2013 Probabilistic Streams Survey in Puerto Rico
b/xi/ {*\
Report prepared by: James Kurtenbach, Aquatic Biologist
Monitoring Operations Section
Approved by: Randy Firaun, Acting Chief
MonitqjHng and Assessment Branch
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TABLE OF CONTENTS
LIST OF FIGURES ii
LIST OF ACRONYMS iii
EXECUTIVE SUMMARY iv
1.0 INTRODUCTION 1
2.0 METHODS 2
2.1 Survey design 2
2.2 Study area 2
2.3 Sample parameters and collection 3
2.4 Setting thresholds 4
3.0 RESULTS OF THE CONDITION OF PUERTO RICO'S STREAMS 5
3.1 Biological indicator 6
3.2 Development of a multimetric index of biological integrity 6
3.3 Findings for the Mil of biological condition 7
3.4 Chemical indicators of stress 8
3.4.1 Phosphorus 8
3.4.2 Nitrogen 9
3.4.3 Chloride 10
3.4.4 Dissolved oxygen 11
3.5 Physical habitat indicators of stress 12
3.5.1 Streambed sediments (% sand and % embeddedness) 13
3.5.2 Riparian vegetative cover 15
3.5.3 Fish habitat condition 15
3.5.4 Riparian disturbance 16
3.6 Ranking of stressors 17
3.7 Changes in stream condition 18
4.0 DISCUSSION AND MANAGEMENT IMPLICATIONS OF FINDINGS _ 20
4.1 Summary 20
4.2 Future direction 22
LITERATURE CITED 25
APPENDIXES
A STREAM SITES AND LOCATIONS
B THRESHOLDS FOR BIOLOGICAL, CHEMICAL AND PHYSICAL
HABITAT INDICATORS
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List of Figures
1. Map of stream sites in Puerto Rico 3
2. Biological condition of streams based on the Mil 7
3. Total phosphorus concentrations in Puerto Rico streams 9
4. Total nitrogen concentrations in Puerto Rico streams 10
5. Chloride concentrations in Puerto Rico streams 11
6. Dissolved oxygen conditions in Puerto Rico streams 12
7. Sediment (percent sand) levels in Puerto Rico streams 13
8. Sediment (percent embeddedness) levels in Puerto Rico streams 14
9. Riparian vegetative cover in Puerto Rico streams 15
10. In-stream fish habitat in Puerto Rico streams 16
11. Riparian disturbance in Puerto Rico streams 17
12. Extent of stressors 18
13. Change in macro invertebrate condition between 2009 and 2013 19
14. Change in chemical and habitat indicator condition between 2009 and 2013 20
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List of Acronyms
EPA
Environmental Protection Agency
GIS
Geographical Information System
GLEC
Great Lakes Environmental Center
IBI
Index of Biological Integrity
Mg/1
milligrams per liter
Mil
M aero in vert cbr at e Integrity Index
NaCl
sodium chloride
NHD
National Hydrography Dataset
PR
Puerto Rico
PREQB
Puerto Rico Environmental Quality Board
TN
total nitrogen
TP
total phosphorus
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EXECUTIVE SUMMARY
Aquatic resources in the United States and Puerto Rico are threatened by continued
degradation caused by numerous anthropogenic stressors. Under the Clean Water Act,
States, US Territories, and Commonwealths are required to measure status and trends of
surface water quality and determine the extent to which waterbodies support healthy
aquatic ecosystems. To date, this has been largely accomplished through programs
designed to routinely monitor waterbodies for various chemical, physical, and biological
parameters. However, as with the streams and rivers in the United States, there has
generally been a lack of consistent and comprehensive water monitoring and reporting of
results in Puerto Rico. In fact, typical State targeted monitoring networks have been
criticized for their lack of design to make statistically valid inferences about water quality
(e.g., estimates of good, fair, and poor). This survey provides the second of two
statistically valid assessments of biological condition, including key chemical and
physical habitat indicators of stress, across streams in Puerto Rico. Specifically, this
report describes the estimates of stream biological condition using benthic
macroinvertebrates, and the identity and rank of chemical and physical stressors affecting
stream condition. In addition, estimates of change between the current and 2009 survey
are given.
This study encompassed wadeable streams in watersheds located throughout the
mountain interior of Puerto Rico, which are characterized by moderate to steep gradient
and represent the majority of river miles in Puerto Rico. A statistical design used to
select the sites ensured representative sampling and provided an unbiased estimate of
chemical, physical, and biological condition. In 2009, 50 stream sites were assessed
using consistent field methods for biological, water quality, and physical habitat.
Twenty-two of these stream sites were revisited in 2013.
Using a macro invertebrate indicator of bio logical condition, 42% (1,219 miles), 34%
(987 miles), and 24% (697 miles) of Puerto Rico's stream length is in good, fair, and
poor condition, respectively as compared to the least-disturbed reference condition
established in Puerto Rico. The 42% stream length shown to be in good condition is
considered to be representative of a range of expected values for least-disturbed reference
condition in Puerto Rico.
Results of the survey also show the current extent of stressors across Puerto Rico. The
most common stressors for stream length in Puerto Rico are the loss in complexity of the
riparian vegetation and impaired fish habitat. Fifty percent of the stream length (1,451
miles) was determined to be poor for these indicators of physical habitat. Stressors
ranking poor for intermediate length of streams in Puerto Rico, included nutrients (TN
and TP), and habitat indicators of riparian disturbance and stream sediment. The least
common stressors of the stream length in poor condition in Puerto Rico, were chloride
10% (290 miles) and dissolved oxygen 0%.
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Comparing the changes from the previous 2009 survey, several of the chemical and
habitat indicators were determined to be statistically significantly different. No
statistically significant change in the percentage of good macro invertebrate integrity
index (Mil) scores was noted between the reporting periods 2009 and 2013, A
statistically significant decrease in stream miles in good condition for phosphorus was
detected in the 2013 survey. Between 2009 and 2013 this difference was 12%. For two
of the habitat indicators, between the period 2009 and 2013, riparian vegetative cover and
percent embeddedness both had a statistically significant increase of stream miles in good
condition. Each indicator increased by 22% and 26%, respectively.
Understanding the current condition of streams is essential for effective decision making
in water programs to restore and maintain water quality. This survey was able to achieve
three desired objectives: (1) determine the percent of the streams in Puerto Rico in good,
fair, and poor condition for key indicators of ecological health and human influence; (2)
identity and rank what is the relative importance of key chemical and physical habitat
stressors; and (3) identify changes between the survey periods 2009-2013. The survey
results provide a solid baseline for future surveys to assess changes and detect trends in
stream condition over time. Also, data collected from the Puerto Rico streams survey can
be used in conjunction with other water quality data acquired by the Puerto Rico
Environmental Quality Board (PREQB) and assist them in water resource decision-
making and fulfill their requirements to report to EPA on the current condition of water
quality.
