Quantification of
 

Microplastics


on National Park Beaches
 

06/01/2015 - 05/31/2017 

Principal Investigators: 

Stefanie L. Whitmire, Ph.D.
 

Baruch Institute of Coastal Ecology & Forest Science, Clemson University
 

Skip J. Van Bloem, Ph.D.
 

Baruch Institute of Coastal Ecology & Forest Science, Clemson University
 

NPS Technical Coordinators: 

Catherine Anna Toline, Ph.D. 

Southeast Regional Marine Scientist / Oceans Program Coordinator 

Cliff McCreedyMarine Resource Management Specialist 

Prepared for: 

Marine Debris Program 

Office of Response and Restoration 

National Oceanic and Atmospheric Administration 

Contract GSI-CU-1505 

Photo: National Parks Service, Kalaupapa National Historical Park 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1. INTRODUCTION

Plastic pollution is a global environmental concern. Most plastics are durable and degrade 

slowly, so discarded plastic remains in the environment for a long time, thus becoming an 

environmental hazard. Risks from large plastic debris, such as entanglement of marine life and 

ingestion by shorebirds, reptiles and fish, often cause injury or death and has been welldocumented in marine systems (Derraik 2002; Gall and Thompson 2015). Plastic debris washing 

onto shore or into developed areas has economic impacts on tourism and industry on top of 

ecological effects (Avio et al. 2016, Critchell and Lambrechts 2016). There is no lack of plastics 

in society. In 2010, there was 275 MT of plastic waste generated globally (nearly 100 pounds per 

person) and another 270 MT of new plastic resins were produced (Jambeck et al. 2015). If even a 

small percentage of this annual plastic production is released into oceans, lakes, and rivers, it can 

accumulate into large amounts of plastic debris, as has been shown by many marine debris 

studies. 

Scientists are not only finding large plastic debris in the ocean and around the globe, but also 

microplastics. Microplastics are defined as manmade plastic particles less than 5 mm in size that 

are mostly the result of either the breakdown of larger plastic items, such as water bottles and 

fishing line, or from manufacturing of small particles including cosmetic beads added to facial

scrubs and toothpastes. Fibers from clothing such as fleece are also a substantial portion of 

microplastics. 

Microplastics enter the ocean either indirectly from land-based run-off or through river transport,

or as larger pieces already drifting in the ocean that degrade into smaller pieces (Browne et al.

2010, Yonkos et al. 2014). These very small pieces have been found in zooplankton, coral,

copepods, marine worms, filter feeders, fish, and other organisms that serve as prey for larger 

species (Cole et al. 2013, Rochman et al. 2014, Wright et al. 2013, Setala et al. 2014). This is not 

surprising since microplastics are often the same size as food particles for these organisms. 

While studies continue to be published on the fate and effect of microplastics on an organism’s

physiology and the potential biomagnification in food webs, research has already demonstrated 

ingestion and potential toxicological risks (e.g. Browne et al. 2013, Wright et al. 2013, Farrell

and Nelson 2013, Setala et al. 2014, Rochman et al. 2014, Avio et al. 2015). When plastic is 

manufactured, additives are commonly used such as phthalates (plasticizers to enhance 

flexibility), a possible carcinogenic compound, and bisphenol A (BPA- added to polycarbonate

and plastic resins), an endocrine disrupter. Microplastics can also adsorb persistent organic 

pollutants, like polychlorinated biphenyl (PCB - e.g. coolants), which are present in many coastal 

environments. The fate and impacts of ingesting these small particles with these chemicals on 

whole ecosystems is an emerging topic for research and management (Besseling et al. 2013, 

Chua et al. 2014, Rochman et al. 2014, Koelmans et al. 2013, Koelmans et al. 2016). The 

introduction of these chemicals could have large implications for coastal food webs and 

potentially humans. 

The purpose of this project is to quantify microplastic loads at single sites on selected beaches at 

a continental scale to better understand microplastic distribution. A collaborative effort with the 

National Park Service and NOAA Marine Debris Program provided the opportunity to sample a 

wide geographic distribution of coastal beaches to quantify microplastic loads in a snapshot of 

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time. Beaches can capture microplastics from both open water bodies (oceans or lakes) and 

riverine systems. Additionally, beaches are dynamic systems, with constant movement of sand 

and other particles like shells, glass, and plastic. 

While the type of manmade material found was not determined, the techniques employed 

maximize the separation of microplastics from sand, so we assumed that mostly plastic was 

captured during this process as heavier materials, even if small, would have been separated from 

plastics. Given the ubiquitous nature of the microplastics concern, sampling beaches using a 

standard protocol provides an opportunity to compare relative amounts of microplastics across a 

wide geographic region. The overall approach of a one-time sampling at multiple sites across a 

broad geographic area allows us to determine how widespread and variable microplastic 

pollution is and to begin to make inferences about sources and sinks. Data produced from this 

study should be used to gain a better understanding of where microplastics are located in the 

environment and an idea of the range of loads found along US coasts. However, NPS units

should not use this single study to make strong inferences about the immediate risk of 

microplastics to wildlife and human health at their sites. 

2. MATERIALS AND METHODS

2.1. Field Sampling Collections

Thirty-seven coastal sites from 35 National Parks Service (NPS) units were selected for this 

study. The sites include the Northeast Region, Great Lakes, West Coast and Pacific Islands, and 

the Alaska Region (Table 1, Figure 1). Sites in the southeast US were part of a previous study 

(Chow et al. 2016). and not resampled for this project. Sampling locations within a park were 

selected by park staff based on where they consistently observed large marine debris. All sand 

samples were collected by NPS staff or NPS volunteers using sampling kits provided by the 

Baruch Institute of Coastal Ecology and Forest Science. The sampling kits included a written 

procedure with a visual illustration (Supplement A), a metal sampling ring, a metal spoon, 

premade aluminum foil bags, a blank data sheet (Supplement A), and a box with return postage 

(Chow et al. 2016). Samples were collected at low tide along a 50-meter transect parallel with

the shore between the high and low tide lines. To keep sample sizes consistent, the metal ring 

with a 25-cm diameter and 1.5-cm height (equivalent volume = 736 cm3

) was pressed into the 

top sand layer until the upper rim of the ring was flush with the sand; material within the ring 

was carefully collected to the bottom of the rim using the metal spoon and subsequently

transferred into an aluminum foil bag (depth of sample is 1.5 cm). A total of 10 samples along 

the 50-m transect were collected from each site, with at least 1 m between each sampling point.

