DeepWater Desal

Intake Assessment

1. Assessment Background and

Objectives

2. Methods Used in Assessment

3. Key Findings

4. Assessment Summary

Joe Phelan, PhD. jphelan@tenera.com

John Steinbeck jsteinbeck@tenera.com

Tenera Environmental

San Luis Obispo, CA

www.tenera.com

19 slides

Study Objectives

• Objective 1: Describe the

magnitude of the

entrainment effect.

• Objective 2: Describe the

implications of the deep

intake design in light of

entrainment effects. Blue rockfish (Sebastes mystinus) from Moser, H. G. (ed.). 1996.

The early stages of fishes in the California Current region.

1. Assessment Background and Objectives 2/19

In a Nutshell

1. Assessment Background and Objectives 3/19

• The desalination intake

pipe will entrain seawater.

• The seawater contains

living organisms.

• Those organisms are also

entrained through the pipe.

• This study seeks to

estimate the magnitude of

the effect from entrainment.

Collaborative Discussions

2. Assessment Method 4/19

• Technical Working Group Meetings • 1Jeff Paduan (Naval Postgraduate School)

• 2,3Erika McPhee-Shaw (MLML)

• 2Leslie Rosenfeld (MBARI/CeNCOOS)

• 1,3Pete Raimondi (UCSC)

• 1Peter von Langen (SWRCB)

• 1Andrew DeVogelaere (MBNMS/NOAA)

• 1Bridget Hoover (MBNMS/NOAA)

1. 19th July 2012 – Project overview and field work methods

2. 18th April 2013 – Update to status and oceanography discussion

3. 22nd Nov 2013 – Review results and discuss method

Intake Assessment Approach

Back-projections of modeled ocean

currents can predict both;

– Origins of those larvae; and/or

– Paths they took prior to

arriving at the intake site

This area is the source water area

and defines the extent of the

source water population.

Empirical Transport Model (ETM)

2. Assessment Method 5/19

Entrainment mortality is the

proportion entrained from the

source water population

Preliminary Intake Assessment

• Ichthyoplankton taxa data

based on 316(b) study done

for MLPP (Tenera, 2001) and

Diablo Canyon (Tenera, 2000).

• PEi was calculated using a

volumetric assumption.

• CODAR data from June 2010

to September 2011.

• ADCP data from MBARI M0

ADCP.

Preliminary Intake Assessment

2. Assessment Method 6/19

Data Collection

2. Assessment Method 7/19

Data Collection

2. Assessment Method 8/19

CODAR Surface

Currents

Data Collection

2. Assessment Method 9/19

Does ‘Deep’ Reduce Entrainment?

Average difference 0.624 larvae per m3

0 m to 25 m = 0.895 larvae per m3

25 m to 40 m = 0.271 larvae per m3

ANOVA: f = 50.44, p =< 0.0001

Highly significant difference

Deeper has less total larvae

Factors: Cycle, Survey, Station

Blocks: Sample pair

Transform: log(x+0.01)

3. Key Findings 10/19

Internal Wave at a Shelf Break

3. Key Findings 11/19

DWD/Tenera data

McPhee-Shaw et al 2013

Naples Reef, Santa Barbara

Internal Wave at a Shelf Break

3. Key Findings 12/19

Temperature

mooring

Canyon Regime

Can derive a

proportion of time

the canyon is in

one regime state

or the other

3. Key Findings 13/19

Canyon Regime

Warm

Cold

Transition

Warm regime had more larvae and more taxa.

However, taxa were essentially the same between the two regimes: G. lineatus

(white croaker), E. mordax (northern anchovy), CIQ goby and L. lepidus (bay

goby).

3. Key Findings 14/19

Shelf Water Volume

Northern anchovy White croaker CIQ goby Sanddabs

Blue rockfish complex KGB rockfish complex

3. Key Findings 15/19

Canyon Water Volume

3. Key Findings 16/19

ETM Output

Taxa PM

(25 MGD)

Entrainment

(25 MGD)

PM

(63 MGD)

Entrainment

(63 MGD)

Northern anchovy 0.025 % 15,224,457 larvae 0.062 % 38,365,623 larvae

White croaker 0.019 % 7,734,933 larvae 0.049 % 19,492,026 larvae

CIQ goby 0.043 % 1,085,411 larvae 0.109 % 2,735,235 larvae

Sanddabs 0.011 % 478,530 larvae 0.028 % 1,205,896 larvae

Blue rockfish 0.008 % 293,599 larvae 0.019% 739,870 larvae

KGB rockfish 0.003 % 42,701 larvae 0.009 % 107,607 larvae

Other fish NA 3,724,277 larvae NA 9,385,175 larvae

Total fish NA 28,583,908 larvae NA 72,031,432 larvae

Cancer crab NA 8,719,982 larvae NA 21,974,348 larvae

Market squid NA 142,038 larvae NA 357,935 larvae

3. Key Findings 17/19

Assessment Summary

4. Summary 18/19

1. Largest PM was for CIQ goby. This means 0.1% of the source water population

would be lost due to entrainment. However, adult habitat for CIQ goby is

shallow tidal channels higher in the slough. These larvae have been washed

out of the slough and are unlikely to recruit to the adult population. In the open

ocean they are also subject to increased natural mortality rates.

2. All the PM values are low (from 0.003% to 0.062%). This is because the rate of

entrainment is small relative to the source water volume. The source water

volume is also small relative to the total population size, which for some

species such as northern anchovy, ranges from Alaska to Baja.

3. Variation in annual recruitment due to competition, predation and many other

factors that do not include an ocean intake is much greater than these PM

values. These other mortalities rarely limit adult abundances. Therefore the

desalination entrainment mortality is negligible in terms of population change.

Objective 1: Assessment of Entrainment Effects

for Unscreened Intake

Assessment Summary

Objective 2: Assessment of Depth on Entrainment

4. Summary 19/19

1. There are less larvae at depths below 25 m and above 40 m than there are

larvae above 25 m deep. Therefore building the intake at depths that will

entrain larvae from the deeper depths will reduce entrainment numbers.

2. A further reduction in entrainment is obtained by locating the intake at the

Monterey Bay Canyon head. The internal tide at the canyon head advects

deep, cold canyon water with low concentrations of larvae and low diversity

into relatively shallow water from which the proposed intake will obtain it’s

feedwater, thus further reducing entrainment effects during these periods of

cold water advection.

3. The larval concentrations used in the ETM calculations did not include any

adjustments for the lower concentrations of larvae below 25 m where the intake

is proposed.