Additional research is essential to enhance the scientific rigor of stream assessments
conducted in Puerto Rico. Unlike temperate North America, few studies on Caribbean
streams have demonstrated regional-scale relationships between biological condition and
the severity of chemical and physical habitat stressors.
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1.0 Introduction
Puerto Rico has an abundance of streams that originate in the Luquillo, Cayey and
Central Cordillera Mountains, which flow across interior regions to the coastal plain and
empty into the Atlantic Ocean and Caribbean Sea. Despite having a relatively small land
area, Puerto Rico because of significant rainfall and steep topography, has greater than
1000 small streams. From these smaller catch basins, approximately 20 true river
systems are formed.
Aquatic resources in Puerto Rico are threatened by continued degradation caused by
numerous anthropogenic stressors. Human population growth on Puerto Rico has
increased by 86% since 1940 and was at 3.5 million people in 1990, and currently stands
at 3.7 million. Expanding human population, rapid economic development and lags in
infrastructure and pollution control have resulted in a water quality crisis. Water
pollution represents one of the most significant environmental problems in Puerto Rico
(Hunter and Arbona, 1995). Streams in Puerto Rico face significant ecological risks from
improperly treated sewage, landfill contaminants, agriculture, water diversions, extensive
land conversion and deforestation.
Like many streams and rivers in the continental United States, there has generally been a
lack of consistent and comprehensive water monitoring and reporting of results in Puerto
Rico. Also, typical State targeted monitoring networks have been criticized for their
biased assessment of environmental conditions and lack of a probabilistic survey design
that provides a statistical valid estimate of environmental conditions with known levels of
confidence (USGAO, 2000). In addition to survey design problems, an extensive
assessment of biological conditions using a direct measure of aquatic life in Puerto Rico
was not available. However, the first nationally consistent and statistically valid
assessments of streams and rivers were conducted in the United States (USEPA 2006,
USEPA 2011). These surveys provided the first ever statistically valid assessments of
biological condition, including key chemical and physical habitat indicators of stress,
across streams in the United States. The surveys have provided water resource managers
a better understanding of the current conditions of streams within broad geographic
regions and throughout the United States. The outcomes and successes of these surveys
prompted USEPA Region 2, in collaboration with the Puerto Rico Environmental Quality
Board (PREQB), to design and perform a similar assessment of wadeable streams in
Puerto Rico in 2009. This first probabilistic survey was designed to establish the baseline
environmental conditions of wadeable streams across Puerto Rico. Chemical, physical
habitat, and biological data were collected to determine the biological conditions and the
primary stressors responsible for impairments.
This report discusses the results of the 2013 survey and changes in key aquatic indicators
that have occurred since 2009.
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The survey had four objectives: (1) determine what percent of the streams in Puerto Rico
are in good, fair, and poor condition for key indicators of ecological health and human
influence; (2) identify and rank what is the relative importance of key chemical and
physical stressors. (3) identify changes between survey periods 2009-2013, and (4)
enhance current capability of the PREQB's ambient monitoring and analysis program.
2.0 METHODS
2.1 Survey design
Sampling locations selected for the 2009 and 2013 surveys used a probabilistic survey
design (USEPA 2004, Olsen and Peck 2008). Twenty-two of the stream sites were
revisits of sites sample in 2009. Site revisits are required in order to detect changes that
may have occurred between the surveys. The probability-based approach allows for
representative sampling of a population of interest and provides an unbiased estimate of
parameters of interest. For example, this survey design is commonly used in estimating
election poll results and key measures of leading economic indicators. For the purposes
of the Puerto Rico streams survey, our goal was to obtain estimates of the stream miles
for selected indicators of biological, water quality, and physical habitat condition. Our
survey design did not use an unequal probability design to account for different Strahler
stream orders. A set of reserve sites was chosen and served as replacements when target
sites were inaccessible due to physical barriers, dry streambeds, or access was denied by
the landowner. Using the National Hydrography Dataset (NHD) it was determined that
approximately 5,000 non-tidal perennial river miles exist in Puerto Rico, and
approximately 71% of the stream miles have a slope of greater than 1% and are
characterized by moderate to steep topography in the watershed. Most of the streams in
Puerto Rico are relatively small and wadeable. It was from this universe of streams that
the probability-based selection of 50 sites was conducted. Since these streams make up
the majority of river miles in Puerto Rico, they were the focus of our initial effort. Future
stream assessments in Puerto Rico should include other important ecological regions like
the karst limestone and coastal plain.
2.2 Study area
All sampling was conducted in February-March 2013 at a total of 50 stream sites located
in the eastern, central, and western mountain drainages of Puerto Rico (Figure 1). The
initial selection of sites is controlled to ensure spatial distribution across Puerto Rico. The
area of study included three geographical regions, humid east central, rainy west central,
and rainy Luquillo Mountains, all characterized by relatively heavy rainfall and steep
topography. The island climate is humid subtropical, with rainfall weakly related to
season and amounts generally greater with tropical disturbances, September through
November. Stream sites and their associated latitude and longitude locations are listed in
Appendix A. Stream size ranged from 1st to 4th order. Stream sites were exclusively high
and moderate in gradient and dominated by riffle-run-pool habitat. The bottom substrate
consisted of boulders (large, medium, small), cobble, and varied amounts of gravel, sand
and silt. 2
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Watershed catchment area upstream of each site had varied land use. Land use was
predominantly forest, pasture, and grassland, with lesser amounts of cultivated cropland
and urbanization. Historically, Puerto Rico land use from the early 1800's to the period
1950, was dominated by subsistence farming, pasture with cattle, and cultivated cropland
(e.g., sugarcane, tobacco, citrus, coffee, and bananas). Since this time, the landscape of
Puerto Rico was significantly altered by deforestation, soil erosion, and sedimentation of
streams and rivers. Agriculture was so prevalent during this period, that by 1950 only 6-
7% of the island remained forested. Today much of the historical agriculture land cover
has been converted to forest and urban land cover.
Figure 1. Map of stream sites in Puerto Rico (green squares indicate sampled in both
2013 and 2009; blue circles indicate sampled in 2013 only; red diamonds indicate
sampled in 2009 only).
2.3 Sample parameters and collection
Sampling was performed through the collective efforts of GLEC and PREQB personnel,
with some guidance provided by EPA Region 2. A total of 50 stream sites was sampled
and revisits were made to five of the sites. Stream sites were assessed using consistent
field methods for biological, water quality, and physical habitat parameters. Biological
condition was assessed using the benthic macroinvertebrate assemblage.
Macroinvertebrates have a long history of use in water quality determinations in
temperate regions of the world and more recently approaches to assess tropical
communities of benthic macroinvertebrates are under development. Macroinvertebrates
have a number of important attributes to the natural structure and function of stream
ecosystems, and therefore are advantageous for assessing water quality. They play an
important role in breaking down coarse organic matter, such as, leaves, woody debris,
and detritus, releasing nutrients and providing a food source for fish and other aquatic
organisms. Macroinvertebrates are good indicators of localized conditions and integrate
the effects of multiple pollutant stressors. Sampling macroinvertebrates is inexpensive
and the identification of organisms is relatively easy with good taxonomic keys and some
training on the taxonomy of aquatic invertebrates.
