university of rhode island linda t green...

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University of Rhode Island

Cooperative Extension

URI Watershed Watch Natural Resources Science Dept.

The Coastal Institute in Kingston

1 Greenhouse Road

Kingston, RI 02881

Linda T Green, Program Director

401-874-2905 - [email protected]

Elizabeth M. Herron, Program Coordinator

401-874-4552 - [email protected]

www.uri.edu/ce/wq/ww/

URI Watershed Watch Program

Bristol Harbor Monitoring Results 2009 - 2012 April 2013

Elizabeth Herron and Linda Green, URI Watershed Watch

Water Quality Summary: An additional year of monitoring combined with additional upstream

sites and unique weather and other events continues to strengthen our understanding of

conditions in Bristol Harbor. As concluded previously, both the on-site monitoring and laboratory

analyses indicate that with the exception of the Silver Creek outlet (#3), Bristol Harbor itself is in

generally good condition. Nutrients were low to moderate, although in some cases quite variable

between years. Dissolved oxygen levels were usually sufficient for most aquatic species, although

recently (2011 and 2012) there were periods of low dissolved oxygen at a number of sites, which

creates potentially stressful conditions for species such as clams. Chlorophyll concentrations, an

indicator of algal productivity algae levels, were generally in the low to moderate range, but

brief algal blooms were noted at a number of sites. Bacteria levels were often within both

acceptable shellfishing and swimming criteria, but were generally higher in 2011 and 2012 than

previous years.

Save Bristol Harbor (SBH) continues to use the data generated through this monitoring effort to

explore the watershed by adding additional upstream monitoring sites (#14 DaPonte Pond

/Wood St. and #15 Silver Creek at Gooding Ave.) in order to identify sources of contamination.

This followed the organization taking action on the 2009 results which identified Silver Creek as a

source of excess nitrogen and bacteria, impacting nearby dissolved oxygen levels. Monitoring at

the upstream sites added in the 2010 season combined with these newer sites is strengthening

the indications that the sources are upstream of where Silver Creek enters the harbor, but has not

haven’t quite “nailed it down” yet.

The dynamic nature of the harbor ensures that there will be fluctuations in water quality

conditions from year to year. The commitment of Save Bristol Harbor to comprehensive long-term

data collection in order to establish and confirm baseline conditions and track trends is

commendable and vital for protecting this essential resource. Ideally, a full ten years of data are

typically needed to develop good baseline data. During that time other hot spots may emerge,

and most normal annual weather cycles will have been encountered. Continued expanded

monitoring in the Silver Creek watershed to better bracket current problem areas is critical to

identify sources and to affect solutions. Unfortunately, visible water quality results of watershed

remediation efforts often lag behind the actual work, so there is a lot of work ahead for the

members of this dedicated organization and its partners.

University of Rhode Island, United States Department of Agriculture, and local

governments cooperating. Cooperative Extension in Rhode Island provides equal

opportunities without regard to race, age, color, national origin, sex or sexual

preference, creed, or handicap.

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Introduction: For the fourth year volunteers coordinated by Save Bristol Harbor monitored

water quality monitoring in the Bristol Harbor watershed in 2012. Save Bristol Harbor’s Predictive

Habitat Model Committee began the water quality data collection phase of the model

development process in cooperation with the University of Rhode Island (URI) Watershed Watch

program in the spring of 2009. The committee, comprised of scientists from Roger Williams and

Brown Universities, SBH volunteers, as well as students from Mt. Hope High School and Roger

Williams University, initially identified eight (8) monitoring sites around the perimeter of Bristol

Harbor for monitoring in 2009. Dock and shoreline sites allowed easy and safe access for

volunteers, and good distribution around the harbor (see Table and Figure 1 for site information).

As a result of finding high nitrogen and bacteria at #3 Silver Creek outlet, in 2010 three upstream

sites were added, as well as an additional shoreline site closer to Narragansett Bay (#12

Herreshoff Dock). For 2011 that outer site was switched to Mack’s Dock (#13) in an effort to

improve access, but that part of the harbor proved to be strongly influenced by localized

conditions, so the Herreshoff Dock site was reinstated as the site nearest the Narragansett Bay in

2012. Also added in 2012 were upstream sites (#14 and #15) designed to help better target

potential contamination sources.

