CCU’s Environmental Quality CCU’s Environmental Quality Lab: Investigation of Ocean Lab: Investigation of Ocean Outfalls in Myrtle Beach and Outfalls in Myrtle Beach and North Myrtle Beach, SCNorth Myrtle Beach, SCJoseph Bennett and Susan Libes

Stormwater Pipes

Pipes on Beach 2 to 3 inch diameters 100+

Outfall Pipes 60+ inch diameters 1000+ ft offshore Myrtle Beach

25th Ave S (June 2003) 53rd Ave. N (delayed) 14th Ave. N. (Fall 2005)

North Myrtle Beach 6th Ave. S. (installed 2004) 33rd Ave S. and ? One in construction

SC DHEC OCRM Permit Requirements

Onshore Stormwater Quality StudyCharacterize composition of outfall emissionsTreatment devices

In-Situ Water Quality Study Evaluate the impact of runoff on nearshore

?FlowsDispersionDischarge

Potential Impacts of Concern

BacteriaSwimming

EutrophicationDissolved Oxygen

?AnimalsToxicsSalinity

Potential Parameters

Enteroccoci Dissolved Oxygen Nutrients Oxygen Demanding Substances (BOD5) Chlorophyll Turbidity Salinity Temperature

Potential Sampling Strategies

Following rain eventsOnshoreOffshore

Controls: What is normal for Long Bay?Dry weather(onshore and offshore)?Geographic

Pre and post constructionSites with little runoffSites with lots of runoff

Stormwater Runoff Sources

Tidal Creeks (swashes)Withers Swash: 35 to 40 cfs non-rainMidway Swash: 10 to 15 cfs non-rain

Pipes on Beach FaceOutfall Pipes

Jan

Jun

Nov

South

900

200

500

1200

1900

Withers Swash

25th S

Midway Swash

0

1000

2000

3000

4000

5000

6000

En

tero

cocc

i G

eom

etri

c M

ean

(

CF

U/1

00 m

L)

Meters N or Sfrom 25th S

Enterococci in Stormwater Runoff Around 25th S in 2004

Jan

May

Sep

South

900

200

500

1200

1900

Withers Swash

23rd S

25th S

27th SMidway Swash

Nash Dr.

0

100

200

300

400

500

600

700

En

tero

co

cc

i G

eo

me

tric

Me

an

(C

FU

/10

0 m

L)

Met

ers

N o

r S

from

25t

h S

Enterococci in Surf Zone Around 25th S in 2004

Nor

th

1950

1725

1500

1275

105082

5

600

375

15075300

525

750

975

Sou

th

0

450

Nash Dr.

Midway Swash

23rd S

Withers Swash(12,997 CFU/100 mL)

Outfall

0

50

100

150

200

250

Enterococci (CFU/100 mL)

Distance Up or Downshore from Pipe Crossing on Beach (m)

Distance Offshore(m)

Expanded Surface Distribution of Enterococci Around 25th S Outfall Dischargeon 10/4/04, >1" Rain in Previous 24 Hours and >3" Rain in Previous 72 Hours

Longshore Flow

What is normal?What is acceptable? Impacts

Water Quality Animals

Fisheries Natural populations

Loading Beach Pipes Outfall Pipes Swashes

Management Regulatory Criteria

Benchmarks Thresholds

Monitoring

0

1

2

3

4

5

6

24 26 28

De

pth

(m

)

0

1

2

3

4

5

6

34.5 35.0 35.5 36.0

0

1

2

3

4

5

6

0 1 2 3 4 5 6

De

pth

(m

)

0

1

2

3

4

5

6

0 20 40 60 80 100

DO (ppm) % Saturation

Temperature (oC) Salinity

2nd Ave N. Pier 7/20/2004

Bottom Water Quality: Longitudinal Transect Along Pier

24.5

25.0

25.5

26.0

26.5

27.0

27.5

28.0

0 2 4 6Bottom Depth (m)

Te

mp

era

ture

(o

C)

0

1

2

3

4

5

6

0 2 4 6Bottom Depth (m)

DO

(p

pm

)