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At each stream site a single riffle area was chosen closest to the x-site for collection of a
benthic macro in vcrtebrat e sample. Benthic macroinvertebrates were captured from rock
substrate (cobble and small boulder) using a large frame rectangular kick net, constructed
with an 800 x 900 um mesh net (Bode 1991). Sample collection was accomplished by
placing the kick net on the stream bottom, mid-stream in the riffle, while gradually
working the net downstream and laterally (approximately two net widths) for 5 minutes.
The bottom substrate was vigorously disturbed by foot so that sufficient organisms would
be dislodged and swept into the net.
After the sample was collected, large debris were removed from the net, inspected for
organisms, and discarded. Macroinvertebrates and debris retained in the net were placed
in a one liter container and preserved with 10% buffered formalin. Sample containers
were labeled with the appropriate site information and delivered to the EPA Edison
laboratory. Kick nets were thoroughly rinsed and cleaned between stream sites.
The survey supplemented information on biological condition with key measures of
chemical and physical stressors caused by human activities within watersheds. Water
chemistry data were collected to include nutrients, dissolved oxygen, major anions and
cations, turbidity, and suspended solids. Physical habitat data were collected to include
four broad categories of habitat quality, 1) streambed sediments, 2) in-stream fish habitat,
3) riparian vegetative cover, and 4) riparian disturbance. Collectively, these chemical
and physical stressors affect the biological integrity of streams. These major groups of
chemical and physical habitat parameters are consistent with those assessed in the EPA
national stream and river surveys (USEPA 2009), and selected because of regional and
national concerns on the extent to which they are known to impact water and habitat
quality. This does not include all pollutants which may affect water quality and cause
biological impairment, including emerging chemical contaminants and biological
invasive species. Dependent on emerging water quality issues and the availability of
resources, future studies may include an assessment of additional chemical stressors.
Water chemistry and physical habitat data were collected in accordance with the National
Rivers and Streams Assessment: Field Operations Manual (EPA-841 -B-07-009) and the
Quality Assurance Project Plan (EPA-841-B-07-007).
2.4 Setting thresholds
A significant challenge in assessing chemical, physical, and biological condition is
setting expectations for what is natural. Landscapes such as Puerto Rico were highly
altered by subsistence farming and cultivated agriculture from the period 1830 - 1940's,
and post 1950 by industrialization and a rapidly expanding human population. As a
result of this history of anthropogenic disturbance, a least disturbed reference condition
was used to interpret our data. This condition is found in conjunction with the best
physical, chemical and biological habitat given today's state of the landscape. Measures
or criteria for reference condition were selected independently of the macro invertebrate
data as not to bias expectations for biological condition.
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The lack of sufficient chemical and physical data precluded their use to screen levels and
determine whether any stream sites were in a least-disturbed condition. Instead, least
disturbed stream sites were screened by using data collected on watershed land use. In
order for a site to qualify as meeting reference condition, stream watersheds were
required to have a minimum of 85% forest cover since the period of the 1950's until
present. This information was obtained from historical forest maps and using current GIS
land cover data.
This screening approach resulted in a set of least disturbed reference sites that were more
or less evenly distributed east to west across the interior of the island. The distribution of
the sites encompassed most of the natural and human-caused variability known to occur
in regions across Puerto Rico.
Indicator data collected from reference sites were considered representative of a range of
expected values for least-disturbed by human activities and this distribution was used as
the benchmark for setting thresholds. The thresholds indicate distinct condition classes
(e.g., good, fair, poor) and are based on the degree of disturbance drawn from the
reference condition. These thresholds were then applied to the stream survey data and
used to determine the percentage of stream length in each condition category for each
indicator (Appendix B).
Our process of threshold development was similar to the percent range of deviation from
the reference condition, as proposed by EPA's National Rivers and Streams and Lakes
Assessments (USEPA 2006, USEPA 2010, USEPA 2013).
3.0 RESULTS OF THE CONDITION OF PUERTO RICO'S STREAMS
It is the goal of the Clean Water Act, to "restore and maintain the chemical, physical, and
biological integrity of the Nation's waters". To this end, widely accepted aquatic
indicators were used in the assessment of rivers and streams in Puerto Rico. This section
of the report discusses the indicators used (e.g., biological, chemical, physical habitat),
extent of stream miles impaired, and identity and rank of the stressors that potentially
affect biological condition. In estimating the extent of stream miles in good, fair, and
poor condition, confidence intervals are placed on the condition bars for each aquatic
indicator (Figures 2-12). Confidence intervals are simply used to describe the certainty
around values used in estimating condition classes.
In addition, this section of the report discusses the changes in stream condition that have
occurred since the initial survey performed in 2009.
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3,1 Biological indicator
The bent hie macro in vertebrate assemblage was chosen as the biological indicator to
assess the condition of Puerto Rico's streams. Other aquatic communities such as fish
and algae provide important information and are commonly employed by state agencies
to assess biological condition, however, limited resources precluded their use in our
current assessment of Puerto Rico's streams. In addition, indices of biological integrity
used to interpret fish and algae data, have not yet been developed for Puerto Rico
streams.
Macro in vertebrates (shrimp, snails, worms, dragontlies, etc.) are commonly found in
streams located throughout Puerto Rico. The ecology of most aquatic invertebrate taxa
groups is generally understood and can be related to water quality, however, this
knowledge base is more restricted for neotropical streams such as Puerto Rico when
compared to streams in North America. Macroinvertebrates have many advantages for
their use in assessment and water monitoring programs. Direct observation and
assessment of aquatic animals such as macroinvertebrates, provide information on the
integrated effects of stressors (e.g., nutrients, dissolved oxygen, sediment) that occur over
time and space in a watershed.
At each stream site EPA Region 2, PREQB, and Great Lake Environmental Center
(GLEC) biologists collected samples, which were sent to a laboratory to have taxonomic
identifications performed. These data were tabulated and summarized as metrics for
several ecological attributes (e.g., taxa richness, taxa composition, pollution tolerance) of
the macroinvertebrate assemblage. To interpret this data, metrics were aggregated into a
multimetric index of biological integrity used to determine biological condition.
3.2 Development of a multimetric index of biological integrity
The multimetric index of biological integrity (henceforth referred to as the
Macroinvertebrate Integrity Index or Mil) was developed as an indicator of biological
condition. The original index of biological integrity (TBI) was developed for fish
communities found in small Midwestern streams. More recently, numerous IBI's have
been developed for multiple assemblages (e.g., fish, amphibians, macroinvertebrates,
algae) and multiple waterbody resources (streams, non-wadeable rivers, lakes, wetlands,
estuaries), and successfully implemented in state water programs.
