Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 1

Lake Tahoe TMDLLake Tahoe TMDLPhase TwoPhase Two

Fall 2007 Public Participation Series

Source Category Group Focus Team Meetings

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 2

TMDL Program Overview

A science-based plan to restore

Lake Tahoe’s clarity

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 3

Central TMDL QuestionsQuestions Addressed1. What pollutants are causing Lake Tahoe’s clarity loss?

2. How much of each pollutant is reaching Lake Tahoe?

3. How much of each pollutant can Lake Tahoe accept and still achieve the clarity goal?

Current Questions1. What are the options for reducing pollutant inputs to Lake

Tahoe?

2. What strategy should we implement to reduce pollutant inputs to Lake Tahoe?

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 4

Source Category Group AnalysisOpportunities

• Basin-Wide load reduction estimates

• Relative load reduction opportunity among source categories

• Consistent methods to evaluate future pollutant control options

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 5

Source Category Group Analysis Boundaries

• Not suited to project scale

• Evaluated pollutant control options chosen for data availability

• Limited time, resources, and effectiveness data

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 6

Continuous Improvement

• Adaptive management process

• SNPLMA science funding opportunities

• Each group identified “next steps” and data needs

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 7

Focus Team Role

• Gain technical understanding of SCG approach

• Act as a liaison to your agency

• Provide input on preferred pollutant control options

• Suggestions for future work

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 8

Questions?

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 9

Questions Addressed

What is causing Lake Tahoe’s clarity loss?

• Suspended fine sediment

• Floating algae – fed by nutrients

• Very fine sediment (<20 microns) accounts for ~2/3 of the clarity conditions

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 10

How much of each pollutant is reaching Lake Tahoe?

Total Nitrogen Estimates: Percent Contribution per Source Category

Shoreline Erosion 0.5%

Stream Channel

Erosion 0.5%

Urban Upland 16%

Non-urban Upland 15.5%

Atmospheric Deposition

55%

Groundwater 12.5%

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 11

How much of each pollutant is reaching Lake Tahoe?

Fine Sediment Particle Number Estimates(particles less than 20 micrometers):

Percent Contribution per Source Category

Atmospheric Deposition

15%

Non-urban Upland

9%

Urban Upland 72%

Stream Channel Erosion

4% Shoreline Erosion < 1%

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 12

How much of each pollutant is reaching Lake Tahoe?

Total Phosphorus Estimates: Percent Contribution per Source Category

Non-urban Upland 26%

Stream Channel

Erosion 2%

Atmospheric Deposition

15%

Groundwater 15%

Shoreline Erosion 4% Urban Upland

38%

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 13

How much of each pollutant can Lake Tahoe accept and still achieve the clarity

goal?

• The Lake Clarity Model provides estimates of clarity response to load reductions

• Reducing fines has a greater potential to improve clarity

• Model output indicates significant reductions will be needed

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 14

What are the options for reducing pollutant inputs to Lake Tahoe?

Good Question!Good Question!

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 15

Approach to Answering Current Questions

• Identify load reduction options

• Quantify load reduction options

• Prepare Integrated Strategies

• Gather stakeholder input

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 16

Pollutant Load Reduction Opportunity Project - People

• Source Category Groups

• Technical Reviewers

• Source Category Integration Committee

• Project Team

• Focus Teams

PCO Concepts

Screening Process

Viable PCOs

PCO Grouping Process

TreatmentTiers

A

A

BC

A

BC

Settings

Extrapolation Process•GIS•Models

Step 1: PCO Evaluation Step 2: Site-Scale Analysis

Step 3: Basin-Wide Analysis

Nitrogen Reduction

Table

Sediment Reduction

Table

Phosphorus Reduction

Table

Tier 1

Tier 2

Tier 3

Load Tables

CostTables

Co

mb

ine

d R

es

ult

s

Ta

ble

s

Total 20 Year Cost Table

Capital Cost Table

O & M Cost Table

Cost-Effectiveness

Table

PCO Concepts

Screening Process

PCO Concepts

Screening Process

Viable PCOs

PCO Grouping Process

TreatmentTiers

A

A

BC

A

BC

Settings

Extrapolation Process•GIS•Models

Step 1: PCO Evaluation Step 2: Site-Scale Analysis

Step 3: Basin-Wide Analysis

Nitrogen Reduction

Table

Sediment Reduction

Table

Phosphorus Reduction

Table

Tier 1

Tier 2

Tier 3

Load Tables

CostTables

Co

mb

ine

d R

es

ult

s

Ta

ble

s

Total 20 Year Cost Table

Capital Cost Table

O & M Cost Table

Cost-Effectiveness

Table

PCO Concepts

Screening Process

PCO Concepts

Screening Process

Viable PCOs

PCO Grouping Process

TreatmentTiers

A

A

BC

A

BC

Settings

Extrapolation Process•GIS•Models

Step 1: PCO Evaluation Step 2: Site-Scale Analysis

Step 3: Basin-Wide Analysis

Nitrogen Reduction

Table

Sediment Reduction

Table

Phosphorus Reduction

Table

Tier 1

Tier 2

Tier 3

Load Tables

CostTables

Co

mb

ine

d R

es

ult

s

Ta

ble

s

Total 20 Year Cost Table

Capital Cost Table

O & M Cost Table

Cost-Effectiveness

Table

PCO Concepts

Screening Process

Sept. 10 and 11, 2007 Lake Tahoe TMDL - Phase Two 20

Development Summary

• PCO Selection and Evaluation

• Site Scale Analysis– Settings– Tiers

• Basin-wide extrapolation