The bags were carefully folded and packed, and shipped back to the laboratory at the Baruch 

Institute of Coastal Ecology & Forest Sciences in Georgetown SC for processing. Sand samples 

were collected from June to December 2015. Due to weather and remote access in the Alaska 

region, three locations there were sampled from June to August 2016 (Supplement Table B3). 

2.2. Microplastic Isolation and Quantification

Beach sediments were dried at 70°C for 48 hours and then sifted through a 4.75-mm brass mesh 

sieve and then a 2-mm brass mesh sieve to remove larger pieces of debris and organic matter. 

The amount of microplastics from 2 – 4.75 mm was visually counted and recorded in the lab, and 

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Table 1. The region of the thirty-seven National Park Units sampled representing 35 National

Parks. NPS unit abbreviation and geographical coordinates of sampling locations are listed. 

was on y seen at tes teague s t ona t s t ona

Recreation Area, Gateway National Recreation Area at Sandy Hook, Santa Monica National

Recreation Area, Kalaupapa National Historical Park, and the National Park of American Samoa) 

l 6 si (Assa I land Na i l Seashore, Bos on Harbor I lands Na i l 

Region Park

Park

Abbreviation GPS Coordinates

Alaska 

Aniakchak National Monument & Preserve ANIA 56.683414 -157.550116 

Bering Land Bridge National Preserve BELA 66.250086 -166.066845 

Cape Krusenstern National Monument CAKR 67.066850 -163.343233 

Glacier Bay National Park & Preserve GLBA 58.450867 -135.896033 

Katmai National Park & Preserve KATM 58.441700 -154.069883 

Kenai Fjords National Park KEFJ 59.727750 -149.927440 

Klondike Gold Rush National Historical Park KLGO 59.488794 -135.357424 

Lake Clark National Park & Preserve LACL 59.979251 -152.660911 

Sitka National Historical Park SITK 57.045080 -135.311040 

Wrangell St. Elias National Park & Preserve WRST 59.703650 -140.254400 

Midwest 

Apostle Islands National Lakeshore APIS 46.976567 -90.859550 

Grand Portage National Monument GRPO 47.962994 -89.682527 

Indiana Dunes National Lakeshore INDU 41.709698 -86.931226 

Isle Royale National Park ISRO 47.890898 -89.001956 

Pictured Rocks National Lakeshore PIRO 46.659787 -86.177646 

Sleeping Bear Dunes National Lakeshore SLBE 44.945422 -85.818134 

Northeast 

Acadia National Park ACAD 44.329099 -68.182790 

Assateague Island National Seashore ASIS 38.276093 -75.118890 

Boston Harbor Islands National Recreation Area BOHA 42.316913 -71.010492 

Cape Cod National Seashore CACO 42.002410 -70.022130 

Fire Island National Seashore FIIS 40.686275 -72.998518 

Gateway National Recreation Area (Jamaica Bay) GATE JB 40.561040 -73.883454 

Gateway National Recreation Area (Sandy Hook) GATE SH 40.471999 -73.997320 

Gateway National Recreation Area (Staten Island) GATE SI 40.530900 -74.134800 

West 

coast Olympic National Park OLMY 48.031784 -124.682087 

Cabrillo National Monument CABR 32.668950 -117.244700 

Channel Islands National Park CHIS 34.063375 -120.374063 

Golden Gate National Recreation Area GOGA 37.736000 -122.507350 

Lewis and Clark NHP LEWI 46.094638 -123.941734 

Point Reyes National Seashore PORE 38.026642 -122.960722 

Redwood National Park REDW 41.300311 -124.090360 

San Juan Island National Historical Park SAJH 48.459110 -123.023660 

Santa Monica National Recreation Area SAMO 34.041899 -118.570992 

Pacific Hawai’i Volcanoes National Park HAVO 19.270124 -155.253971 

Islands 

Haleakala National Park HALE 20.757000 -155.983000 

Kalaupapa National Historical Park KALA 21.211460 -156.966130 

National Park of American Samoa NPAS -14.251240 -170.672320 

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(Table B2). Since the amount of microplastics seen in the 2 - 4.75 mm size range was minimal

(less than 1 piece per sample on average), these items were not considered in the analysis. The 

sieved samples were stored in glass jars with metal lids until further analysis. Four dried sieved 

sand samples from each site were randomly selected for microplastic isolation by density

separation (Thompson et al. 2004, Hidalgo-Ruz et al. 2012). Dried sand (200 g) was mixed with

250 ml of a filtered concentrated saline solution (NaCl 1.27 g/ml) in 500 ml glass canning jars. 

Filtration of the saline solution was necessary to remove microplastic contaminants from the salt.

The glass jars were sealed with metal lids and shaken for 3 minutes. After at least 2 hours of 

settling, the supernatant was removed with a metal baster and filtered through a glass filtration 

system and a sterile gridded 0.45 um nitrocellulose filter (Millipore). Extreme care was taken to 

not contaminate the samples by keeping the filtration system covered and washing the transfer 

apparatus with deionized water multiple times. All washing solutions were filtered through the 

same glass-fiber filter to minimize any sample loss due to adhesion of microplastics on the wall 

of any part of the filter apparatus. The microplastic isolation was repeated 3 times for each 

sample to ensure recovery. Since organic material was not a problem in the sand samples, no 

further processing was necessary to remove it during the density separation. The particles were 

Figure 1. Geographic distribution of the thirty-seven NPS sites sampled for microplastics. 

counted according to color and relative shape. For each NPS unit site, a blank consisting of the 

salt saline solution but with no sediment was run concurrently with the 4 samples to assess 

potential background contamination from the method or from the lab itself. These blanks had an 

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average of 2 pieces (SD = 1.5) of microplastics. 

To count and identify the shape of the microplastics, the filters were examined using an EMZ-5 

Meiji Binocular Stereoscope (0.7X-4.5X binocular zoom stereo body, W.D. 93mm). The entire 

filter was scanned thoroughly. Large pieces of vegetative debris such as seaweed and dry leaves 

were picked out with tweezers. A total of 185 filters were analyzed (37 sites, four samples from 

each site, and a blank for each site) using pre-set criteria such as no visible organic structures and 

clear homogeneous colors (Hidalgo-Ruz et al. 2012). The abundance of microplastics in a sand 

sample was expressed as the number of pieces per kg dry sand. 