One underlying premise for the use of a biological index is that it is capable of detecting
impairment caused by water quality and habitat degradation. The macroinvertebrate
integrity index (Mil) described here was developed using benthic macroinvertebrate data
and calibrated with various environmental data collected over a range of anthropogenic
influences. Individual metrics used to comprise the index are measures of community
structure and function, such as, richness, composition, pollution tolerance, and trophic
feeding measures. Development of the Mil for Puerto Rico streams generally followed
the procedures described in EPA technical guidance (Gibson et al. 1996).
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Steps in this process include a sequential progression listed as follows: 1) select
consistent biosurvey protocols, 2) collect and compile data, 3) stream classification for
regional expectations of reference condition, 4) metric selection and calibration, 5) test of
metrics discrimination ability, and 6) development of the index. Individual metric scores
are combined and averaged to derive a Mil score (0-100). A higher index score is
indicative of better biological condition. Additional information on the development of
the Mil and protocol used to collect benthic macroinvertebrate data can be obtained from
a technical supplement (Kurtenbach 2011).
3.3 Findings for the Mil of biological integrity
For the 2013 Puerto Rico survey a Mil score was calculated for each stream site and
applied to provide estimates of the total stream length in good, fair, and poor condition.
Using a macroinvertebrate indicator of biological condition, 42% (1,219 miles), 34%
(987 miles), and 24% (697 miles) of Puerto Rico's stream length is in good, fair, and
poor condition, respectively (Figure 2). These are compared to the least-disturbed
reference condition established in Puerto Rico. The 42% stream length shown to be in
good condition is considered to be representative of a range of expected values for least-
disturbed reference condition in Puerto Rico.
| 2013 PR Biological Condition
i
¦ Good
Fair
Poor
60
95% confidence
Fair
; Good
10 20 30 40
Percentage of Stream Miles
50
Figure 2. Biological condition of streams based on the Mil (error bars
intervals).
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3.4 Chemical indicators of stress
Chemical stressors are just one of several aquatic indicators of stress. Total phosphorus,
total nitrogen, salinity, and acidification were the chemical stressors considered to be the
most important and pose the greatest threat to aquatic ecosystems and were ultimately
selected for the EPA National Stream Assessments (USEPA 2013, USEPA 2006). Total
phosphorus, total nitrogen, chloride, and dissolved oxygen were considered among a
number of important stressors that are believed to impact stream biota in Puerto Rico, and
were assessed as indicators in the wadeable streams survey. Obviously, the chemical
stressors evaluated here are not exhaustive and other chemical contaminants may affect
biota in Puerto Rico streams, along with other water pollution problems that could
emerge in the future. New aquatic indicators of chemical stressors could be added to
future surveys if adequate resources are available and water program managers request
additional water quality information. Similar to the biological index, thresholds for
interpreting the data were calibrated based on least-disturbed reference condition. See
Appendix B for the threshold concentrations low, medium, and high for TP, TN, and
chloride, and good, fair, and poor for dissolved oxygen.
3.4.1 Phosphorus
Phosphorus is a limiting nutrient for the growth of algae and aquatic plants in aquatic
environments. Limited concentrations of phosphorus serve important physiological
functions in algae and plants for their successful growth and reproduction, and this
primary production provides an important source of food and habitat to higher levels of
aquatic biota (macroinvertebrates, fish, etc.). However, elevated concentrations of
phosphorus in waterbodies can result in excessive plant growth that can harm an aquatic
ecosystem. For example, in streams thick mats of algae may smother rock bottom
substrates that serve as important habitats for aquatic invertebrates and fish, or decay of
excessive plant material may result in the depletion of dissolved oxygen below levels at
which aquatic life cannot survive or reproduce. Aside from the detrimental effects
nutrients can have on aquatic biota, nuisance growth of algae and aquatic plants diminish
the aesthetic appeal of recreational activities such as fishing, swimming and boating.
Sources of nutrients in watersheds are numerous and result from human activities like
farming and lawn care, and can be transferred to streams via stormwater runoff.
Municipal wastewater treatment plant and industrial effluents discharged into streams
provide another major source of nutrients. Moreover, improperly treated sewage, the
result of lags in infrastructure as evidenced by broken pipes and sewage overflows, can
be another important source of nutrients to streams in Puerto Rico.
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Using the total phosphorus indicator, 18% (522 miles), 54% (1,567 miles), and 28% (813
miles) of Puerto Rico's stream length has low, medium, and high concentrations,
respectively (Figure 3).
2013 PR Total Phosphorus Condition
Medium
Low
: 0 10 20 30 40 50 60 70
Percentage of Stream Miles
Figure 3. Total phosphorus concentrations in Puerto Rico streams (error bars = 95%
confidence intervals).
3.4.2 Nitrogen
Nitrogen also, is a limiting nutrient for the growth of algae and aquatic plants, depending
on the local geology. Nitrogen is an important constituent of fertilizers, and similar to
phosphorus, has sources associated with agriculture and residential development,
including wastewater. Nitrogen can also have detrimental effects in excessive amounts,
by stimulating algae and plant growth that may degrade benthic habitat and deplete
dissolved oxygen. Moreover, between nitrogen and phosphorus, the former is often more
limiting in tropical streams and may have greater implications for the ecosystem health of
Puerto Rico streams.
n Low
Medium
« High
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Using the total nitrogen indicator, 18% (522 miles), 62% (1799 miles), and 20% (580
miles) of Puerto Rico's stream length has low, medium, and high concentrations,
respectively (Figure 4).
2013 PR Total Nitrogen Condition
High
Medium
• Low
¦ High
Low
0
10 20 30 40 50 60 70 80
Percentage of Stream Mites
Figure 4. Total nitrogen concentrations in Puerto Rico streams (error bars = 95%
confidence intervals).
3.4.3 Chloride
Chloride is an important anion of many salts. Chlorides are essential elements required
by plants and animals to carry out life functions. However, chloride in elevated
concentrations can have both acute and chronic effects on aquatic life. Salinization of
streams is known to occur with increases in impervious surfaces associated with suburban
and urban development. In drier climates, salinity in streams can occur with agriculture
practices that require significant withdrawals and repeated use of water. Other sources of
chloride include effluent wastewater from industries and sewage treatment plants, and
agricultural runoff.
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Thirty-four percent (987 miles) of Puerto Rico's stream length has low concentrations of
chloride, 56% (1625 miles) has medium concentrations, and 10% (290 miles) has high
concentrations (Figure 5).
High
Medium 56
Low
2013 PR Chloride Condition
Low
Medium
High
20 40 60
Percentage of Stream Miles
80
Figure 5. Chloride concentrations in Puerto Rico streams (error bars = 95% confidence
intervals).
3.4.4 Dissolved Oxygen
A moderate to high level of dissolved oxygen is required by aquatic invertebrates and
fish. In warmwater streams, like those typically found in Puerto Rico, aquatic life may be
put under stress at dissolved oxygen levels below 5.0 mg/1. Most states have water
quality standards set at 5.0 mg/1 to be protective. When excessive organic matter from
such things as animal waste and improperly treated sewage enter a stream, decomposition
of this material by aerobic bacteria can reduce dissolved oxygen concentrations.