Figure 1. Bristol Harbor Monitoring Sites

Table 1: Bristol Harbor Water Quality Monitoring Site Information (2009 – 2012 sites)

Site ID Site Description Site ID Site Description Site ID Site Description

BH 1 Elks Club Dock BH 6 Sanroma BH 11 Silver West Branch

BH 2 BH Inn Dock BH 7 BH Yacht Club Dock BH 12 Herreshoff Dock

BH 3 Silver Creek Outlet BH 8 Brito Dock BH 13 Mack’s Dock

BH 4 Windmill Point Dock BH 9 Silver Bridge BH 14 DaPonte P/Wood St

BH 5 Mill Pond BH 10 Silver East Branch BH 15 Silver @ Gooding .

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Volunteer Monitoring: SBH volunteers were trained by URI Watershed Watch (URIWW) staff to

conduct their water quality monitoring. The water quality monitors were provided with monitoring

equipment and supplies as well as a written monitoring manual that detailed all the procedures.

Monitoring followed a schedule designed to cover the period of peak biological activity in the

harbor - from mid-May through mid-October. The schedule consisted of biweekly early morning

on-site monitoring of water temperature, salinity, dissolved oxygen content and chlorophyll

sample collection and processing. (Please see URIWW monitoring manuals and field quality

assurance project plans available on the website at www.uri.edu/ce/wq/ww/Manuals.htm for

more specific information.) All on-site monitoring data was submitted to URIWW on monitoring

postcards or online.

In addition to the bi-weekly on-site monitoring, once a month the volunteers also collected a

suite of water samples, which were brought to a central collection point in Bristol. From there the

samples were packed on ice in a cooler and brought to the URIWW Analytical Laboratory in the

College of the Environment and Life Sciences in Kingston. These samples were analyzed for

bacteria, pH, nitrogen, phosphorus, and chlorophyll according to standard URIWW laboratory

procedures (see Quality Assurance Project Plan: University of Rhode Island Watershed Watch

Analytical Laboratory www.uri.edu/ce/wq/wq/ww/Qapps.htm for additional information). The

sample schedule was designed to ensure that samples were collected early in the morning in

order to monitor the lowest daily dissolved oxygen, and that the samples would reach the URIWW

laboratory within acceptable hold times. Brief descriptions of key parameters monitored, the

criteria used to assess conditions, data summaries, including charts and discussions of the results,

follow. Parameters not discussed can be found in Appendix A.

Weather summary: Weather can significantly affect water quality, often confounding the

assessment of water quality trends. This summary is based on weather data from the URI Weather

Station in Kingston, RI, which may not exactly represent conditions in Bristol, but provides a good

overview. Departures from normal were in relation to the average temperature and precipitation

values over the past thirty (30) years. While temperatures in 2009 were somewhat variable,

starting in 2010, every month (except January 2011, and November 2012) above normal temperature, with annual averages more than 2 ° F above normal. Warmer air temperatures

Figure 2. Weather Summary Charts

4.94.2

1.72.9

-0.1

2.53.4

0.5

3.3

-3.4

4.1

-4

-2

0

2

4

6

2009 2010

2011 2012

2009 - 2012 TEMPERATURE DEPARTURE FROM NORMAL

De

gre

es

F

-0.38

-2.35-1.62

1.140.20 0.64

1.53

-1.25 -1.58

2.93

-3.0

-1.0

1.0

3.0

5.0

7.0

9.0

2009 2010

2011 2012

2009 - 2012 PRECIPITATION DEPARTURE FROM NORMAL

Inc

he

s

14.5

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can result in warmer water temperatures, increased biological activity, lower dissolved oxygen

levels and changes in precipitation (figure 2).

In 2009 record breaking July precipitation contributed to nearly 8” above normal annual rainfall.

Rainfall in 2010 also set records. The 2010 March floods were due to the nearly 20” of rain (as

recorded in Kingston) contributing to an annual value of 8+” above normal rainfall. However,

without that rain, annual precipitation would have been more than 6” below normal since the

summer and fall of 2010 was quite dry. In contrast, August through October was quite rainy in

2011, resulting in precipitation that was 7.5” above normal for the year. Rainfall was decidedly

lower in 2012, with precipitation below average six months out of twelve. Super Storm Sandy

occurred after the completion of the monitoring season (figure 2).

