IssuesRelatedToWaterQualityInTheCapePointArea

December 13, 2006
L54(2380)
CAHAIGeneral
Memorandum
To: Thayer Broili, Chief of Resource Management, Cape Hatteras National Seashore
Subject: Issues related to water quality in the Cape Point area
Mr. Jim Luizer sent a couple of emails (May 1, 2006 and November 30, 2006; with attachments)
to the superintendent raising concerns about water quality issues in the Cape Point area and
potential impacts to groundwater resources of Hatteras Island. In this memo I will attempt to
address Mr. Luizer's concerns and briefly present results of the water quality sampling conducted
by NPS in the Cape Point area.
Total Tribalomethanes (TTHM)
The TTHM concentrations referred to in Mr. Luizer's letter are a result of the water treatment
process at the Dare County water treatment plant at Frisco. Tribalomethanes are produced by a
chemical reaction of chlorine and/or bromine with organic matter in water during the disinfection
process. It has no relation to any activity or resource management action by NPS.
Ken Flatt, Dare Co. Director of Utilities, verified these conclusions with respect to TTHMs in an
email to Thayer Broili (12/11/06). He stated, "The TTHM 'Notice of Violation' mailed out this
quarter had absolutely nothing to do with the Dredge Pond issue Mr. Luizer is discussing in his
email below. The high TTHM readings were caused by salt passage of the original reverse
osmosis membranes, which were replaced December 2005. The TTHM issue has been
completely resolved since the new membranes were installed. The TTHM readings, since the
installation of the new membranes, are March 2046 0.037 mg/l, July 2006 0.017 mg/l, and
September 2006 0.008 mg/l. All the readings are well below the .480 mg/l running annual
average limits. This information was included in the "Public Notification mailed to our
customers."
Mr. Flatt went on to write that, "(t)he Dredge Pond does not influence the brackish aquifer we
utilize for the RO process at the Cape Hatteras Water Plant." Brackish water for the reverse
osmosis plant is supplied from deep wells (greater than 200 feet deep) that are completed in a
confined aquifer underlying the surficial Buxton Woods aquifer (Mallin and others 2006). The
Buxton Woods aquifer is underlain by a 40 -foot thick confining layer of silty -to -clayey sand
(Anderson and others, 2000) that effectively isolates the deeper brackish aquifer from the Buxton
Woods aquifer.

Thus it appears that Mr. Luizer has already been provided information regarding the cause for
occurrence of trihalomethane in the public drinking water supply, the fact that the problem had
been corrected, and that the presence of tri_halomethane had absolutely no connection to any NPS
activity.
Potable water for NPS facilities on Hatteras Island is supplied by the Dare County Water
Department.
Groundwater Flow Directions
Mr. Luizer raised concerns about the potential for bacteria in the ponds in the Cape Point area to
contaminate groundwater resources underlying Buxton Woods and other privately -owned areas
on the north part of the island, This simply is not possible. Water table mapping by Winner
(1975), Anderson (1999), and others clearly show that the groundwater system underlying the
island forms a mound, with the high point of the mound near the center of the island, and that the
groundwater flows from the center of the island in all directions toward the shorelines. An
example of the water table maps produced by Dr. Anderson for his doctoral dissertation is shown
below. It clearly shows that groundwater flow in the Cape Point area is to the nearby shore areas,
generally in a southerly direction from the ponds at Cape Point.
Figure 311. Water -table contours derived from the two-dimensional Dupuit Flow
Model. Deflections in the contours at the two drained wetlands and the Frisco
Wellfield show the effects of water removal on water -table elevations. Transect t and
Transect 2 monitoring wells are shown as solid circles white the Frisco Wel{field
wells are shown as open circles. Drainage locations are shown as arrows.
From Anderson (1999)
2