2.3 Quantification of Urbanization Relative to Microplastic Distribution

To evaluate the potential relationship between urbanization and abundance of microplastics 

on coastal sites, total hectares of urban area within a 50-km diameter of each sampling site was 

quantified using Esri ArcMap 10.2 software (Esri Co. Ltd, USA). Land cover data were obtained 

from the National Oceanic and Atmospheric Administration’s Coastal Change Analysis Program 

(NOAA 2017). Hectares of urban area was determined by summing the hectares of high, medium 

and low intensity developed area as categorized by the land cover data. 

2.4 Wastewater Treatment Plants

About 80% of debris is estimated to come from urban land-based sources (Andrady 2011). Since 

most of the microplastics humans generate through their daily routine (i.e., brushing teeth, 

washing face) or washing clothes (allowing fibers to enter the system) could pass through a 

wastewater treatment system (WWTS), the proximity of the sampling location to a WWTS might 

explain levels of microplastics found. Distance to wastewater treatment plants was measured 

using the ArcGIS distance tool in Esri ArcMap 10.2 software (Esri Co. Ltd, USA). The shortest

distance via a water route between the sampling sites and the WWTS was recorded. Wastewater 

treatment plant locations were obtained from the Environmental Protection Agency’s Facility

Registry Service (US EPA 2015). 

2.5 Statistical Analysis

The summary statistics, graphs, and data analysis were generated using InfoStat statistical software, Version 2016 (Di Rienzo et al. 2016). Linear and non-linear regressions were preformed to

determine if a there was a relationship between the mean abundance of microplastics at a site and 

hectares of urbanization, distance to the nearest river, and distance to WWTS. Only linear regressions are shown because non-linear regressions failed to improve statistical relationships. Statistical comparisons between regions or individual parks was not done because the sampling design 

did not include sufficient independent samples within parks or enough sites within regions for 

robust statistical analysis. 

3. RESULTS

3.1 Sample Observations

Microplastics were found at all coastal sites but with variation between and within sites (Table 2;

Figures 2, 3). Apostle Island National Lakeshore (WI), National Park of American Samoa 

(American Samoa) and Kalaupapa National Historical Park (HI) had the highest abundances of 

microplastics averaging between 170 and 225 pieces of microplastics per kg of sand. Sites with 

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Table 2: Mean microplastic loads (pieces/kg of sand), standard error, minimum, maximum, 

and median value for the NPS unit. Quartile rank is based on mean microplastic abundance 

relative to the other parks. 

the lowest nc t t ona stor ca t ona

Monument (CA), Lake Clark National Park and Preserve (AK), Klondike Gold Rush National

Historical Park (AK) and Glacier Bay National Park and Preserve (AK), all of which had an 

average of less than 50 pieces per kg of sand. Samples from the other sites generally ranged from 

50 to 125 pieces per kg of sand. 

Region NPS Unit

Mean

count per

kg sand S.E. Min Max Median

Quartile

rank

Alaska 

ANIA 51.3 10.5 20 65 ` 0-25 

BELA 95.0 22.5 35 140 102.5 26-50 

CAKR 123.8 24.6 80 180 117.5 51-75 

GLBA 42.5 23.9 0 110 30 0-25 

KATM 128.8 36.1 75 235 102.5 51-75 

KEFJ 43.8 5.2 35 55 42.5 0-25 

KLGO 38.8 8.3 15 50 45 0-25 

LACL 40.0 12.1 20 75 32.5 0-25 

SITK 21.3 4.3 10 30 22.5 0-25 

WRST 97.5 25.3 55 155 90 26-50 

Great Lakes 

APIS 221.3 28.8 155 285 222.5 76-100 

GRPO 117.5 13.6 95 150 112.5 51-75 

INDU 152.5 7.8 130 165 157.5 76-100 

ISRO 88.8 8.0 65 100 95 26-50 

PIRO 65.0 5.4 55 80 62.5 26-50 

SLBE 156.3 29.9 105 235 142.5 76-100 

Northeast 

ACAD 126.3 43.2 30 235 120 76-100 

ASIS 112.5 15.1 80 145 112.5 51-75 

BOHA 100.0 6.5 85 115 100 51-75 

CACO 106.3 19.7 50 140 117.5 51-75 

FIIS 106.3 30.9 50 185 95 51-75 

GATE-JB 95.0 14.7 65 125 95 26-50 

GATE-SH 63.8 19.1 10 100 72.5 0-25 

GATE-SI 88.8 17.4 40 120 97.5 26-50 

West Coast 

CABR 38.8 7.2 30 60 32.5 0-25 

CHIS 56.3 10.5 35 85 52.5 0-25 

GOGA 140.0 24.8 100 210 125 76-100 

LEWI 87.5 17.0 60 130 80 26-50 

OLMY 115.0 29.0 40 180 120 51-75 

PORE 140.0 22.7 100 200 130 76-100 

REDW 98.8 14.8 70 140 92.5 51-75 

SAJH 67.5 18.3 40 120 55 26-50 

SAMO 80.0 15.1 40 110 85 26-50 

Pacific

Islands 

HALE 131.3 18.3 100 170 127.5 76-100 

HAVO 98.8 27.7 20 150 112.5 51-75 

KALA 171.3 37.8 105 265 157.5 76-100 

abundances i luded Si ka Na i l Hi i l Park (AK), Cabrillo Na i l

NPAS 187.5 22.4 145 245 180 76-100 

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Alaska Great Lakes Northeast Pacific Island West Coast

0

50

75

100

150

175

200

250

Fibers made up 97% of the microplastics counted, which is consistent with what other studies 

have found (e.g. Baldwin et al. 2016, Chow et al. 2016, Mathalon and Hill 2014, Stolte et al.

2015). Most of the fibers were translucent (47%) and blue (25%). While the majority of 

microplastic pieces were fibers, beads and fragments were also seen. Beads were observed at 6 

sites: Boston Harbor Islands National Recreation Area (MA), Acadia National Park (ME),

Cabrillo National Monument (CA), Haleakala National Park (HI), Indiana Dunes National

Lakeshore (IN) and Gateway National Recreation Area at Jamaica Bay (NY, NJ). Boston Harbor 

National Recreation Area had an average of 5 beads per kg of sand and Haleakala National Park 

had an average of 2 beads per kg of sand. The other 4 parks only had an average of 1 bead per kg 

of sand. Beads were not encountered in the Alaska region. This does not mean that they are not 

present, just that the sampling did not capture them. Small plastic fragments (not beads or fibers)

were seen at 15 of the parks scattered across the geographic distribution of NPS sites (Figure 4c).