Bristol Harbor field monitoring descriptions and summaries: Volunteers measured a number

of key water quality indicators using field kits and instruments. These field measurements included

temperature, dissolved oxygen (DO), salinity and also processing of samples for subsequent

URIWW laboratory analysis of chlorophyll. Water samples were taken from a depth of half a meter

(0.5m) from the surface or midway to the bottom using either a sampling pole or the “one arm

sampler” – the volunteer’s arm that is. With the exception of temperature, duplicate samples

were collected, and then duplicate measurements were made for each of the parameters, with

the average reported in Figures 3a and 3b.

Dissolved oxygen and water temperature data tell us quite a bit about the health of the harbor.

Oxygen is critical to the survival of most of the animals and plants that live in the water; generally

the more oxygen, the healthier the ecosystem. Dissolved oxygen levels below 5 milligrams of

oxygen per liter of water (mg/L) can be stressful to many forms of life, particularly at the juvenile

life stage. Dissolved oxygen levels below 2 mg/L, also known as hypoxic or low oxygen, are lethal

for many species. When DO concentrations fall below 0.5 mg/L, the water is called anoxic, and

plants or animals that require oxygen can’t survive in that area. Oxygen enters the water through

two natural processes: (1) diffusion from the atmosphere and (2) photosynthesis by aquatic

plants, including algae. The mixing of surface waters by wind and waves increases the rate at

which oxygen from the air can be dissolved or absorbed into the water.

Temperature and salinity dictate the maximum DO that can be dissolved into salt water. As the

temperature increases, the amount of oxygen that can be dissolved into the water decreases.

For example, salt water at 5°C can contain up to 10.5 mg/L, but at 25°C it can only hold 7.0

mg/L. Higher salinity and suspended solids levels also reduce the amount of oxygen that can be

dissolved into the water.

Dissolved oxygen is used by aquatic animals, as well as by plants at night when there isn’t any

sunlight for photosynthesis. Thus DO levels are typically lowest early in the morning before

photosynthesis associated with the rising sun has driven up DO levels, which is why SBH volunteers

monitored around 6:00 am. Bacteria, fungi, and other decomposer organisms also reduce DO

levels by consuming oxygen while breaking down organic matter, such as dead algae. Algae

blooms can cause DO drops when the algae die off and are decomposed.

Dissolved oxygen content has generally been good in Bristol Harbor, especially at sites #12

Herreshoff Dock, #1 Elks Club and #2 Bristol Harbor Inn which are closer to the mouth of the

harbor, where circulation and wind/wave mixing is better. The sites deeper within the harbor (#4

Windmill Point, #5 Mill Pond, #6 Sanroma, #7 BHYC and #8 Brito) show reduced dissolved oxygen

and generally warmer water in mid-summer. Silver Creek had potentially stressful DO levels

through much of the summer in its lower reaches. Sites #3 Silver Creek outlet and #9 Silver Bridge

(Figure 3b) reflect the influence of slower flowing water and periods of low flow in reducing

dissolved oxygen content, as well as the impact of biological activity resulting from nutrient

enrichment, which uses oxygen. With the exception of Silver Creek at Gooding Ave. (#15) the)

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Figure 3a. Bristol Harbor Sites (Arranged from Southeast to Northwest)

2012 Field Dissolved Oxygen and Temperature Data Charts

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Figure 3a (cont’d.). 2012 Bristol Harbor Dissolved Oxygen and Temperature Data Charts

(BH #3 – Silver Creek included in Figure 3b)

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Figure 3b. 2012 Dissolved Oxygen and Temperature Silver Creek Outlet and Upstream Sites

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Figure 3b (cont’d). Dissolved Oxygen and Temperature Silver Creek Outlet and Upstream Sites

upstream creek sites (#14 DaPonte Pond/Silver at Wood St., Silver Creek East #10 and West #11

Branches also reflect the influence of storm water runoff, with much more variable temperature

and DO levels, and occasion drops into stressful levels. The DO/temperature charts for these fresh

water stream sites indicate include the maximum temperature likely for cold water stream fish

such as trout. Unlike 2010, in 2011 and 2012 temperatures in these stream sites typically did not exceed the 24° C maximum temperature. However, again with the exception of site #15, DO

levels were frequently too low for trout. However, these streams likely support warm water fish.