Dissolved oxygen levels at 1-2 mg/1 for extended periods of time may result in fish kills.
Dissolved oxygen levels in streams and rivers have improved over the last 40 years from
water quality monitoring conducted in the United States. Flowever, in Puerto Rico,
where improperly treated sewage and overflows due to lags in infrastructure still occur,
there is a greater need for this information.
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A relatively small number of Puerto Rico's stream length is in poor 0% (0 miles)
condition for dissolved oxygen, or fair 8% (232 miles), while 92% (2670 miles) is in
good condition (Figure 6).
2013 PR Dissolved Oxygen Condition
Poor 0
• Good
Fjir
¦ Poor
0 20 40 60 80 100 120
Percentage of Stream Miles
Figure 6. Dissolved oxygen conditions in Puerto Rico streams (error bars = 95%
confidence intervals).
3.5 Physical habitat indicators of stress
Human activities such as agriculture, construction (e.g., road, housing, commercial), and
mining may cause erosion of sediment. Puerto Rico has become increasingly urbanized
with associated construction that results in the removal of riparian vegetation and erosion
of soil. Another common activity is sand and gravel mining in streams and adjacent
corridors that have resulted in the destruction of in-stream habitat and removal of riparian
vegetation.
Upon entering a stream by stormwater runoff, sediment may be harmful to aquatic
invertebrates and fish by covering the stream bottom and excluding them from important
habitat. Alteration of riparian vegetation along a stream corridor can increase the
transport of sediment, nutrients, and other pollutants resulting in harmful effects to water
quality and aquatic habitats. In addition, riparian vegetation provides shade and therefore
constant stream water temperature. Fallen trees provide important instream habitats and
woody debris (twigs and leaves) provide important organic matter with nutrients that fuel
healthy stream ecosystems. Cumulative effects of human activities impact the physical
habitat of streams, and can ultimately affect the biota living on them.
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Similar to the water chemistry indicators, there are numerous physical habitat indicators
of stress. The National Wadeable Streams Assessment (USEPA 2006) selected four
physical habitat stressors as indicators: streambed sediments, in-stream fish cover,
riparian vegetation, and riparian disturbance. For purposes of consistency with the
national survey, the same four broad categories of physical habitat indicators were used
in the Puerto Rico streams survey. In Puerto Rico, little information exists to report the
potential impacts of physical habitat alteration on streams and linking them as a cause of
impairment.
See appendix B for the threshold ranges low, medium, and high for % sand, %
embeddedness, and riparian disturbance, and good, fair, and poor for riparian vegetation
and fish cover.
3.5.1 Streambed Sediments (percent sand and percent embeddedness)
Streambed sediments were assessed making observations of the percent of sand covering
an area of bottom substrate and the relative depth that bottom substrate such as cobble
and boulders was filled with fine sediment. Impacts of fine sediments result from human
activities on the landscape, like agriculture, construction, grazing, and mining. Important
aquatic habitat is lost when space between rock substrates become filled with sediment.
These spaces provide important cover and feeding areas for aquatic invertebrates and
fish, including important habitat for successful hatching of eggs and development of
young.
13
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Twenty-two percent (638 miles) of the stream length in Puerto Rico has excessive or high
levels of sand based on the distribution of least-disturbed reference condition (Figure 7).
The remainder of stream length, 48% (1393 miles) and 30% (871 miles) had medium to
low levels of sand. The other indicator of excessive fine sediment, percent
embeddedness, occurred in highest amounts for 18% (522 miles) of the stream length of
Puerto Rico (Figure 8). Embeddedness condition for 18% (522 miles) and 64% (1,857
miles) of the assessed stream length was medium and low, respectively. Similar with
percent sand, condition categories for percent embeddedness are based on least-disturbed
reference condition.
2013 PR % Sand Condition
¦ Low
Medium
¦ High
0 10 20 .30 40 50 60 70
Percentage of Stream Miles
Medium
Figure 7. Sediment (percent sand) levels in Puerto Rico streams (error bars = 95%
confidence intervals).
2013 PR % Embeddedness Condition
High
Medium 18
Low
I Low
Medium
i High
0 10 20 30 40 SO 60 70
Percentage of Stream Miles
SO
Figure 8. Sediment (percent embeddedness) levels in Puerto Rico streams (error bars
95% confidence intervals).
14
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3.5.2 Riparian Vegetative Cover
Riparian vegetative cover is essential for a healthy stream ecosystem. Good vegetative
cover stabilizes stream banks, preventing erosion of sediment and impacts of nutrient
runoff. Shading provided by the riparian canopy helps to maintain constant stream
temperature. Equally important, leaf and woody material from riparian vegetation
provides an important source of food and cover to aquatic organisms. The condition and
extent of riparian vegetation was assessed by estimating the amount of overhead canopy,
understory cover, and layer of ground cover. The estimated aerial coverage provided by
these three layers is summed and compared to the range expected, based on the least-
disturbed reference condition.
Condition of the riparian vegetation was assessed as poor, fair, and good for 50% (1451
miles), 22% (638 miles), and 28% (813 miles) of the stream length in Puerto Rico (Figure
9).
2013 PR Riparian Vegetative Condition
0 10 20 30 40 50 60 70
Percentage of Stream Miles
Figure 9. Riparian vegetative cover in Puerto Rico streams (error bars = 95% confidence
intervals).
3.5.3 Fish Habitat Condition
Altho ugh fish were not assessed in this survey of Puerto Rico streams, important features
of fish habitat were measured. These included cover and concealment features such as
undercut banks, boulders, large woody debris, and overhanging vegetation. Streams with
a greater diversity of these cover types have more complex habitat and generally a more
diverse community of macro invertebrates and fish.
15
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Using the fish cover indicator, 50% (1451 miles), 30% (871 miles), and 20% (580 miles)
of Puerto Rico's stream length is in poor, fair, and good condition, respectively (Figure
10).
2013 PR Fish Habitat Condition
Poor
Fair
¦ Good
¦ Poor
Good
0
10
20
30
40
50
60
70
Percentage of Stream Miles
Figure 10. In-stream fish habitat in Puerto Rico streams (error bars = 95% confidence
intervals).
3.5.4 Riparian Disturbance
As human activities increase in a watershed they often occupy or encroach upon the
riparian stream corridor. Riparian disturbance in the Puerto Rico streams survey was a
measure of human disturbance and specific activities that occur along the stream reach.
These measures were taken from riparian plots, spaced evenly at transects laid along the
stream study reach. Levels of riparian disturbance increase as the number of human
activities (buildings, roads, trash, row crops, grazing, etc.) recorded in the riparian plots
increase. For example, if less than one-third of the riparian plots had human influence,
then the stream reach was assessed low disturbance.