It is impossible for water from the ponds in the Cape, Point area to flow uphill toward the center
of the island and contaminate the groundwater -underlying Buxton Woods or any other area of the
island. Water in the ponds in the Cape Point area slowly drains to the south, southeast, and
southwest through the sand sediments and discharges into the ocean at the shoreline.
Surface water and shallow groundwater on the island are part of the same water body. Ponds and
other surface water bodies occur where land surface dips below the level of the water table.
Much of the precipitation falling on the island infiltrates the sand sediments, recharging the
groundwater resources. Groundwater then flows radially from the top of the mound toward the
perimeter of the island. Since the flow of water is predominantly as groundwater flow, the
process is rather slow and it takes a long time to drain the water. The water table rises following
periods of high precipitation and then slowly recedes. That's why many people have the
perception that there is a flooding problem. The real problem is that infrastructure has been built
in low-lying areas that are flooded on a regular basis and are slow to drain.
Drainage of Cape Point Ponds
I have no information regarding past drainage practices for the ponds at Cape Point. We know
that the system of drainage ditches in the vicinity of the campground was operated until 2003,
with discharge to the ocean on the beach south of the campground. These ditches drained water
from the campground and areas to the north of the campground. There is no evidence that this
drainage system was ever connected to the ponds at Cape Point. In fact, the ponds at Cape Point
are on the south side of the main dune system. Drainage of the ponds to the ditch system would
have required that the water flowed uphill, as the elevation of the campground is higher than the
ponds at the Cape.
Temporary drainage ditches might have been constructed from the ponds to the ocean at some
time(s) in the past, although I have no record of this. My recollection from talking with park
personnel is that it wasn't done, or at least it wasn't done within the tenure of anyone working
there now. You might verify this by talking to Shelly Rollinson, John Wescott, or some of the
other "old-timers" on the Buxton maintenance staff.
High Water Levels in Wetland Areas
"Flooding" in wetland areas in the interior part of the island (e.g. Buxton Woods and Jenrette
Sedge) is a natural occurrence in response to abundant rainfall. Surface water drainage on the
island is poor to non-existent. The natural outflow of water from interior areas is by groundwater
flow through the sand sediments. This is a slow process that results in the perception of an
unduly long period of flooding. In fact, the drainage ditches that convey water from the Jennette
Sedge and Buxton Woods area to discharge into Pamlico Sound lessen the period of inundation
and are an unnatural perturbation of the natural hydrologic system.
The so-called "flooding problems" in the area of the campground, fish cleaning station, and
beach access ramps are natural occurrences. There is little that can be done to alleviate the
problem short of constructing a network of drainage ditches. NPS management policies, and
state and federal laws prohibit drainage of water from wetlands. NPS may have drained
floodwater from wetlands in the past, but that doesn't mean the practice is still acceptable.
3

NPS Water Quality Monitoring
NPS collected water samples from various surface water bodies in the Cape Point area in the Fall
and Winter of 2005 and again in the Summer and Fall of 2006. In 2005, the sampling was
designed to determine whether there was enterococci contamination of water in the drainage
ditches in the vicinity of the campground. Enterococcus is a bacteria found in the intestines of
warm-blooded animals, including humans. It is used as a bacterial indicator to determine the
extent of fecal contamination in water. The thought was that effluent from the septic leachfields
at the Cape Point campground could be a significant source of bacteria in nearby ponds and
drainage ditches. In 2006, the sampling program was revised to determine if there was any
significant difference in the presence of bacteria in surface water bodies in the Cape Point area
compared to more developed areas near the park entrance and Frisco. The 2006 sampling was
also designed to compare surface water bodies in developed and undeveloped areas. Since the
sampling programs in 2005 and 2006 covered different areas and used different numbering
systems for sampling stations, the results will be discussed separately.
2005 Data
In 2005, the monitoring program was primarily designed to determine whether water in the
drainages ditches in the vicinity of the campground was contaminated by effluent from the septic
leachfields in the campground. Samples were obtained from six sites (Figure 1) approximately
every two weeks from late -September through mid-January (Table 1). Samples were analyzed
for the number of enterococci colonies per 100 ml by the North Carolina Division of
Environmental Health, Shellfish Sanitation and Recreational Water Quality Program. Results of
the testing are presented in Table 1 and shown graphically on Figure 2.
Site S-2, the culvert at the main road 'h mile south of the ranger station consistently had the
highest bacterial concentration. This site is "upstream" of the campground.
Enterococci concentration at Site S-6, the Salt Pond at the southern tip of the cape, seemed to
show a correlation with the heavy rainfall in October 2005. There may be some mechanism by
which bacteria are washed from the surrounding land surface into the pond during heavy
rainfalls. Salt Pond is far from any potential impact from human use at the campground. Human
influence in the vicinity of Salt Pond would probably be limited to occasional visits by
birdwatchers and fishermen. The high concentration at S-6 on for the Oct 24 sample is
anomalous. All other samples from that date showed decreased enterococci concentration,
probably due to dilution by the large amount of rain that fell in the preceding 24 hours.
The remainder of the sampling sites (S-1, S-3, S-4, and S-5) are located in the system of drainage
ditches "downstream" of the campground. All of these sites show similar variation in the
concentration of enterococci. Enterococci concentrations for the first sampling period range
from about 10-100 colonies per 100 ml. The concentration increases significantly for the second
set of samples on Oct. 10, probably in response to rain the preceding 24 hours that may have
flushed bacteria from the land surface into the ditches, or perhaps because there was enough rain
to get stagnant water flowing through the system again. Enterococci concentrations decreased at
the Oct. 24 sampling even though it also was preceded by heavy rainfall. Perhaps much of the
M