(Figure 3b).

Mill Pond (photo by Bill Gagne from http://www.flickr.com/photos/bgags/3621742696/)

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Chlorophyll is a photosynthetic pigment found in all plants, including algae. Chlorophyll-a (chl-

a) is the most common form of chlorophyll, and is the form analyzed by URIWW to estimate the

abundance of algae in the water; the higher the chl-a level, the more algae. Because algae

need sunlight in order to convert energy into food via photosynthesis, chl-a levels tend to be

higher just below the surface of the water than at the surface. There algae are protected from

harmful ultraviolet rays but still have access to sunlight as well as to the vital plant nutrients,

nitrogen and phosphorus. Algae are essential for a healthy harbor as they form the base of the

aquatic food web. They are eaten by zooplankton (microscopic animals) and small fish, which, in

turn, are eaten by larger creatures. The abundance of healthy animals in an estuary often

depends on the amount of algae and primary productivity taking place. However, too much,

visible as algae blooms, can result in poor water clarity, unpleasant odors, and lead to anoxic

conditions particularly in bottom waters. Significant algal blooms can sometimes even result in

fish kills. The USEPA’s National Coastal Assessment (NCA) program criteria for chl-a in northeastern

estuaries are: <5 ppb (low) – good; 5 – 20 ppb (moderate) – fair; and > 20 ppb (elevated) – poor

(USEPA 2008). Bristol Harbor sites generally had low to moderate algae throughout the summer,

an indicator of a healthy aquatic ecosystem (figure 4a). However two blooms were evident at

sites #5 Mill Pond, and #6 Sanroma in 2012. Chlorophyll levels at #7 Bristol Harbor Yacht Club

were similar to those at nearby Sanroma, but only reached bloom levels later in the season.

Figure 4b shows that significant algal blooms were again experienced in several of the Silver

Creek sites (sites #3, #9, #14), requiring a change in scale for these charts from a chl-a maximum

of 25 ppb up to 50 ppb. The remaining Silver Creek sites have more flow, thus floating algae are

not able to accumulate in the same way as they can at the slower flowing sites, so we don’t see

the same overall high chl-a levels further upstream. However an algal bloom was conspicuous in

late May, at #10 Silver East, as were small blooms within the harbor itself. It’s possible that runoff

and the warming waters of spring were spurring algae growth.

Figure 4a. 2012 Bristol Harbor Sites Chlorophyll Data Charts (Arranged from Southeast to Northwest)

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Figure 4a (cont’d.). 2012 Bristol Harbor Chlorophyll Data Charts

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Figure 4a (cont’d.). 2012 Bristol Harbor Chlorophyll Data Charts

Figure 4b. 2012 Silver Creek and Upstream Sites Chlorophyll Data Charts

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Figure 4b (cont’d.). 2012 Silver Creek and Upstream Sites Chlorophyll Data Charts

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(Note: In the tables and charts that follow, Silver Creek (#3) and upstream sites (# 9-15) are

grouped at the right side of each chart, the harborside sites are arranged from southeast to

northwest with the outermost harbor sites to the left of the charts.)

Shellfish Waters Bacteria Monitoring: Fecal coliform bacteria are an indicator of fecal

contamination and potentially disease causing organisms or pathogens. The National Shellfish

Sanitation Program has established maximum acceptable fecal coliform levels at 14 colony

forming units (cfu)/100 mL for waters from which shellfish can be harvested. The standard was

designed to prevent human illness associated with the consumption of fresh and frozen shellfish,

and thus is quite conservative. Because bacteria levels can fluctuate dramatically and be

impacted by short-term intermittent, localized sources such as by seagull or goose droppings,

bacteria average concentrations are typically reported as the geometric mean. This statistical

method transforms a set of highly variable data (as bacteria can be) in order to better represent

a central tendency. Thus a single very high sample will not overwhelm routine low or below

detection values as might happen with arithmetic averaging.