Most of them averaged less than 1 piece per kg of sand. Two sites had an average of 2 pieces per 

kg of sand: Indiana Dunes National Lakeshore and Kalaupapa National Historical Park (HI). 

25

125

225

275 

mean abundance microplastic/kg san 

CAKR

BELA

KATM

KLGO

WRST

SITK

ANIA

KEFJ

GLBA

LACL

APIS 

INDUPIRO

SLBE

ISRO

GRPO

BOHA

ASIS

ACAD

FIIS

CACO

GATE JB

GATE SI

GATE SH

NSPA

KALA

HAVO

HALE

CHIS

SAJH

CABR

REDW

SAMO

OLYM

PORE

GOGA

LEWI 

Site 

Alaska Great Lakes Northeast Pacific Island West Coast 

Figure 2: Mean abundance of microplastics per kg of sand for thirty-seven NPS units sampled during 

2015 and 2016. Colors represent the region the park is located. Error bars represent standard error. 

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mean microplastic/kg sand 

Figure 3: Geographic distribution of mean microplastic abundance for NPS units by bins of 50 

pieces per kg of sand (by color). 

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A B C

Fi l f he 

D

i l ics seen duri l

E

f shoreli les. A

F

gure 4: Examp es o t types of m crop ast ng ana ysis o ne samp :

Dark and light microbead; B: white microbead (HALE); C: blue plastic piece with organic 

material (KALE); D: tangle of fibers (NPAS); E: fibers; F: Fibers and beads (BOHA). The black 

dotted lines are the grid lines on the filter paper, the blue arrows point to the microplastics, and 

the black line at the bottom right of each frame equals 0.5 mm. 

3.2 Environmental and Human Influences

Many studies state that plastic debris is highest closest to more urbanized areas (Barnes et al.

2005, Browne et al. 2015). It has also been stated that the majority of microplastics are the 

product of land-based human activity, with as much as 80% moving from land to ocean 

(Andrady 2011, Newman et al. 2015). This can come from mismanaged plastic waste (Jambeck 

et al. 2015) as well as wastewater treatment plants. We calculated the hectares of developed area 

around the sampling point to see if proximity to developed land correlated to the amount of 

microplastics on the beach. Unlike other studies (Chow et al. 2016), there was no relationship

between developed area and number of microplastic particles seen (Figure 5). Indeed, many sites 

in the study are very remote and far from urban centers but still have over 100 pieces per kg of

sand, especially in Alaska, along the northwest Pacific coastline, and the islands in the Pacific. 

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Figure 5: Linear regression of developed area (ha) in a 50km diameter buffer and mean 

abundance of microplastics per kg of sand (solid line) shows no relationship between 

urbanization and microplastic abundance (dashed line: 95% confidence interval). 

Wastewater treatment plants (WWTP) process household and industrial waste in many areas of

the US. While many systems also process storm runoff, they were designed to help remove solids 

and prevent them from entering downstream environments. They were not designed to remove 

small solids such as microplastics. There was no relationship between distance to the nearest

WWTP and the sample study sites in this study (Figure 6). 

Figure 6: Linear regression of distance to the nearest waste water treatment plant (WWTP) in

km and mean abundance of microplastics per kg of sand (solid line) shows no relationship

between distance to WWTP and microplastic abundance (dashed line: 95% confidence interval) 

Rivers also represent a potential source for microplastics. They drain both rural and urban areas, 

along with WWTP outflow. This material is taken downstream and released to estuaries and 

coastal systems, where the microplastics can be deposited on shorelines. Again, there was no 

relationship between the distance to the nearest upstream river and the amount of microplastics at 

a sampling location (Figure 7). 

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Figure 7: Linear regression of distance to the nearest river in km and mean abundance of 

microplastics per kg of sand (solid line) shows no relationship between (dashed line: 95% 

confidence interval). 

4. DISCUSSION

Microplastics were found at all 37 NPS sampling sites, with loads varying about 10-fold among 

sites (Figure 2). The high variation among sites is not surprising due to the variety of factors that

influence source and movement of debris and the heterogeneous and dynamic environment of

beaches. Additionally, material is likely continually being taken from and re-deposited onto the 

coastline at all sites to varying degrees. Among-site variation has been shown to be high in large 

marine litter found along the coastline, both temporally and spatially (Browne et al. 2011, 

Browne et al. 2015). There is no reason to think that microplastics would be any different;

however, local spatial and temporal patterns have not been examined much in the literature. This 

study was not intended to quantify within site variation, but to give a broad snapshot of what 

might be found on a typical day along US NPS coasts. This sampling scheme was developed to 

allow for a broad geographic view of the distribution of microplastics along US coastlines which 

will lead to a better understanding of the overall distribution of this debris and what factors may 

influence distribution. It is important to remember that sampling was targeted to beaches within

each National park that were known to accumulate large marine debris. 

Even though differences in methodologies make comparisons with other studies challenging, the 

microplastic quantities observed in this study did fall within the global range reviewed in Van 

Cauwenberghe et al. (2015; see also Stolte et al. 2015, Lusher 2015). This study found lower 

levels of microplastic loads than a study in the Southeast US, where some sites at the base of

large rivers and samples from the Virgin Islands averaged over 300 pieces per kg of sand (Chow 

et al. 2016). Consistent with many studies, fibers were the most common microplastics 

(Claessens et al. 2011, Stolte et al. 2015). Every color of fiber was seen, but most of our fibers 

were translucent or blue. This was consistent with a study from Taiwan (Kunz et al. 2016) and 

the German Baltic (Stolte et al. 2015) but not with the SE US study, which saw predominately

blue fibers and not many translucent ones (Chow et al. 2016). As fibers are exposed to oxidative 

stress from the sun, they tend to bleach out and disintegrate (Stolte et al. 2015, Andrady 2016). It 

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is possible more fibers in this study were in the environment longer than those in the SE study. 

The chemical composition of the fibers was not determined; however, the density separation 

method used maximizes separation of microplastics from sand. Even if the fibers were not plastic

(i.e. cotton or rayon), they could potentially pose threats to the environment (Remy et al. 2015). 