34.6

34.8

35.0

35.2

35.4

35.6

35.8

36.0

0 2 4 6Bottom Depth (m)

Sa

linit

y

0

20

40

60

80

100

0 2 4 6Bottom Depth (m)

% S

atu

rati

on

0 m

3 m

?Low DO5 m

Longitudinal Model of Hypoxic Zone

Pier

+ 100 to 200 m

Time-line

Surface Cooling: July 1 – July 30 Rain fall

7/9, 1.0 inches 7/18, 2.2 inches

Sampling 7/20: 2nd Ave N and Springmaid 7/22: 2nd Ave N and Springmaid 7/23: Cherry Grove and Apache + DNR transects

Flounder Jubilee July 15 – 23 July 23 – 28: tapered down

0.0

0.5

1.0

1.5

2.0

2.5

6/1

6/5

6/9

6/1

3

6/1

7

6/2

1

6/2

5

6/2

9

7/3

7/7

7/1

1

7/1

5

7/1

9

7/2

3

7/2

7

7/3

1R

ain

(in

)

Withers Swash Midway Swash

Flounder runs start

Cold Event

Hypoxia first observed

Rain Fall Amounts Near Locations of Major Freshwater Input to Surf Zone

Time-line

Surface Cooling: July 1 – July 30 Rain fall

7/9, 1.0 inches 7/18, 2.2 inches

Sampling 7/20: 2nd Ave N and Springmaid 7/22: 2nd Ave N and Springmaid 7/23: Cherry Grove and Apache + DNR transects

Flounder Jubilee July 15 – 23 July 23 – 28: tapered down

DO Concentration in Bottom Water During Hypoxic Event

0

1

2

3

4

5

6

GardenCity

Surfside MyrtleBeach

State Park

SpringmaidPier

2nd Ave N.MB

ApachePier

CherryGrove Pier

DO

(p

pm

)

7/20/047/22/047/23/04

NOAA Estuarine Eutrophication Criteria Biological Stress >2 ppm, < 5 ppmHypoxic >0 ppm, < 2 ppmAnoxic 0 ppm

Off Shore

8.01

8.07 8.06

8.20

8.09

7.83

8.02

7.6

7.7

7.8

7.9

8.0

8.1

8.2

8.3

Garden City Garden City Surfsidenearshore

Surfsideoffshore

Myrtle BeachState Park

Pier

2nd Ave Pier Apache Pier,nearshore

Mea

n p

HpH measurements along Grand Strand, July 23, 2004

Surf Zone and Near Shore Dissolved Oxygen Percent Saturation

20

30

40

50

60

70

80

90

100

110

2/26 3/12 3/27 4/11 4/26 5/12 5/27 6/11 6/26 7/11 7/27 8/11

Sampling Date

Per

cen

t S

atu

rati

on

of

DO

2nd Ave N Springmaid Pier Surf Zone (25th Ave N)

Cherry Grove Pier Apache Pier

Cold Event

Bottomwater

Rain No Rain

Rain

Time-line

Surface Cooling: July 1 – July 30 Rain fall

7/9, 1.0 inches 7/18, 2.2 inches

Sampling 7/20: 2nd Ave N and Springmaid 7/22: 2nd Ave N and Springmaid 7/23: Cherry Grove and Apache + DNR transects

Biotic Impacts Flounder Jubilee Benthic invertebrate kills at Huntington Beach and Pawleys

Island

Causative Agents

Coastal UpwellingSummer CoolingPlankton Bloom

Elevated Chlorophylls Nutrients

Stormwater RunoffPipes and swashes discharge on beachOff-shore discharge pipes

Raw Sewage Spill

Surf Zone and Near Shore Chlorophyll a Levels

0

10

20

30

40

50

60

70

80

2/26 3/12 3/27 4/11 4/26 5/12 5/27 6/11 6/26 7/11 7/27 8/11

Sampling Date

Ch

l a (

pp

b)

2nd Ave N Springmaid Pier Surf Zone (25th Ave N)

Cherry Grove Pier Apache Pier

NOAA Estuarine Eutrophication Criteria Surface ConcentrationHypereutrophic >60 ppbHigh >20 ppb, < 60 ppbMedium >5 ppb, < 20 ppbLow >0 ppb, <5 ppb