Table 2. 2012 Shellfish Bacteria Indicator Data – Fecal Coliform Bacteria

10-May 7-Jun 5-Jul 10-Jul 2-Aug 6-Sep 4-Oct GEOMEAN

Site ID - - - - - Most Probable Number of Fecal coliform per 100 mL - - - - -

BH12 31 10 <10 <10 <10 148 <10 36

BH1 99 <10 10 <10 <10 530 <10 81

BH2 531 <10 10 31 10 41 <10 37

BH4 124 <10 <10 <10 10 934 <10 105

BH5 207 369 132 - 10 6867 42 175

BH6 164 <10 10 <10 20 187 <10 50

BH7 178 124 64 <10 <10 1500 <10 215

BH8 178 <10 20 <10 10 959 <10 76

BH3 794 272 3030 2282 52 342 31 363

BH9 15531 545 1376 - 62 218 <10 691

BH14 >9678 63 <10 - 20 600 213 >113

BH11 3255 63 20 - 20 284 10 78

BH10 9678.4 10 52 - <10 2628 10 168

BH15 >9678 295 86 - 1081 192 10 >139

Fecal coliform shellfish maximum = 14 cfu

Fecal coliform values at all of the in-harbor sites in 2012 were much more variable and typically

higher than in previous years (figures 5 and 6). For the first time since monitoring began, all of the

Bristol Harbor sites had geometric means that exceeded the shellfishing standards. In particular

samples collected in May were unusually high, reflecting the impact of spring storms and the

runoff associate with them, washing fecal wastes from throughout the watershed into the harbor.

September saw a similar result from a later summer storm (Table 2). Due to a malfunction in the

disinfection system at the sewage treatment plant that discharges into the harbor, the area was

closed for shellfishing from July 6th – 9th. On July 10th, additional in harbor samples were collected in

order to document conditions throughout the harbor – and confirmed the value importance of

tidal flushing to wash out contaminants and a rapid return to background levels. The Silver Creek

system had elevated levels of fecal coliform bacteria, with #15 having consistently high levels.

Overall the 2012 data continued to show that there is a significant amount of bacteria washing

into the Bristol Harbor system from throughout the watershed.

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Figure 5. 2012 Shellfish Bacteria Indicator Data – Fecal Coliform Bacteria Chart

1

10

100

1000

10000

100000

BH12 BH1 BH2 BH4 BH5 BH6 BH7 BH8 BH3 BH9 BH14 BH11 BH10 BH15

MPN

Fe

ca

l co

lifo

rm p

er 100 m

L Maximum Value

Minimum Value

GEOMEAN

2012 Bristol Harbor Fecal coliform Data

Shellfish single sample criteria = 14

Figure 6. Multi-year Shellfish Bacteria Indicator Data Chart

Swimming Waters Bacteria Monitoring: In 2004, Enterococcus spp. took the place of fecal

coliform (FC) as the standard for water quality at public beaches. It is believed to provide better

correlation than FC with human pathogens often found in sewage, particularly those associated

with gastrointestinal illnesses. Based on federal recommendations, the Rhode Island Department

of Environmental Management (RIDEM) set the primary contact (swimming) water quality

standard for salt waters at a geometric mean of 35 enterococcus/100 mL for five or more

samples. Geometric means for non-swimming fresh waters is 54 enterococcus/100 mL. To be

more responsive to short term events, the Rhode Island Department of Health (RIHealth) adopted

a single sample standard for swimming advisories at designated beaches. For salt waters, the

RIHealth beach standard is 104 most probable number (mpn - a statistically based reporting

method) enterococci/100 mL, and 61 mpn for fresh water.

In 2012, with the exception of May and September, Enterococci values were considered safe for

swimming (Table 3), particularly for the sites in the outer harbor. However, Mill Pond (5) exceeded

safe swimming values 4 out of 6 times. The remainder of the harbor sites had seasonal geometric

means within the range considered safe for swimming, but had periods when swimming would

not have been a good idea (figures 7 and 8). Having enterococci levels that exceeded

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swimming criteria at all of the harbor sites for two collections was unusual and warrants

continued monitoring. As with the fecal coliform, the Silver Creek systems had elevated

enterococci levels throughout most of the season. Fortunately there is little to no swimming at

these sites, but these results confirming the creek and its watershed are likely a significant source

of bacteria to the harbor.