16
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Twenty percent (580 miles) of the Puerto Rico stream length has high levels of human
influence in the adjacent stream riparian corridor (Figure 11). Thirty-eight percent (1,103
miles) and 42% (1,219 miles) of the Puerto Rico stream length has medium and low
levels of human activity in the riparian zone.
2013 PR Riparian Disturbance
Medium
Low
: Low
Medium
i High
0 10 20 30 40 50 60
Percentage of Stream Miles
Figure 11. Riparian disturbance in Puerto Rico streams (error bars = 95% confidence
intervals).
3.6 Ranking of stressors
Before management decisions can be made on the importance of various chemical and
physical habitat stressors examined for the Puerto Rico streams survey, a comparison of
the extent of each stressor is required. Figure 12 illustrates a comparison of the extent of
stressors as the proportion of stream length ranked in poorest category for each stressor.
Each stressor is ordered (top to bottom) from the greatest to least stream length in the
poorest category. It should be noted that stressors with the highest stream length in poor
condition do not necessarily determine the influence it has on biological condition. The
relative severity that each stressor has on biological condition requires an analysis of
relative risk, which was not performed in the current survey due to a small sample size.
Future streams assessment in Puerto Rico should be conducted to estimate the severity of
different stressors on macroinvertebrate communities.
17
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The most common stressors for stream length in Puerto Rico are the loss of complexity of
the riparian vegetation and poor fish habitat. Fifty percent of the stream length (1,451
miles) was determined to be poor for these indicators of physical habitat. The stressors
ranking poor for intermediate length of streams in Puerto Rico, included nutrients (TN
and TP), and habitat indicators of sedimentation and riparian disturbance. The least
common stressors of the stream length in poor condition in Puerto Rico, were chloride
10% (290 miles) and dissolved oxygen 0% (0 miles).
2013 PR Streams Stressor Extent
Riparian Vegetative Cover
Fish Cover P
Total Phosphorus V£
%Sand
Total Nitrogen
Riparian Disturbance Hi]
% Embeddedness
Chloride ¦—
Dissolved Oxygen
o
0 10
20 30 40 50 60
Percentage of Stream Miles
70
¦ Dissolved Oxygen
Chloride
¦ % Embeddedness
¦ Riparian Disturbance
Total Nitrogen
" % Sand
¦ Total Phosphorus
¦ Fish Cover
a Riparian Vegetative Cove
Figure 12. Extent of stressors as proportion of stream length ranked in poorest category
for each stressor (error bars = 95% confidence intervals).
Changes in stream condition-
One important goal of the probabilistic stream surveys in Puerto Rico is to detect change
between two points in time, and ultimately discern trends over time in measures of
biological condition and key aquatic indicators of water quality and physical habitat.
Policy makers need this information to determine if water management policies are
working, if not, tweaking and adjusting water programs to address the right pollution
problems and achieve environmental results. Because the current survey is the second of
two surveys, results are reported as a change of two points in time and not the assessment
of trends. A statistical method for estimating changes between the 2009 and 2013
surveys was applied. 18
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Results for Mil scores, chemical stressors, and physical habitat scores are illustrated in
figures 13 and 14. No statistically significant change in the percentage of good Mil
scores was noted between the reporting periods 2009 and 2013. A statistically significant
decrease of stream miles in good condition for phosphorus was detected in the 2013
survey. Between 2009 and 2013 this difference was 12%. For two of the habitat
indicators, between the period 2009 and 2013, riparian vegetative cover and percent
embeddedness both had a statistically significant increase of stream miles in good
condition. Stream miles in good condition increased by 22% and 26%, respectively.
2009 vs 2013 PR Biology in Good Condition
| 2009
MMI Score
2013 '
0 10 20 30 40 50 60
Percentage of Stream Miles
Figure 13. Change in macro invertebrate condition based on percent of stream length in
good condition.
19
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2009 vs 2013 PR Stream Stressors in Good Condition
iparian Vegetative Cover
Total Phosphorus
Total Nitrogen
Fish Cover
% Sand
% Embeddedness
Chloride
Riparian Disturbance
Dissolved Oxygen
0 20 40 60 80 100 120
Percentage of Stream Miles
Figure 14. Change in stream chemical and habitat indicators, based on percent of stream
length in good condition (stars indicate statistically significant change).
4.0 DISCUSSION AND MANAGEMENT IMPLICATIONS OF FINDINGS
4.1 Summary
Puerto Rico is a small island in a chain of Caribbean islands. Although small in stature
compared to other world land masses, Puerto Rico has diverse freshwater aquatic
resources and aquatic communities that live in them. Excluding tidal waters, there are
approximately 5,000 miles of perennial streams with drainage networks across the island.
Puerto Rico with its abundance of streams has a great need for monitoring surveys that
provide accurate information on current environmental conditions.
20
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The 2013 survey of Puerto Rico streams was the second ever use of a probabilistic
statistical design to obtain a statistically valid estimate of environmental conditions. The
survey provided additional information and another snapshot of the current condition of
Puerto Rico streams. The survey was able to achieve three desired objectives: (1)
determine the percent of the streams in Puerto Rico in good, fair, and poor condition for
key indicators of ecological health and human influence, (2) identify and rank what is the
relative importance of key chemical and physical habitat stressors, and (3) determine
what are the changes in stream condition since the 2009 survey. Future stream surveys
with a similar statistical design may be used to detect trends of environmental conditions
and judge the effectiveness of water resource policies and decision making.
Using a macroinvertebrate indicator of biological condition, 24% of the Puerto Rico
stream length was determined to be in poor condition. This is approximately half the
percent of stream miles in poor condition reported for the United States (USEPA 2006)
and Puerto Rico in 2009.
Results of the survey also show the current extent of stressors across Puerto Rico. The
most common stressors for stream length in Puerto Rico are the loss in complexity of the
riparian vegetation and impaired fish habitat. Fifty percent of the stream length (1,451
miles) was determined to be poor for these indicators of physical habitat. Stressors
ranking poor for intermediate length of streams in Puerto Rico, included nutrients (TN
and TP), and habitat indicators of riparian disturbance and stream sediment. The least
common stressors of the stream length in poor condition in Puerto Rico, were chloride
10% (290 miles) and dissolved oxygen 0%.
As previously stated, an important goal of the Puerto Rico streams survey was to
determine the importance and extent of chemical and physical habitat stressors. Ranking
the stressors by proportion of stream length in the poorest category, riparian vegetative
and fish cover (50%) and dissolved oxygen (0%), have the greatest and least importance.
Other stressors ranked to the proportion of the stream length in poor condition included,
total phosphorus (28%), percent sand (22%), total nitrogen (20%), riparian disturbance
(20%), percent embeddedness (18%), and chloride (10%).
One other important goal of the current Puerto Rico streams survey was to discern any
significant change in stream conditions since 2009 and ultimately examine trends over
time as additional surveys are conducted. Three of the aquatic indicators showed a
statistically significant change. Riparian vegetative cover and percent embeddedness had
an increase of stream length in good condition. In contrast, total phosphorus had a
decrease of stream length in good condition.
