

Ag

Mix

ed

Co

mm

Co

mm

Co

mm

HD

R M

ixe

d

HD

R M

ixe

d

HD

R P

et

HD

R P

et

Ind

Mix

ed

Ind

Mix

ed

LD

R S

ew

er

LD

R S

ew

er

LD

R S

ew

er

LD

R U

nse

we

red

Op

en

Sp

ace

Op

en

Sp

ace

Co

pp

er

(kg)

0.1

1

10

100

1000

10000MeasuredModeled

Land Use Calibrations

Linking Watershed and Linking Watershed and Estuary ModelsEstuary Models

• Estuary models can make predictions about hydrodynamic and particle transport

• How much of the watershed inputs deposit in the estuary?

• Ultimately, at a specific location in the estuary, where did the sediment contamination come from?

Special Considerations for Special Considerations for Estuary Models Estuary Models

• Two-way (tidal) flow

• Hydrodynamic stratification

• Particle dynamics- flocculation, settling, dispersal, mixing

• Chemical partitioning - dissolution, precipitation

• Sediment dynamics - flux, resuspension

Approach To Building An Approach To Building An Estuary ModelEstuary Model

• Start easy and work towards the more complex- Dry weather, then wet weather

• Calibration cruises- Hydrodynamic, particle, water quality, sediment quality data

• Special studies for rate constants- Fluorescent dyes, sediment flux, particle size distributions

• Validation cruises- Try to predict measured conditions based on calibration exercise

SummarizingSummarizing

• What are the sources and loads of contaminants of potential concern?

- empirical measurements

- watershed modeling

• What is the fate of the contaminants of potential concern?

- estuary modeling

Immediate Next StepsImmediate Next Steps

• Need to prepare for wet weather sampling- Site and storm selection

- Equipment prep and encroachment permits

• Compilation of existing watershed data- physical, flow, and water quality data

• Local partners?- Leverage existing monitoring

- SCCWRP adapt to existing/planned studies

- Incorporate tools or services developed by others

Longer Term PlanningLonger Term Planning

• Determine success of watershed modeling- Requires more data?

- Model application runs

• Begin preparations for estuary modeling- Hydrodynamic and water quality?

- Primary special studies needed?

• Ability to interface with other agencies

Approach To Building An Approach To Building An Estuary ModelEstuary Model

• Physical data- geometry, bathymetry, substrate

• Hydrodynamic data- Tidal and creek forcing, thermal and density stratification, velocity

• Particle dynamics- Grain size, settling velocity, sediment resuspension

• Water quality dynamics- Dissolved/particulate phases,

-

Aquatic Life WOE ResultsPaleta Study Site

Unlikely Possible Likely

PO1

PO2

PO3

PO4

PO5

PO6

PO7

PO8

PO9

P10

P11

P12

P13

P14

P15

P16

P17

Toxicity

Low Moderate High

Phase I Measure Spatial Extent and Magnitude of Sediment Impacts

Measure sediment quality indicators at many stations: Sediment contamination Sediment toxicity Bioaccumulation Benthic community Identify and map areas of impaired or potentially impaired beneficial uses: Aquatic life Human health (screening) Wildlife (screening)

Phase II (TMDL Actions)

Determine cause of impairment Sediment/Water TIE Additional sediment/tissue chemistry

Document key indicators of impact

Temporal study of toxicity and benthic community impacts

Determine sources

Spatial analysis of data Historical data review Watershed/facility sampling

Phase III (Cleanup Actions) Identify indicator chemicals

Calculate aquatic life cleanup levels Porewater chemistry/toxicity Derive cleanup levels using AET,

EqP, or other methods Calculate human health cleanup levels

Resident seafood tissue analysis Risk modeling

Calculate wildlife cleanup levels

Resident animal tissue analysis Risk modeling

Determine cleanup boundaries Core sampling

TMDL Implementation Implement Source Control Verify Source Reduction

Cleanup Implementation Evaluate remedial options for site cleanup Implement Cleanup Actions