Table 3. 2012 Swimming Bacteria Indicator Data: Enterococcus Bacteria

10-May 7-Jun 5-Jul 10-Jul 2-Aug 6-Sep 4-Oct GEOMEAN

Site ID - - - - - Most Probable Number of Enterococci per 100 mL - - - - - -

BH12 192 10 20 <10 10 272 <10 22

BH1 531 <10 10 <10 10 428 <10 17

BH2 2005 <10 10 <10 <10 85 20 18

BH4 659 <10 <10 20 <10 1850 <10 30

BH5 1298 420 187 - <10 11199 <10 1034

BH6 238 <10 10 <10 20 246 <10 15

BH7 384 40 10 <10 <10 3654 64 57

BH8 429 <10 <10 <10 <10 2187 124 104

BH3 14136 2723 776 591 <10 6896 384 1898

BH9 19863 426 3448 - 1274 2162 122 1463

BH14 >24196 250 10 - 74 7746 98 >264

BH11 22030 185 122 - 110 1042 30 346

BH10 3921.6 109 63 - 52 1789 96 249

BH15 8305 96 75 - 480 1248 128 408

Enterococcus salt water swimming single sample maximum = 104 MPN (35 geomean)

Enterococcus fresh water single sample swimming maximum = 61 MPN (33 geomean)

Figure 7. 2012 Bristol Harbor Sites – Enterococci Bacteria Data Chart

1

10

100

1000

10000

100000


MPN

En

tero

co

cc

i pe

r 100 m

L Maximum Value

Minimum Value

GEOMEAN

2012 Bristol Harbor Enterococci Data

Swimming single samplecriteria = 104Swimming single

samplecriteria = 61

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Figure 8. 2009-2012 Bristol Harbor Sites – Enterococci Bacteria Chart

Bristol Harbor Nutrients, 2009 – 2012:

Figure 9. Nutrients in the Coastal Zone (from http://kodu.ut.ee/~olli/eutr/html/htmlBook_78.html)

Nitrogen is a natural

and essential part of all

marine ecosystems, as it

is required for the

growth of algae or

phytoplankton, the

primary producers that

form the base of the

harbor’s food web

(USEPA 2008.) Excess

nitrogen (N) adversely

affects water quality

and degrades habitat,

ultimately impacting a

wide range marine

organisms including fish

and shellfish (figure 9).

Nutrient overloading in

marine ecosystems

over-stimulates the

growth of algae. Too

much algae blocks

sunlight to eelgrass, reducing the quality and area of this valuable nursery habitat and feeding

ground. In addition, living and dying algae consume oxygen, leading to hypoxic (low oxygen)

and anoxic (no oxygen) conditions. This process of water quality decline creates a chain

reaction of negative impacts known as eutrophication. Poor water clarity, bad odors, stressed

marine organisms and even fish kills are all symptoms of eutrophic conditions marine organisms

including fish and shellfish (Howes et al. 1999).

Total nitrogen, which includes both organic nitrogen (the N found in live, dead or decomposing

plants and animals) as well as inorganic (the N that is dissolved into solution or bound to

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sediments, etc.) is widely used by scientists as an indicator of eutrophication or nutrient

enrichment in marine waters. Levels below 350 parts per billion (ppb) are characteristic of low

nutrient waters, while values above 600-700 ppb indicate nitrogen enrichment (Howes et al.

1999). Total nitrogen (TN) levels in most of the Bristol Harbor sites have been at low to moderate

levels throughout most of the seasons since 2009, with the exception of Silver Creek outlet (3). In

general annual TN averages have decreased since monitoring began (figure 10a). The TN levels

in the upstream tributaries (9-15) continue to be very high, on average more than double the

harbor sites (10b). These data are particularly interesting because TN at the two downstream sites

(3 and 9) are lower than upstream sites and continue to decline. Total nitrogen at the upstream

sites (10 - 15) are quite high, with levels increasing are you move upstream. This suggests that

there may be areas downstream from those stream segments that act as nitrogen sinks, where N

is trapped and converted to its atmospheric form of nitrogen gas (N2 or N2O) by microbes,

keeping it from flowing downstream. Protecting and enhancing these wetland areas could help

to reduce the impact from stormwater runoff. Maintaining the expanded monitoring upstream

on Silver Creek would be important for tracking changes in incoming nitrogen, and perhaps to

identify potential nitrogen sinks.