4.1 Human influences

It is challenging to determine the source of anthropogenic microplastics. Studies state that as 

much as 80% of microplastics come from urban, land-based sources (Andrady 2011, Newman et 

al. 2014, Browne 2015, Yonkos et al. 2014). For the sites in this study, there was no relationship

between microplastic load and the amount of urbanized area. This seems generally surprising 

based on known sources of microplastics. Even though many of the NPS sites are remote, some 

still have midrange counts of microplastics relative to other sites in this study (like Bering Land 

Bridge National Preserve in Alaska and Pictured Rocks National Lakeshore in Michigan). Other 

studies have failed to observe a relationship with urban development and microplastic loads. For 

example, in a study of tributaries in the Great Lakes region there was no relationship between 

microplastic loads and proximity of the sites to urban area (Baldwin et al. 2016). The large 

geographic area sampled here contains sites with so many different geographic influences that

local factors may over-ride generally expected patterns, such as increased microplastic loads with 

amount of urban area. Factors such as local currents or whether sites are on islands may have a 

greater influence on the presence of microplastics than urbanization. 

Since most areas had WWTPs that process household waste (and some process stormwater as 

well), they were hypothesized to be a potential source of microplastic particles to rivers, estuaries 

and eventually ocean environments (Browne et al. 2015), however, the distance to wastewater 

treatment plants did not help explain the microplastic loads on the beaches. In the last few years, 

more studies have analyzed WWTP outflow directly, with mixed results. In the Great Lakes and 

California, WWTP’s direct contributions were low (Baldwin et al. 2016, Carr et al. 2016, Mason 

et al. 2016) all averaging between 0.5 and 1.4 microplastic pieces per liter of outflow. 

Interestingly, these studies reached different conclusions on the microplastic contributions 

WWTP make. Carr et al. (2016) concluded that WWTPs were very effective at removing 

microplastic contaminants while Mason et al. (2016) suggested that they were responsible for an 

average of 13 billion microplastic particles being released into downstream systems every day. In

New Jersey, WWTPs were a source for primary microplastics, but not the only source since 

background sites also had microplastics (Estahbanati and Fahrenfeld 2016). This suggests that 

other sources, like runoff, were important as well. While most parks studied were within 75 km 

of a WWTP (Figure 6), their locations were still fairly remote and the communities they serve 

were generally smaller as shown by the low amount of urban area nearby (Figure 5). 

The issue of WWTP contribution to microplastic pollution is complicated and can vary from site

to site depending on the age of facility, the stages of processing used, and the size of filters used 

at each location. While WWTPs seem to be effective at removing microplastic particles, some 

still pass through. Where sludge from WWTP settling tanks is applied to agricultural fields, it 

could subsequently contribute to microplastic pollution during overland flow and runoff (Mahon 

et al. 2017), creating another level of complexity to understanding microplastic sources. Like 

WWTP, septic tanks collect household waste. In rural areas, which are often far from WWTP, 

septic tanks are more common. Release of microplastics from septic systems could be significant 

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in times of high runoff or flooding events and deserves more research.
	

Distance to the nearest upstream river was analyzed because rivers carry microplastics (Rech et 

al. 2014) from overland flow, discharge from WWTP, or from septic tanks during flooding. 

While high levels of microplastics have been seen in rivers and estuary systems (Mathalon and 

Hill 2014, Moore et al. 2011, Baldwin et al. 2016, Ballent et al. 2016), no relationship between 

the distance to the nearest river and microplastic load was found for the NPS sites (Figure 7).

These findings were not surprising since there was a broad range of sites with many potential 

contributing factors, such as differences in location of sampling site (bay side versus directly on 

the ocean), river flow rates, shape of the sample-location estuary or shoreline that might

influence accumulation or export of materials, ocean currents, WWTP processing, etc. 

4.2 Local influences of Microplastics

Microplastic loads on shorelines come from either land-based sources such as rivers and 

wastewater treatment plants, or from the degradation of larger plastic pieces in the open ocean 

landing on the shore. Many studies have examined the amount of microplastics floating in the 

ocean, with amounts estimated from 93,000-236,000 metric tons, with most plastic being 

concentrated in the subtropical gyres (van Sebille et al. 2015). While models differed on the total 

amount of microplastics (Cozar et al. 2014), they all found the largest mass in the North Pacific

Ocean while the North Atlantic had between 7-10% of what was found in the North Pacific (van 

Sebille et al. 2015, Kanhai et al. 2017). This difference was attributed to the amount of 

mismanaged waste estimated to enter coastal waters from Asia (Jambeck et al. 2015). 

Storms often intensify the action of currents, waves, and tides and increase outflow from rivers 

(Yonkos et al. 2015). They bring increased winds and wave action that result in erosion and/or 

deposition of beach material – including microplastic particles. This study did not examine the 

impact of storms on the abundance of microplastics on beaches, but 14 of the 37 sites sampled 

reported a storm sometime during the two 

weeks prior to the sample being taken. The 

beaches with storms were distributed across 

the geographic range. Of the 14 sites with 

storms, 3 of sites had high levels of 

microplastics (Apostle Islands National

Lakeshore (WI), Indiana Dunes National

Lakeshore (IN), Haleakala National Park 

(HI)) while 3 sites had some of the lowest

levels of microplastics (Cabrillo National

Monument (CA), Kenai Fjords National Park 

(AK), and Gateway National Recreation Area 

at Sandy Hook (NY, NJ)). While storms 

might influence the amount of microplastics 

found, repeated sampling at various sites 

after a series of storms would be needed to

understand this question. 

Region NPS Unit

Mean count

per kg sand

Quartile

rank

Alaska KEFJ 43.8 0-25 

Great

Lakes

PIRO 65.0 26-50 

ISRO 88.8 26-50 

GRPO 117.5 51-75 

INDU 152.5 76-100 

APIS 221.3 76-100 

Northeast

GATE-SH 63.8 0-25 

GATE-JB 95.0 26-50 

FIIS 106.3 51-75 

West Coast CABR 38.8 0-25 

REDW 98.8 51-75 

Pacific

Islands

HAVO 98.8 51-75 

HALE 131.3 76-100 

Table 3: Sites with storms reported in the two 

weeks prior to sampling listed in order of

increasing mean microplastic abundance 

within each region. 

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Pacific Islands 

Hawaii is located at the convergence zone in the middle of the North Pacific Ocean (NOAA 

2017) and close to the Pacific gyres where both wind and currents in the area will push floating 

microplastics to shore. Indeed, some of the highest microplastic loads were found in the 

Hawaiian Islands. Both Kalaupapa National Historical Park, located on the island of Molokai,

and Haleakala National Park, located on the island of Maui, receive direct winds from the east

(Xie et al. 2001), which could bring floating microplastics from these gyres onshore. In addition, 

there was a drain pipe that empties onto the beach within sight of the sampling location at

Haleakala National Park (Personal Communication, 2015 J. Herbaugh, Park Ranger). This could 

carry more land-based material to the beach. The subtropical countercurrent that runs from the 

western Pacific toward Hawaii (Xie et al. 2001) could carry debris directly from the Asian coast.