bacteria had been flushed through the system by the earlier rain or perhaps the large amount of
rainfall effectively diluted the bacterial concentration. Enterococci concentrations remained
within the 10-100 colonies per 100 ml range throughout the remainder of the fall and winter.
Concentrations appear to decrease as the temperature got colder later in the year.
Enterococci concentrations at sampling sites "downstream" of the campground were generally
the same or lower than the "upstream" and control sites. It appears that the septic leachfields in
the campground are not a significant source of fecal indicator bacteria contamination to nearby
surface water bodies.
2006 Data
The 2006 monitoring program was designed to determine whether there is a significant
difference in the presence or concentration of bacteria in surface waters in the Cape Point area
compared to surface waters near the park entrance in the Frisco area. Additionally, some of the
sampling sites on the south part of the island are very remote and are not affected by human
activities.
Seven sites were sampled. Site S-1, the drainage ditch near J loop in the campground was
sampled every two weeks. This site was chosen as it is close and slightly "downstream" of the
septic leachfields in the campgrounds. The other six sites were sampled approximately monthly
as two groups of three sites. This allowed us to sample the ditch at J loop and three other sites
every two weeks. Sample site locations are shown on Figure 3. Samples were analyzed for the
number of enterococci colonies per 100 ml by the North Carolina Division of Environmental
Health, Shellfish Sanitation and Recreational Water Quality Program. Results of the testing are
presented in Table 2 and shown graphically on Figure 4.
The data for 2006 show very high concentrations of enterococci at two sites on August 21. Site
S-2 is Horsehoe Pond, an area that is not affected by human activities. Site S-7 is St. Peters
Ditch south of the intersection of Forest Road and Hwy 12. St. Peters Ditch drains heavily
developed privately -owned areas and it's not unexpected to find high concentrations of
enterococci at this location during the peak of the summer. The high concentration of
enterococci in the sample from Horsehoe Pond can only represent natural contamination by birds
or wildlife.
All of the samples from St. Peters Ditch (S-7) have higher concentrations (generally 250-300
colonies/100 ml) than what has been generally observed at other sites in 2005 and 2006. The
higher concentrations of enterococci are likely due to the ditch draining heavily developed areas
with many septic leachfields.
Two of the samples collected on Sept. 6 had elevated concentrations of enterococci. These
higher concentrations coincided with rain in the 24 hours preceding sample collection. This
continues the observations from 2005 of elevated enterococci concentrations immediately
following rainfall events.
5

The remainder of the data fall in the range of 10-100 colonies per 100 ml that was observed as
the general background level.
Conclusions
There is no evidence to indicate the septic leachfields at the Cape Point campground contribute
to the presence or concentration of enterococci bacteria in adjacent surface water bodies. Most of
the samples are within the range of 10-100 colonies/1 00 ml. Most of the higher concentrations
are correlated to preceding rainfall that might contribute to flushing bacteria into the surface
waters, or mobilizing bacteria already present. There are a few samples that appear to be
anomalously high, for which no explanation is offered.
The only site that had bacteria concentrations consistently above background was St. Peters Ditch
at the intersection of Forest Road and Hwy 12. St. Peters Ditch drains groundwater from
heavily -developed, privately -owned areas having individual septic leachfields.
References Cited
Anderson, William P., Jr., 1999, The Hydrology of Hatteras Island, North Carolina, Ph.D.
Dissertation, unpublished, North Carolina State University, Raleigh, NC, 293 pp.
Anderson, W.P., Jr., 2002, Aquifer Salinization FromStorm Overwash, Journal of Coastal
Research, 18-413-420.
Mallin, Michael A., Matthew R. McIver, and Virginia L. Johnson, 2006, Assessment of Coastal
Water Resources and Watershed Conditions at Cape Hatteras National Seashore, North
Carolina, National Park Service Technical Report NPS/NRWRD/NRTR-2006/351, 75 pp.
Winner, Jr., M.D., 1975, Ground -Water Resources of the Cape Hatteras National Seashore,
North Carolina, U.S. Geological Survey Hydrologic Investigations Atlas HA -540, 2 sheets.
If there are any questions regarding this report, please call me at (970)-225-3515.
cc: 2380 -- Joel Wagner, Bill Jackson
SER — Cherry Green
CAHA — Karen Sayles
0

Figure 1. Location of sampling sites for the 2005 monitoring program.