Figure 10a. Bristol Harbor Annual Total Nitrogen Data Chart

20

220

420

620

820

1020

1220

1420

BH13 BH12 BH1 BH2 BH4 BH5 BH6 BH7 BH8 BH3 BH9 BH14 BH11 BH10 BH15

pp

b T

ota

l N

2009 2010 2011 2012

2009 - 2012 Average Annual Total Nitrogen

Nutrient enriched above 600-700 ppb

1658 1709

Figure 10b. Bristol Harbor 2012 Total Nitrogen Data Chart

20

220

420

620

820

1020

1220

1420

1620


10-May 7-Jun 5-Jul

2-Aug 6-Sep 4-Oct

2012 Bristol Harbor Total Nitrogen Data

(Minimum Detection Limit = 20 ppb)

pp

b T

ota

l-N

Nutrient enriched above 600-700 ppb

Greater than 1670 ppb

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Ammonia-nitrogen (NH4-N) is the most reactive form of N in aquatic systems. It is soluble, readily

adheres to soils and sediments, and is converted to nitrate by microbes when oxygen is present

through a process called nitrification. Nitrification requires a substantial amount of oxygen and

carbonate, thus can reduce both DO levels and pH slightly. In excess, ammonia-nitrogen can be

toxic, particularly to early life stages of a variety of aquatic species. The level at which ammonia

becomes lethal is dependent on water temperature, pH, and salinity so site specific criteria are

applied (see http://www.dem.ri.gov/pubs/regs/regs/water/h20q09a.pdf for more information).

Figure 11a. Bristol Harbor Annual Ammonia-Nitrogen Data Chart

20

80

140

200

260

320


pp

b A

mm

on

ia-N

2009 2010 2011 2012

2009 - 2012 Average Annual Ammonia-Nitrogen

(minimum detection limit = 20 ppb)

In general, given the conditions in Bristol Harbor, chronic exposure critical ammonia level would

be approximately >650 ppb, and much higher than the levels found at any Bristol Harbor site.

With the exception of Silver Creek (3) ammonia levels were very low (near the URIWW lab limit of

detection) for most of the 2009 season (Figure 11a). In 2010, most locations had significantly

higher NH4-N levels, in particular Silver Creek and upstream. In 2011, ammonia levels were

generally less than in 2010, but still higher than they had been in 2009. By 2012, ammonia levels at

most of harbor sites remained higher than when monitoring began. Interestingly, NH4-N levels in

Silver Creek (3) have declined to levels consistent with other harbor sites. Typically, NH4-N starts

out low each season, peaking in mid-summer or early autumn, as illustrated by the 2012 monthly

results (figure 11b).

Figure 11b. Bristol Harbor 2012 Ammonia-Nitrogen Data Chart

15

65

115

165

215

265

315


10-May 7-Jun 5-Jul2-Aug 6-Sep 4-Oct

2012 Bristol Harbor Ammonia-Nitrogen Data(Minimum Detection Limit = 15 ppb)

pp

b A

mm

on

ia-N

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Nitrate + nitrite-nitrogen (NO3-N) is also a soluble form of N, and is readily taken up and used by

algae and submerged vegetation during the summer growing season. When oxygen is absent

(anoxic conditions), bacteria convert nitrate-N to gaseous N (N2 or N2O) through a process called

denitrification, which removes N from the soil-water environment. In 2009 NO3-N levels were

typically near or below the 10 ppb minimum detection level for most sites, except the Silver Creek

sites. Results for the harbor sites were relatively consistent since 2009, except for #5, which had

much higher levels in 2012 than in the pasts. Figure 12a shows the comparatively high levels in the

upstream Silver Creek sites (9-15). Nitrate + nitrite-N levels in these sites were high throughout most

of the monitoring 2012 season, resulting in averages of 481 - 1296 ppb (figure 12b).

Figure 12a. Bristol Harbor Annual Nitrate + nitrite-Nitrogen Data Chart

Figure 11b. Bristol Harbor 2012 Nitrate + nitrite-Nitrogen Data Chart

5

205

405

605

805

1005

1205


10-May 7-Jun 5-Jul

2-Aug 6-Sep 4-Oct

2012 Bristol Harbor Nitrate+nitrite-Nitrogen Data


pp

b N

itra

te+

nitrite

-N


Dissolved Inorganic Nitrogen (DIN): The National Coastal Assessment program uses dissolved

inorganic nitrogen (DIN), which includes ammonia-N (NH4-N) and nitrate + nitrite-N (NO3-N), as a

key component in its coastal conditions assessment. For northeastern estuaries, DIN levels <100

ppb are considered good, 100 – 500 ppb considered fair, and > 500 ppb considered poor water

quality (USEPA 2008). With the exception of sites 5 and 3, 2012 DIN levels were higher than in 2011

but lower than the peak values (figure 13a). All harbor sites had annual DIN levels within the

moderate or fair level during the latter part of 2012. Ammonia-N is the major component of DIN in

the harbor sites, with nitrate + nitrite –N dominant in the Silver Creek sites (figure 13b).