At this time, changes over the period 2009-2013 cannot be tied to specific human
activities and could in fact be associated with the natural variability of stream systems.
More likely it is some combination of these factors. As trends emerge over future
surveys and additional information becomes available, we likely will be able to better
explain the causes of change in our aquatic indicators.
21
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4.2 Future direction
One of the most important objectives of the Puerto Rico streams survey was to establish a
baseline of biological condition using a benthic macro invertebrate indicator. Of equal
consequence, a rich data set was compiled of water chemistry and physical habitat
components. Collectively, these data can be used to inform decision-makers, compare
results with previous surveys, establish associations with biological condition for the
development of aquatic life criteria, and guide best management practices.
A compilation of findings from state water monitoring programs as reported in 305(b)
reports and results of the EPA Wadeable Streams Assessment (USEPA 2006) have
identified nutrients and sediments as a leading cause of water quality impairment. In
addition, the percentage of stream length rated poor for riparian disturbance was
comparable to nutrients and strearnbed sediments in the national survey. Findings of the
Puerto Rico streams survey are fairly consistent with the USA national-scale assessments
for nutrient, sediment, and riparian condition. An outcome of these findings has been the
drafting of guidance by EPA for the development of regional nutrient criteria (USEPA
1998) and a commitment by federal and state agencies to develop sediment criteria
(Bryce et al. 2010, Cantilli et al. 2006). State and region-scale studies are currently being
conducted to develop biologically based criteria for nutrients (TP and TN) and sediments,
with the goal of establishing water quality values that are protective of aquatic life.
However, thresholds established for temperate North American streams may not apply to ,
the protection of aquatic organisms in streams of Puerto Rieo. Data collected from the
2009 and 2013 Puerto Rico stream surveys in conjunction with recent surveys of
reference streams should provide the initial datasets needed to refine and develop
numeric water quality criteria for the protection of aquatic life.
In addition, data collected from the 2009 and 2013 Puerto Rico stream surveys can be
used in conjunction with water quality data acquired by the Puerto Rico Environmental
Quality Board (EQB) to assist them in their water resource decision-making and
fulfillment of requirements to report to EPA on the current status of water quality in the
different water resources throughout Puerto Rico. More specific use of the data for the
long term include, evaluation of the effectiveness of restoration activities used to control
non-point source pollution and support for the development of water quality standards.
22
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The 2009 and 2013 surveys provide a solid baseline, but only give a snapshot of current
stream conditions. Future probabilistic design stream surveys in Puerto Rico should
continue in order to assess changes and detect trends in stream condition over time. To
detect future trends, subsequent surveys will require a balance of revisited and new sites.
Both surveys in 2009 and 2013 used a probability-based sampling design with an equal
probability of selection by Strahler order, meaning that sites on small or large streams
could be selected, but likely smaller streams were selected because they are more
numerous. Future surveys could accommodate an unequal probability design if the
objective is to obtain an equal number of sites by stream-order category (1st, 2nd, 3rd+).
Other considerations for future surveys include how to deal with physical inaccessibility
of sites and ensuring that sites classified as flowing-water are not nonperennial. Of the
2013 sites visited, 9 were found dry, 7 determined to be inaccessible, and 1 was a lake.
These stations were not sampled and required the use of over-sample sites. Future
improvements in the National Hydrography Database and EPA's River Reach File should
reduce some nonperennial streams misclassified as flowing-water. It should also be
noted there is annual variation in stream flows. Three stream sites sampled in 2009 and
revisited again in 2013 were dry.
The 2009 and 2013 surveys of Puerto Rico streams included only one biological indicator
(benthic macroinvertebrates). Beginning with the 2009 streams survey, an approach using
macro invertebrates to assess environmental degradation was not fully developed for
Puerto Rico streams. In contrast to temperate North America, where bioassessment
techniques have been developed and successfully implemented to measure environmental
conditions, a similar level of development is lacking on island streams throughout the
Caribbean. Other important aquatic assemblages (fish and algae) could be incorporated
into future surveys once biological survey techniques are tested and assessment
approaches are developed for use on Puerto Rico streams. This is an important
consideration because aquatic assemblages (macroinvertebrate, fish, and algae) are
known to respond to stressors differently. Aquatic indicators of stress (chemical and
physical habitat) selected for the initial Puerto Rico streams assessment were fairly
consistent with ones selected for EPA's National Wadeable Streams Assessment (USEPA
2006). Limited resources placed constraints on the number of indicators of aquatic
stressors that could be implemented. However, this does not preclude the importance of
having good information on chemical contaminants in sediment and aquatic biota, or
diminish the need to address emerging stressors of concern.
23
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Further efforts are also needed to determine reference condition for additional sites with
minimum human disturbance. Thresholds established for reporting good, fair, and poor
stream condition for the 2009 and 2013 assessment of Puerto Rico streams were based on
least-disturbed reference sites distributed across the island. Most of these sites were
selected from independent stream studies and screened using criteria based on historical
forested land-use. To be effective, reference conditions should apply to individual stream
segments and similar waterbodies across geographic regions. Regional changes in the
distribution and species composition of aquatic fauna are known to occur with differences
in climate, geology, hydrology, biogeography, and landscape. At present, no ecoregion
or similar regional approaches have been developed for Puerto Rico. Future assessments
of Puerto Rico streams may require some refinement of thresholds if significant natural
regional patterns are demonstrated to occur.
To build on the findings and successful implementation of the 2009 and 2013 Puerto Rico
stream surveys, discussions should begin on the next assessment period, trends
assessment, future stakeholder needs, future people and funding resources, and new
indicators research to fill information gaps. Maintenance of a five year reporting cycle as
is currently being employed by EPA's National Aquatic Resources Assessments, would
require the next assessment of Puerto Rico streams be performed in 2018. Objectives of
this survey will be to determine trends in stream condit ion since 2009 and 2013, establish
additional baseline information, and implementation of additional indicators. The extent
to which these objectives can be achieved will depend on the collaborative input and
needs identified by stakeholders, including sufficient personnel and funding to implement
the survey. Additional research is essential to enhance the scientific rigor of stream
assessments conducted in Puerto Rico. Unlike temperate North America, few studies on
Caribbean streams have demonstrated regional-scale relationships between biological
condition and severity of chemical and physical habitat stressors.
24
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Literature Cited
Bode, R.W., M.A. Novak, and L.E. Able. 1991. Methods for rapid bioassessment of
streams. New York State Department of Environmental Conservation, Division of
Water, Albany, NY.
Bryce, S.A., G.A. Lomnicky, and P.R. Kaufmann. 2010. Protecting sediment-sensitive
aquatic species in mountain streams through the application of biologically based
streambed sediment criteria. Journal of the North American Bentho logical Society
29:657-672.