Hawai’i Volcanoes National Park had the lowest microplastic load of the three Hawaiian sites 

(but still in the top half of all sites in this study). Its location on the leeward (south) side of the 

island of Hawaii reduces onshore winds and places it near a current that pushes water away from 

shore (Xie et al. 2001), potentially reducing the microplastic load at that site. 

National Park of American Samoa is the only US National park in the Southern hemisphere, 

located on the island of Tutuila. Tutuila has very steep slopes and very little flat coastal area 

(only 26 km2

) for 66,900 people and tourists. Winds are typically light, except during storms, but 

rain can be heavy. The steep slopes and increasing pressure from a growing population combined 

with heavy rains resulted in runoff into the bays and coral reefs surrounding the island (Fenner et 

al. 2008). They reported that the average sedimentation rate was 12.1 g/cm2

/day into the bays. 

This input could be carrying microplastics from failed septic systems and other household or 

industrial discharge. Most marine debris on the island was from land based anthropogenic

sources and not the ocean (Fenner et al. 2008). Thus, it is likely that most of the microplastic

load we found at this site was from land and not the open ocean. 

West Coast

Farther to the east in the Pacific, toward the US West Coast, there was less microplastic debris 

along the coastal areas (Law et al. 2014). The California Current moves south and offshore along 

the coast and is dominated by upwelling of deep ocean water (Personal Communication, A. 

MacFadyen, Physical Oceanographer, 6 March 2017). It was not surprising that the microplastic

load found along the west coast was in the midlevel range in this study (Table 2, Figure 3) as 

ocean dynamics would counteract land-based sources. Sites that did have moderate to high levels 

of microplastics were probably receiving it from land-based sources. For example, Golden Gate

National Recreation Area, which had one of the highest microplastic loads in the region, likely

got most of it from the San Francisco Bay area, which is densely populated and drains much of

the agricultural area of California. Olympic National Park, which had similar levels of 

microplastics as Golden Gate National Recreation Area, could get contributions from both the 

ocean and from the Strait of Juan de Fuca, which is downstream of Seattle, Washington. Olympic

National Park is at the northern end of the California current, potentially allowing more 

contributions from the ocean to reach the shoreline before upwelling carries it away. 

Alaska 

In general, Alaska had very low microplastic loads, even though the sites were known to receive 

large marine debris. For most of Alaska, previous modeling work found very little plastic in 

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coastal waters (Law et al. 2014). Law et al. (2014) predicted there could be about 10,000 plastic 

pieces per km2 in the Bering Strait and around Cook Inlet, which is near both Katmai National

Park & Preserve and Aniakchak National Monument & Preserve. It is possible that some of this 

oceanic microplastic made it to Katmai National Park & Preserve beach. The predicted levels in

the Bering Strait, which flows up to Bering Land Bridge National Preserve and Cape 

Krusenstern National Monument, could have also carried some to those shorelines as well. Both 

of these sites had moderate levels of microplastic counts (Table 2, Figure 3). 

Atlantic Ocean 

While the Atlantic Ocean reportedly had fewer floating microplastics (Law et al. 2010, van 

Sebille et al. 2015, Kanhai et al. 2017), it could still serve as a source for microplastics found on 

the East Coast. The Gulf Stream is the predominant current; however, it turns offshore around the 

Virginia–North Carolina state line (Rowe et al. 2017). The currents to the northwest of the Gulf

Stream are less obvious but generally appear to head away from the coast (Gyory et al. 2017).

This would tend to push microplastics away from the shoreline unless a prevailing wind carried 

it ashore. The coastal sites with high levels of microplastic loads were in estuary systems, such as 

Acadia National Park (ME) and Boston Harbor Islands National Recreation Area (MA).

Surprisingly, the Gateway National Recreation Area parks (NY, NJ) were not as high given their 

proximity to New York City and locations within the Hudson River estuary. 

Great Lakes

The Great Lakes had relatively high levels of microplastics in surface waters (Eriksen et al.

2013) as well as its tributaries (Baldwin et al. 2016, Ballent et al. 2016), but surface water 

microplastic abundance was variable. Lake Superior had as much as 12,645 pieces per km2 

(Eriksen et al. 2013). The lake has long turnover rates, which could allow microplastics to 

remain for long periods. The NPS sites in Lake Superior had some of the highest microplastic

loads in the entire study (such as Apostle Islands National Lakeshore; Table 2). Most 

microplastics entered the Great Lakes via its tributaries (Baldwin et al. 2017, Ballent et al. 2016).

This would explain the high counts at Apostle Islands National Lakeshore, which is located near 

the mouth of the St. Louis River. This river runs through Duluth, MN, and is the largest tributary 

of the lake with a 3,584-square-mile watershed. Strong currents that move from Duluth eastward 

toward the Apostle Islands, along with complicated wave action around the islands (Bai et al.

2013, Beletskey et al. 1999), would increase the probability of elevated microplastic loads. 

Pictured Rocks, a park at the other end of Lake Superior, had one of the lowest levels of 

microplastics in the Great Lakes. This park had very little developed land nearby and all the 

watersheds for this park flow south into Lake Michigan. Thus, most of the microplastic load here 

was probably transported from other areas of Lake Superior, but this transport was likely limited 

by being on the lee side of the Keweenaw Peninsula that sticks out into the lake between Apostle

Islands National Lakeshore and Pictured Rocks National Lakeshore (Bai et al. 2013). 

There are strong currents and long residence times for the waters of Lake Michigan as well. At

the south end of the lake there is a strong counterclockwise coastal current that travels from 

Wisconsin to Muskegon, MI creating a rotating gyre in the southern basin of Lake Michigan that

traps chlorophyll a (Kerfoot et al. 2008). This water movement could also trap microplastics in

the southern basin of the lake, increasing the opportunities for the microplastics to be blown to

the shores of parks on the east side of Lake Michigan such as Indiana Dunes (Bai et al. 2013). 