Table 1. Results of 2005 Water Qual(ty Monitoring.
Precip
Enterococci
Sbn.No.
Location ofStation
Date
Time
|amt24hrs
(K8PN)/100m|
S1
Ditch —40Oyards GVVoffloodgate
9/26/05
8:25
0.07"
53
82
Culvert atroad 1/2mile S,ofRanger Station
9/26/05
7:55
8.07"
1184
S3
Ditch —3Oyards NEoffloodgate
9t28/05
8:15
U.07"
75
S4
Ditch —3Oyards SVVoffloodgate
9V26/05
8:17
0.07"
87
85
Center ufditch draining tuocean
9/20/05
8:45
0.07"
18
S6
Salt Pond at south end
9/26/05
9:00
0.07"
<10
Si
Ditch —4OOyards SVVoffloodgate
10/10/05
7:38
2.7"
207
82
Culvert etroad >6mile Sof Ranger Station
10/10/05
7:20
2.7"
097
S3
Ditch —30yards NEnffloodgate
10/10/05
7:35
27'
207
S4
Ditch ~-3Oyards SVV of floodgate
10/10/05
7:40
2.7"
344
S5
Center ofditch draining toocean
18/10/05
7:52
2.7"
324
SD
Salt Pond at south end
10/10/05
8:00
2.7"
231
S1
Ditch —4OUyards SVVmf floodgate
10/24/85
7.40
4.8"
53
S3
Culvert airoad \6mile Scf Ranger Station
10/24/05
7:15
4.8"
111
83
Ditch —3Uyards NEoffloodgate
10/24/05
7:30
4.8"
64
S4
Ditch —3Uyards SVVoffloodgate
10/24/05
7:32
4.8"
53
S5
Center ofditch draining to ocean
10/24/05
7:45
4.8"
10
SG
Salt Pond otsouth end
10/24/05
7:50
4.8^
591
Si
Ditch —4DOyards SVVoffloodgate
11/7/05
7:05
0.0"
75
S2
Culvert atroad }6 mile S ofRanger Station
11/7/05
6:43
D.O~
192
S3
Ditch —3Uyards NEoffloodgate
11/7/05
6:55
0.0"
QB
G4
Ditch —3Oyards SVVoffloodgate
11/7/05
7:00
D.0"
20
SS
Center ofditch draining tmocean
11/7/05
7:23
0.8"
53
86
Salt Pond at south end
11/7/05
7:27
0.01,
42
Si
Ditch —4OOyards SVVcf floodgate
11/21/05
7:43
0.02"
10
S2
Culvert atroad }6mile SofRanger Station
11C21/05
7:23
O.O2"
99
S3
Ditch —3Dyards NEoffloodgate
11/21/05
7:35
0.02"
20
S4
Ditch —3Oyards SVV of floodgate
11/21/05
7:38
O.O2"
10
S5
Center ofditch draining toocean
11/21/05
8:00
0.02"
10
SM
Salt Pond atsouth end
11/21/05
8:14
0.02"
10
S1
Ditch —4UOyards SW of floodgate
12/5/D5
7:15
0.68^
20
S2
Culvert at road 1/2 mile ofRanger Station
12/5J05
7:00
0.68"
87
S3
Ditch —3Oyards NEoffloodgate
12/5/U5
7:10
0.68"
<10
S4
Ditch —3Oyards SVVoffloodgate
12-/5/05
7:20
0.681'
10
S5
Center ofditch draining toocean
12/5/05
7:34
0.68"
10
S6
Salt Pond at south end
12/5/05
7:40
0.68"
<10
Si
Ditch —4O0yards SVV of floodgate
12/19/05
8:00
0.93"
<10
G2
Culvert atroad }6 mile ScfRanger Station
12/19/05
7:40
0.98"
10
S3
Ditch -3O yards NEoffloodgate
12Y19/05
7:58
0.93"
10
S4
Ditch —3Oyards SVV of floodgate
12Y19/05
7:55
0.93~
12
G5
Center nfditch draining tnocean
12/19/05
8:25
0.93"
31
S8
Salt Pond mtsouth end
12/19/05
8:35
0.83"
10