Bottomwater

Cold Event

Rain No Rain Rain

Total Nitrogen Concentration in the Surf Zone and Near Shore

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

4/23 5/3 5/13 5/23 6/2 6/12 6/22 7/2 7/12 7/22 8/1Sampling Date

Co

nce

ntr

atio

n (

pp

m N

)

2nd Ave N Springmaid Pier Surf Zone (25th Ave N)

Cherry Grove Pier Apache Pier

NOAA Estuarine Eutrophication Criteria Maximum Dissolved Surface ConcentrationHigh >1ppmMedium >0.1 ppm, < 1 ppmLow >0 ppm, <0.1 ppm

Bottomwater

Cold Event

Total Phosphorus Concentration in the Surf Zone and Near Shore

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

4/23 5/3 5/13 5/23 6/2 6/12 6/22 7/2 7/12 7/22 8/1Sampling Date

Co

nce

ntr

atio

n (

pp

m P

)

2nd Ave N Springmaid Pier Surf Zone (25th Ave N)

Cherry Grove Pier Apache Pier

NOAA Estuarine Eutrophication Criteria Maximum Dissolved Surface ConcentrationHigh >0.1ppmMedium >0.01 ppm, < 0.1 ppmLow >0 ppm, <0.01 ppm

Bottom water

Cold Event

Nitrogen to Phosphorus Ratio in the Surf Zone and Near Shore

0.0

20.0

40.0

60.0

80.0

100.0

120.0

4/23 5/3 5/13 5/23 6/2 6/12 6/22 7/2 7/12 7/22 8/1

Sampling Date

N/P

2nd Ave N Springmaid Pier Surf Zone (25th Ave N)

Cherry Grove Pier Apache Pier

Bottom water

Cold Event

N deficient growth

P deficient growth

Guildford and Hecky, 2000

Causative Agents

Coastal UpwellingSummer coolingPlankton Bloom

Elevated Chlorophylls Nutrients

Stormwater RunoffPipes and swashes discharge on beachOff-shore discharge pipes

Raw Sewage Spill

Causative Agents Coastal Upwelling

Summer cooling Plankton Bloom

Elevated Chlorophylls Nutrients

Stormwater Runoff Pipes and swashes discharge on beach Off-shore discharge pipes

Raw Sewage Spill in NMB July 13: few hundred gallons July 21: 5000 gallons

Is this a one-time event?

Should we be worried?

-

200,000

400,000

600,000

800,000

1,000,000

1,200,000

Po

pu

lati

on

Es

tim

ate

1990 1995 2000 2005 2010 2020 2030

Year

Horry County Population Growth Projections

Permanent Overnight Day

Future Frequency of Hypoxia

Frequency of UpwellingGlobal Climate Change

Stormwater RunoffGlobal Climate Change Increase in population & impervious cover

Potential Impacts

Hard Bottom CommunitiesFisheries

OverfishingHarmful Algal Blooms

< 0.5 m sediment cover

Potential Hard Bottom Habitat

3 m

Typical 4 s waves along Grand Strand constrain wind mixing to upper 3 m (Gayes, pers. comm.)

Hard Bottoms start

Potential Impacts

Hard Bottom CommunitiesFisheries

OverfishingHarmful Algal Blooms

Needs

Monitoring Define normal for Nearshore Waters

Now using estuarine criteriaHow much of these events are natural

Translate this into management guidelinesReduction of nonpoint loads

Acknowledgments

Bob Van Dolah, Mel Bell, George Reikerk, Dean Cain, SC DNR

Denise Sanger, SC DHEC OCRM Alan Lewitus, South Carolina Algal Ecology

Laboratory Bob Pender, Ryan Day, Burroughs and Chapin

Center for Marine and Wetland Studies

Surf Zone and Swashes, Myrtle Beach, SC

0

50

100

150

200

250

300

3/27 4/11 4/26 5/12 5/27 6/11 6/26 7/11 7/27

Sampling Date

Mo

lar

N t

o P

Drainage Basin 2 (ditch) Drainage Basin 1 (pool)