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The Great Lakes region was likely influenced by run-off as well. Neither our study nor Baldwin 

et al (2016) found relationships between the counts of microplastics and urban area or WWTP 

contribution. Baldwin et al. suggested that overland flow was a likely culprit of the levels of 

microplastic in tributaries. Sewage sludge that traps most of the microplastics from household 

waste is often applied to agricultural fields. Thus, during precipitation events, microplastics in 

applied sludge can run-off to downstream environments. The agriculturally-dominated landscape 

around the lakes increases the opportunity for this to be a microplastic source. Since much of the 

area is undeveloped, septic tank overflow during times of high flow events could also contribute. 

Potential Threats

Plastic is known to absorb environmental contaminants, such as PCBs, and potentially transport

them to other locations. It has been shown that both persistent organic pollutants and heavy 

metals adsorb to plastic (Brennecke et al. 2016). Microplastics have a large surface area relative 

to their overall size, allowing them to carry a greater amount of contaminant. Their small size 

allows smaller organisms to ingest them, increasing their risk of exposure as well as facilitating 

bioaccumulation in organisms higher in the food chain (Setala et al. 2014, Avio et al. 2015).

Some of the threats to organisms exposed to microplastics with contaminants are blockages and 

abrasions of the digestive tract, satiation, and eventual starvation due to consumption of non-prey 

items, which can lead to reduced reproductive fitness and predator avoidance (Wright et al. 2013, 

Avio et al. 2015). Browne et al. (2013) found that plastic and contaminants harm the 

physiological functions of marine sedimentary organisms. They saw the desorption of 

contaminants directly from the plastic in the gut, as well as from sand. This could lead to not 

only organismal level effects but population level effects and changes in ecosystem dynamics. 

More recently Koelmans et al. (2016) tested the hypothesis that microplastics would transfer 

hydrophobic organic chemicals to marine animals. They found that while there was some 

transfer to animals, the plastizers in the plastic were more harmful than the organic chemicals

bound to the plastics. They also found that the fraction of contaminant in the plastic was small

compared to the nearby water or sediment. While they demonstrated that contaminants desorbed 

from microplastic in the presence of gut fluid, they concluded that microplastic ingestion was not

likely to increase exposure because the surrounding environment had a higher concentration of 

contaminants than the microplastics (Kolemans et al. 2016). Understanding how wildlife and 

humans will be impacted by microplastic ingestion is a priority but was not examined in this 

study. 

4.3 Summary

The presence of microplastics in the marine environment poses risks to wildlife and human 

health. Not only is ingestion of plastic itself a concern, the potential contamination enhances that 

risk. These 35 units of the National Park System located on the Atlantic and Pacific oceans and 

Great Lakes include diverse coastal environments to evaluate factors affecting the distribution of 

microplastics. Microplastic contamination was widespread and found at even the remotest areas, 

which is not completely surprising given their global distribution (e.g., Thompson 2015).

Microplastic loads among National parks were quite variable, with the highest loads recorded in

individual parks in the Great Lakes and the Pacific Islands. Many sites in the study were far from 

urban centers but still had over 100 pieces per kg of sand, especially in Alaska, along the 

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northwest Pacific coastline, and the islands in the Pacific. However, no clear relationship to

geographical features was apparent. This was not completely unexpected given the broad 

geographic sampling scale and the numerous local factors that could influence microplastic

abundance along these shorelines. Understanding the spatial and temporal movement and 

residence time of microplastics in beach environments will clarify the risk to wildlife in the 

future. 

This study provides a broad geographic assessment of the distribution and abundance of 

microplastics on NPS beaches and provides an opportunity to make general inferences about

sources. Because of this diverse geography and oceanography, the coastal parks have served an 

important role in advancing landscape and seascape-scale research on many issues affecting 

stewardship of public lands and waters. NPS scientists and managers will use this study in 

concert with other research to evaluate patterns of microplastic loadings in parks and regions 

where parks are located. This information will guide further investigations with partner agencies 

and academic institutions. In addition, NPS will communicate the results of this project to the 

public to expand understanding of microplastic's contribution to marine debris, and marine debris

issues in the coastal environment in general. 

ACKNOWLEDGEMENTS

I would like to thank the National Park Service regional directors who coordinated sampling 

efforts in the parks as well as NPS employees and volunteers who collected samples. The Pate

Partner Program supported involvement of two undergraduates on the project, E’Neysia Denny 

and Tyler Pyatt. E’Neysia helped with putting the sampling boxes together and creating sampling 

protocol and training videos. Tyler Pyatt helped create training videos as well as processed the 

samples in the lab. Brian Williams and Jeff Vernon assisted with GIS. I would like to thank the 

following NOAA personal: Eric Anderson from the NOAA’s Great Lakes Environmental

Research Laboratory for help with understanding currents in the Great Lakes; Matthew Coomer 

assisted with information about the Waste Water Treatment Plants; Amy MacFadyen, Glen 

Watabayashi, and Jordan Stout for help understanding large ocean currents. I would also like to

thank Sarah Latshaw, Carlie Herring, Sherry Lippiatt, and Amy Uhrin for guidance during the 

duration of the project and comments on previous versions of the report. 

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Supplement A
 

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Supplement B

Table B1: Microplastic loads (pieces/kg of sand), standard error, minimum and maximum value 

for the site, urban area (ha) in a 50km diameter buffer, distance to waste water treatment plant

(WWTP) in km, distance to nearest river (km). 

Region NPS Unit

Mean

count per

kg sand S.E. Min Max Median

Urban

Area (ha)

distance to

WWTP

(km)

distance

to river

(km)