Table 1 (cont). Results of 2005 Water Quality Monitoring.
Preoip
Enterococci
Stn.No.
Location ofStaUnn
Date
Time
|oed24h/s
(K4PN)/100m|
Si
Ditch —4OOyards SVVnffloodgate
01/08/06
7:38
0.86°
<10
S2
Culvert atroad }6mile SnfRanger Station
01/03/06
717
0.86"
64
S3
Ditch —JOyards NEoffloodgate
01/03/06
7:31
0.86"
10
S4
Ditch —3Oyards SVVoffloodgate
D1/03/08
7.33
0.86"
10
S5
Center ofditch draining 1nocean
01/03X00
7:53
0.80"
10
S6
Salt Pond at south end
01/03/06
8:05
0.86"
10
S1
Ditch —4UOyards SVVoffloodgate
01/16/08
7:45
trace
<10
S2
Culvert otroad 1/2mile Go[Ranger Station
01/16/06
7:27
trace
18
S3
Ditch —3Oyard8'NEoffloodgate
01/16/06
7:39
trace
<10
84
Ditch —3Oyards 8VVo[floodgate
01/18/06
7:40
trace
<10
35
Center ofditch draining tuocean
01/18/08
8:08
trace
10
S6
Salt Pond otsouth end
01/18/08
8:15
trace
<10

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Figure 3. Location of sampling sites for the 2006 sampling program.
11

Table 2. Results of 2006 Water Quality Monitoring
Site #
Location mfsample station
Date Time
Precip
Enterococci
last 24
/MPNV100m|
ms
S-7
Ditch @ Forest Rd & H12
8/21/06
6:52
0,00"
831
S-1
Campground ditch "J"loop
B/21/06
8:37
O.00°
<10
S-2
Horseshoe Pond
8C21/06
6:30
0.00"
1398
Air temp: 7SF
G-1
Campground ditch "J"loop
0/06/06
7:40
0.64"
364
G-2
Horseshoe Pond
9/06/06
7:43
0.64"
iU
G-3
South Beach drain pond
B/OB/OB
7:25
0,64"
31
S-4
Fish cleaning station pond
8/00/00
7:15
0,64"
384
A1rtermp: 73 F
G-1
Campground ditch "J"loop
0/18/08
8:54
0.00"
<10
S-5
Pond @ Open Ponds Rd
9/18/06
9:20
D.OD"
137
S -B
Entrance RdPond
6x18/06
8:56
0.00"
10
S-7
Ditch @ Forest Rd & H12
9/18/06
8:59
0.00"
254
Air temp: 76 F
S-1
Campground ditch ~J^loop
10/02y06
9:10
0.00"
31
S-2
Horseshoe Pond
10/02/06
9:15
D.00°
20
S-3
South Beach drain pond
10/02/06
8:35
0.00"
31
S-4
Fish cleaning station pond
10/02A06
8:55
0.00"
<10
Air temp: 72 P
S-1
Campground ditch ^J"loop
10/16/06
9:33
D.00"
30
S-5
Pond @ Open Ponds Rd
1016/06
9:10
0.00^
^18
S -G
Entrance Rd Pond
10/16/06
8:51
O.OU~
<10
S-7
Dihuh@ Forest RdQH12
10/18/06
8:54
0.00"
271
Air temp: 62 F
S-1
Campground ditch ^J^loop
10/30/06
9:04
O.00"
31
S-2
Horseshoe Pond
10/30/06
B:DO
O.00~
10
S-3
South Beach drain pond
10/30/00
9:23
0,00"
42
S-4
Fish cleaning station pond
10/30/06
9:37
0.0O"
81
Air temp, 65F
S-1
Campground ditch ^J^loop
11/13/06
9:28
0.51"
87
S-5
Pond @ Open Ponds Rd
11/13/06
9:06
O. 51"
31
S -B
Entrance Rd Pond
11/13/06
8:50
O. 51"
20
S-7
Ditch @ Forest Rd &H12
11/13/06
8:48
0.51"
288
Air tem p: 51 F
S-1
Campground ditch "J"loop
11/27/06
7:47
0. 00"
75
G'2
Horseshoe Pond
11/27/08
7:43
0.00"
<10
S-3
South Beach drain pond
11/27/06
8:04
U.00~
10
B-4
Fish cleaning station pond
11/27106
7:29
0.00~
31
Air temp: 57F*heavy rain & flooding 11/21-1i/23
12

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14