Cantilli, R., R. Stevens, W. Swietlik, W. Berry, P. Kaufmann, J. Paul, R. Spehar, S.
Cormier, and D. Norton. 2006. Framework for developing suspended and bedded-
sediments (SABS) water quality criteria. EPA822-R-06-001. U.S. Environmental
Protection Agency, Washington, DC.
Gibson, G.A., M.T. Barbour, J.B. Stribling, J. Gerritsen, and J.R. Karr. 1996. Biological
criteria: Technical guidance for streams and rivers. EPA/822-B-96-001. U.S.
Environmental Protection Agency, Office of Science and Technology, Washigton, DC.
Hunter, J.M. and S.I. Arbona. 1995. Paradise lost: an introduction to the geography of
water pollution in Puerto Rico. Social Science and Medicine 40(10):1331-1355.
Kurtenbach, J.K. 2011. Macro invertebrate protocol and development of the Puerto Rico
high gradient streams benthic index. U.S. Environmental Protection Agency, Region 2,
Edison, NJ.
Olsen, A.R. and D.V. Peck. 2008. Survey design and extent estimates for the Wadeable
Streams Assessment. Journal of the North American Bentho logical Society 27:822-836.
U.S. Environmental Protection Agency. 1998. National strategy for the development of
regional nutrient criteria. EPA822-R-98-002. U.S. Environmental Protection Agency,
Washington, DC.
U.S. Environmental Protection Agency. 2004. Wadeable streams assessment: quality
assurance project plan. EPA841-B-04-005. U.S. Environmental Protection Agency,
Washington, DC.
U.S. Environmental Protection Agency. 2006. Wadeable streams assessment: a
collaborative survey of the nation's streams. EPA 841/B-06/002. U.S. Environmental
Protection Agency, Washington, DC.
U.S. Environmental Protection Agency. 2007. National rivers and streams assessment:
quality assurance project plan. EPA841-B-07-007. U.S. Environmental Protection
Agency, Washington, DC.
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U.S. Environmental Protection Agency. 2009. National rivers and streams assessment:
field operations manual. EPA-841-B-07-009. U.S. Environmental Protection Agency,
Washington, DC.
U.S. Environmental Protection Agency. 2010. National lakes assessment: a
collaborative survey of the nation's lakes. EPA 841-R-09-001. U.S. Environmental
Protection Agency, Washington, DC.
U.S. Environmental Protection Agency. 2011. National rivers and streams assessment:
fact sheet. EPA941-F-11-001. U.S. Environmental Protection Agency, Washington, DC.
U.S. Environmental Protection Agency. 2013. National rivers and streams assessment
2008-2009: a collaborative survey. EPA/841/D-13/001. U.S. Environmental Protection
Agency, Washington, DC.
U.S. General Accounting Office. 2000. Water quality: key EPA and State decisions
limited by inconsistent and incomplete data. GAO/RCF.D-OO-54. U.S. Government
Accountability Office, Washington, DC.
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Stream site identifications with associated latitudes and longitudes
(in decimal degrees)
SiteJD
Collection Date
Lat_DD
LonJDD
PR13001
3/1/2013
18.35705
-66.42322
PR13002
2/27/2013
18.14683
-65.93788
PR13003
3/6/2013
18.20471
-66.36970
PR13005
3/11/2013
18.26359
-66.13059
PR13006
3/6/2013
18,07240
-66.03949
PR13007
3/11/2013
18.08405
-65.90372
PR13010
3/9/2013
18.16725
-66.13052
PR13011
2/27/2013
18.31253
-67.11500
PR13012
3/12/2013
18.19552
-66.62402
PR13013
3/1/2013
18.28418
-65.73920
PR13014
3/4/2013
18.29325
-66.42633
PR13015
2/28/2013
18.22910
-66.83912
PR13016
3/8/2013
18.05339
-66.81495
PR13017
3/1/2013
18.34543
-66.40602
PR13018
3/2/2013
18.15838
-65.91971
PR13020
3/7/2013
18.25550
-66.71927
PR13021
3/6/2013
18.30581
-66.20266
PR13022
3/6/2013
18.02936
-66.16324
PR13023
3/11/2013
18.08969
-65.94844
PR13024
3/12/2013
18.28211
-66.55520
PR13025
3/11/2013
18.27816
-65.99055
PR13028
3/5/2013
18.12750
-66.63653
PR13059
2/28/2013
18.29310
-66.87664
PR13061
3/9/2013
18.22478
-65.92201
PR13062
2/28/2013
18.23835
-66.31340
PR13063
3/4/2013
18.33282
-67.00369
PR13064
3/8/2013
18.12917
-66.86404
PR13070
2/27/2013
18.35605
-67.11742
PR13072
3/9/2013
18.10699
-66.98674
PR13073
3/2/2013
18.15334
-65.87349
PR13074
3/7/2013
18.17864
-66.73610
PR13076
2/27/2013
18.10872
-65.99136
PR13077
3/8/2013
18.12977
-66.45368
PR13078
3/5/2013
18.14040
-66.63754
PR13079
3/1/2013
18.36515
-65.78280
PR13080
3/4/2013
18.28257
-66.38200
PR13081
3/4/2013
18.31138
-66.95674
PR13082
3/9/2013
18.21331
-67.05843
PR13083
2/28/2013
18.25839
-66.25293
PR13084
3/5/2013
18.10715
-66.28689
PR13085
3/5/2013
18.15200
-66.18277
PR13086
3/7/2013
18.29128
-66.67245
PR13087
3/13/2013
18,35354
-65.87223
PR13088
3/8/2013
18.12473
-66.49588
PR13089
3/2/2013
18.21141
-66.91873
PR13090
3/2/2013
17.99086
-66.61973
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Stream site identifications with associated latitudes and longitudes
Appendix A
(in decimal degrees)
Site J D Collection Date LatJDD Lon_DD
PR13092 3/13/2013 18.24973 -66.92707
PR13093 3/7/2013 18.15735 -66.04000
PR13094 3/12/2013 18.13473 -66.70718
PR13097 3/14/2013 18.27846 -65.89342
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Appendix B: Thresholds for Biological, Chemical and Physical Habitat Indicators
Biological Condition (Mil score)
G - >53
F - 44-53
P - <44
Total Phosphorus (ppm)
L - <0.036
M - 0.036-0,080
H - >0.080
Total Nitrogen (ppm)
L - <0.25
M - 0.25-1.19
H - >1.19
Chloride (ppm)
L - <11
M- 11-28
H - >28
Dissolved Oxygen (ppm)
G - >5
F - 3-5
P - <3
Percent Sand
L - <8
M - 8-35
H - >35
Percent Embeddedness
L - <41
M-41-61
H - >61
% XCMG (Riparian Vegetation)
G - >201
F - 151-201
P - <151
%XFCALL (Fish Cover)
G - >40
F- 25-40
P -<25
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Riparian Disturbance (number of plots)
L- 0-3
M - 4-9
H- 10
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