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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)