Lake Mead

Southern Nevada Water Authority

Quagga Mussels in Southern Nevada

David Johnson, Treatment Manager Southern Nevada Water System

July 15, 2008

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The Southern Nevada Water Authority is a regional water agency that provides drinking water to 2 million people and 40 million annual visitors.

The SNWA operates two treatment plants with a combined production capacity of 900 MGD.


Lake Mead

North Las

Vegas

Las Vegas Valley Water District

Henderson

Boulder City

Nellis

Intake 1Intake 2

AMSWTF

RMWTF

North

South

Southern Nevada Water Authority System

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The SNWA’s raw water infrastructure, which is susceptible to quagga infestation, includes:

- Five Pumping Stations - 20 Miles of Tunnels and Pipelines- Pressure and Instrument Sensing Line- Surge Systems- Pump Motors- Cooling Systems

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Control Gate

IPS-3

Forebay

Interconnection

IPS-1

Lake Mead

IPS-2

Boulder

Harbor

Saddle Island

Forebay

Forebay

Existing Intake FeaturesProposed Intake No. 3 Features

To RMWTF

To AMSWTF

To AMSWTFSaddle Island

Control Gate

June 2006 Preliminary Concepts

~ 3 miles

North

860 ft

1000 ft

1000 ft

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Risk Analysis by RNT Consulting

Variable IPS-1 IPS-2 Risk Potential

Alkalinity total mgCaCO3/L 136.8 136.5 Intense

Calcium mg/L 80.3 74.8 Intense

Chlorophyll a ug/L 1.4 <1.4No

infestation

pH 8 8 Moderate

Dissolved Oxygen mg/L 7 - 8 7 - 8 Moderate

Summer Temperature deg C 17 15 Moderate

Total Phosphorus ug/L 6.1 2.9 Little to None

Overall Likelyhood of supporting mussels Moderate

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Lake Mead’s warm temperatures allow quaggas to multiply far more quickly than in the Great Lakes.

- Veligers (free floating) into treatment plant• Maximum – 98 Billion/Day• Average – 22 Billion/Day

- Attached mussels near intake• 137,000/m2

Without intervention, quaggas could decimate Southern Nevada’s drinking water infrastructure.

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Raw Water Veliger Counts - IPS-1 and IPS-2

0

20

40

60

80

100

120

Jan2007

Feb2007

Mar2007

April2007

May2007

June2007

July2007

Aug2007

Sep2007

Oct2007

Nov2007

Dec2007

Jan2008

Feb2008

Mar2008

April2008

May2008

date

#v

elig

ers

/L

RMWTF - IPS2

AMSWTF Raw

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Chlorine is effective at controlling quagga mussels.

- However, it may not be a viable long-term solution because of:

• Safe Drinking Water Act regulations related to chlorination byproducts

• Equipment limitations and maintenance

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Additional measures currently being taken by the SNWA include:

- Installation of new chemical injection points

- Evaluation of alternative control strategies

- Installation of control strategies at new intake and pump station

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Both temporary and permanent quagga management strategies have significant financial ramifications.

- Temporary Measures• Capital - $5 Million

- Permanent Measures• Capital - $24 Million

- Annual O&M - $1 to 4 Million

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Research Needs Workshop

Sponsored by Awwa Research Foundation, Metropolitan Water District of Southern California, and SNWA

Thirty-two invited guests developed research needs – 14 experts and 18 agencies

Three research topics- Chemical Inactivation and Barriers- Population Management- Standard Methods – QA/QC

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Research Needs Identified – Chemical Inactivation and Barriers

Determination of Viability in Quagga Mussel Veligers and Assessments of Chemical Treatment Efficacy

Hydraulic Effects on Veliger Mortality in Engineered Systems

Quagga Mussel Vulnerability Assessment and Response Management Tool Development

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Research Needs Identified – Chemical Inactivation and Barriers

Demonstrate Alternative, Non-Chemical Control Technologies for Quagga Mussels for Deployment at Water Treatment Facilities

Molluscicides and Biocides for Control of Dreissenid Mussels in Water Resources

Coatings and Materials for Control of Dreissenid Mussel Attachment in Water Resource Projects

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Research Needs Identified – Population Management

Response of Quagga Mussel Veligers to Limnological Variables

Application of Biological Agents to Control Quagga Mussels

Applying Knowledge of System Ecology as a Control Strategy

Quantitative Tools for Management of Mussels in the Colorado River System

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Research Needs Identified – Population Management

Quantitative Evaluation of Quagga Mussel Outreach and Education Activities

Shifts from Planktonic to Benthic Regimes in Response to Quagga Mussel Invasion

Early Detection Methodology and Rapid Assessment Protocols for Quagga Mussels

Impact of Quagga Mussel Invasion on the Quality of Domestic Water

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Research Needs – Standard Methods QA/QC

Decision to work with Standard Methods to develop methods to be published in “Standard Methods for the Examination of Water and Wastewater”

- Enumeration• Adults• Veligers

- Sampling • Adults• Veligers

- Early Warning • Substrate samplers• Polymerase Chain Reaction (PCR)

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The Southern Nevada Water Authority and Metropolitan Water District of Southern California on May 15 and June 24, 2008 urged Congress to:

- Invest in research related to effective quagga eradication or management methods ($20 Million)

- Lead and coordinate efforts by stakeholder agencies

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Questions?

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Expert Presentations

1. Quagga Mussels in the West2. Optimizing Chemical Disinfection for

Dreissenid Mussels3. Control of Dreissenid Mussels by Chemical

Oxidants4. Freshwater Bivalve Infestations: Risks to

Assets and Available Control Options5. Dreissenid Mussel Control for Large Flow,

Once Through Systems6. Dreissena’s in Warm Water7. Threat of Dreissenid Mussels to

Reclamation Water Systems

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Expert Presentations

8. Quagga and Zebra Mussels: Patterns of Reproduction

9. Invasive Mussel Tracking and Monitoring in Lakes

10.Quagga Mussel Population Behavior11.Role of Modeling in Assessment and

Management of Quagga Mussels12.Winter Lake Drawdown as a Strategy for

Zebra Mussel Control: Results of Pilot Studies in Minnesota and Pennsylvania

13. Dreissenid Mussels in Riverine Ecosystems

Lake Mead

Documents

Transcript of Lake Mead