Alaska 

ANIA 51.3 10.5 20 65 60 0.0 555.7 9.2 

BELA 95.0 22.5 35 140 102.5 21.5 0.4 23.8 

CAKR 123.8 24.6 80 180 117.5 0.0 18.0 45.4 

GLBA 42.5 23.9 0 110 30 378.0 0.7 1.5 

KATM 128.8 36.1 75 235 102.5 0.0 198.9 4.1 

KEFJ 43.8 5.2 35 55 42.5 0.0 268.4 3.5 

KLGO 38.8 8.3 15 50 45 289.2 6.0 2.1 

LACL 40.0 12.1 20 75 32.5 0.0 5.1 

SITK 21.3 4.3 10 30 22.5 704.4 2.7 14.8 

WRST 97.5 25.3 55 155 90 0.0 502.7 43.6 

Midwest 

APIS 221.3 28.8 155 285 222.5 800.6 21.1 7.8 

GRPO 117.5 13.6 95 150 112.5 0.9 57.1 7.6 

INDU 152.5 7.8 130 165 157.5 17459.0 3.1 2.4 

ISRO 88.8 8.0 65 100 95 0.8 104.1 0.4 

PIRO 65.0 5.4 55 80 62.5 277.5 119.0 

SLBE 156.3 29.9 105 235 142.5 3588.5 92.8 0.3 

Northeast 

ACAD 126.3 43.2 30 235 120 3592.5 13.4 24.9 

ASIS 112.5 15.1 80 145 112.5 7130.6 12.9 6.0 

BOHA 100.0 6.5 85 115 100 73669.4 3.3 3.1 

CACO 106.3 19.7 50 140 117.5 3790.0 59.1 59.1 

FIIS 106.3 30.9 50 185 95 52007.6 78.9 

GATE-JB 95.0 14.7 65 125 95 50539.7 17.4 10.1 

GATE-SH 63.8 19.1 10 100 72.5 42901.0 13.1 16.2 

GATE-SI 88.8 17.4 40 120 97.5 72987.7 10.3 17.0 

West Coast 

CABR 38.8 7.2 30 60 32.5 46214.6 0.3 3.7 

CHIS 56.3 10.5 35 85 52.5 4.3 63.7 

GOGA 140.0 24.8 100 210 125 30053.7 0.9 6.4 

LEWI 87.5 17.0 60 130 80 3639.2 42.0 19.9 

OLMY 115.0 29.0 40 180 120 231.1 37.2 14.6 

PORE 140.0 22.7 100 200 130 556.3 52.4 2.6 

REDW 98.8 14.8 70 140 92.5 345.2 51.1 1.3 

SAJH 67.5 18.3 40 120 55 2318.6 10.5 6.6 

SAMO 80.0 15.1 40 110 85 57043.0 17.7 0.5 

Pacific

Islands 

HALE 131.3 18.3 100 170 127.5 524.4 52.5 0.7 

HAVO 98.8 27.7 20 150 112.5 616.0 88.3 9.0 

KALA 171.3 37.8 105 265 157.5 1017.1 70.5 

NPAS 187.5 22.4 145 245 180 1641.9 36.4 0.2 

25
	
 

 

 

 

 

 

 

 

 

Table B2: Mean abundance of plastic pieces per sample that were greater than 4.75 mm and 

mean abundance of microplastic pieces per sample that were 2.0-4.75 mm. 

Region NPS Unit

Mean count

per kg sand

(<2.0 mm)

Mean count

2.0-4.75 mm

per sample

Mean count

>4.75 mm per

sample

Alaska 

ANIA 51.3 

BELA 95.0 

CAKR 123.8 

GLBA 42.5 

KATM 128.8 

KEFJ 43.8 

KLGO 38.8 

LACL 40.0 

SITK 21.3 

WRST 97.5 

Great

Lakes 

APIS 221.3 

GRPO 117.5 

INDU 152.5 

ISRO 88.8 

PIRO 65.0 

SLBE 156.3 

Northeast 

ACAD 126.3 

ASIS 112.5 0.1 

BOHA 100.0 0.1 

CACO 106.3 

FIIS 106.3 

GATE-JB 95.0 

GATE-SH 63.8 0.1 

GATE-SI 88.8 

West Coast 

CABR 38.8 

CHIS 56.3 

GOGA 140.0 

LEWI 87.5 

OLMY 115.0 

PORE 140.0 

REDW 98.8 

SAJH 67.5 

SAMO 80.0 0.2 

Pacific

Islands 

HALE 131.3 

HAVO 98.8 

KALA 171.3 3.3 0.7 

NPAS 187.5 0.7 

26 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table B3: Data entered on data sheet from each NPS unit. Large debris was defined as larger 

than a soccer ball and amount was categorized as 1, 2-5, 6-10, or 11+ (Supplement A). Not all

parks recorded the type of large debris seen. If the park conducted regular cleanups, the date of

last cleanup was also reported. 

Region NPS Unit

Date

Sampled

Large

debris in

view of

sample site

Number

of large

debris

items

Type of

large

debris

Is there

regular

beach

cleanup?

Date of last

cleanup

Alaska 

ANIA 5/9/2016 Yes 11+ Fishing 

line,

bouys 

BELA 5/27/2016 No No 

CAKR 7/9/2015 Yes 1 No 

GLBA 7/16/2015 No No 

KATM 7/19/2015 Yes 1 1x/year June 2015 

KEFJ 7/30/2015 Yes 2-5 Yearly May2015 

KLGO 10/6/2015 No No 

LACL 7/5/2016 No No 

SITK 8/3/2015 No No 

WRST 6/19/2015 Yes 6-10 No One time only

early June

2015 

Great

Lakes 

APIS 7/1/2015 No Yes N/A 

GRPO 6/29/2015 Yes 11+ Weekly 6/15/15 

INDU 6/24/2015 Yes 1 No 

ISRO 7/21/2015 No No 

PIRO 8/7/2015 No No 2005 

SLBE 7/10/2015 Yes 1 Large logs 1x/week 7/5/15 

Northeast 

ACAD 7/17/2015 No 

ASIS 7/16/2015 No No April 2015 

BOHA 7/16/2015 Yes 2-5 Plastic

and glass 

A few 

times/year 

7/16/2015 

CACO 8/3/2015 No No 

FIIS 7/13/2015 Yes Balloons,

bouys 

No 

GATE-JB 7/8/2015 Yes 6-10 No 

GATE-SH 7/16/2015 Yes 2-5 No 

GATE-SI 7/7/2015 Yes 2-5 2x/season Unknown 

West

Coast 

CABR 10/15/2015 No 1-2x/mo 

during OctApril 

10/11/2015 

CHIS 7/6/2015 No No 

GOGA 8/27/2015 No Every 28

days 

7/29/2015 

LEWI 7/31/2015 No Quarterly June 2015 

OLMY 7/17/2015 No yearly unknown 

27 
 

 

 

 

 

 

 

 

 

PORE 7/15/2015 No No 

REDW 9/1/2015 No No 

SAJH 7/21/2015 No No 

SAMO 12/7/2015 Yes 2-5 

Pacific

Islands 

HALE 7/17/2015 No 

HAVO 10/30/2015 No 

KALA 7/1/2015 Yes 2-5 

NPAS 7/15/2015 Yes 6-10 

/2015 

Concrete

blocks 

unknown unknown 

No 

No 

quarterly June 2015 

Glass,

wood, 

tires, cans,

plastic

bottles 

No 

7/20

28