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Figure 13a. Bristol Harbor Sites – Annual Dissolved Inorganic Nitrogen Data Chart

10

110

210

310

410

510

610

710

810

910

1010


pp

b D

IN

2009 2010 2011 2012

2009 - 2012 Average Annual Dissolved Inorganic Nitrogen (DIN)(NO3-N + NH4-N)

Elevated DIN - Poor

Moderate DIN - Fair

1273 1338

Figure 13b. Bristol Harbor Sites – 2011 Dissolved Inorganic Nitrogen Data Chart

10

110

210

310

410

510

610

710

810

910


10-May 7-Jun 5-Jul

2-Aug 6-Sep 4-Oct

2012 Bristol Harbor Dissolved Inorganic Nitrogen (DIN) Data

(NO3-N + NH4-N)

Elevated DIN level - Poor

Moderate DIN level - Fair

pp

b D

IN


Phosphorus: In most estuaries such as Bristol Harbor, nitrogen is the primary nutrient that controls

algal and plant growth. However phosphorus (P) is also essential for life, and in salt water

environments P levels are considered in relationship to N levels. If large amounts of nitrogen are

available, with adequate phosphorus present, algal blooms can occur. Phosphorus was

analyzed as the total form which includes P bound in particulate (organic and inorganic) matter

and soluble or dissolved forms which are readily used by algae. Dissolved inorganic P (known as

dissolved P (DIP) or orthophosphate P) has been analyzed in Bristol Harbor since 2010.

Total Phosphorus: Except for the Silver Creek sites, annual total phosphorus (TP) values have

generally been below 100 ppb, the level of concern, (Figure 14a). Total phosphorus levels in 2012

were generally higher than in previous years, but with the exception of #6 (Sanroma) the harbor

sites were below the level of concern, similar to TN levels. Total phosphorus levels at Silver Creek

(#3) remain high, but are declining, while upstream sites are generally remaining relatively stable.

The 2012 TP values followed a similar pattern as did the bacteria (highest in May and September),

suggesting the strong influence of stormwater on TP values in the harbor and its watershed (figure

14b).

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Figure 14a. Bristol Harbor Annual Total Phosphorus Data Chart

3

23

43

63

83

103

123

143


pp

b T

ota

l P

2009 2010 2011 2012

2009 - 2012 Average Annual Total Phosphorus 172

Figure 14b. Bristol Harbor 2011 Total Phosphorus Data Chart

4

54

104

154

204

254


10-May 7-Jun 5-Jul2-Aug 6-Sep 4-Oct

2012 Bristol Harbor Total Phosphorus Data


pp

b T

ota

l-P

682

Dissolved Phosphorus: Dissolved inorganic phosphorus (DIP) is the portion of P readily available

for use by aquatic organisms, and is analogous to DIN. The National Coastal Assessment program

uses DIP as a key component in its coastal conditions assessment. DIP surface concentrations <10

ppb are considered good, 10-50 ppb considered fair, and >50 ppb considered poor.

Figure 15a. Bristol Harbor Annual Dissolved Phosphorus Data Chart

3

23

43

63

83

103

123

143


pp

b D

isso

lve

d In

org

an

ic P

2010 2011 2012

2010 - 2012 Average Annual Dissolved Phosphorus (DIP)

(not analyzed in 2009)

Elevated DIP - Poor

Moderate DIP - Fair

22

Since 2010 with exception of the Silver Creek outlet site (3) the Bristol Harbor sites were generally

within the fair range for DIP (Figure 15a). Silver Creek DIP levels fell to fair levels for the first time in

2012, which was particularly interesting since most of the other harbor sites had generally higher

DIP in 2012 (figure 15b). Continued monitoring will be important to ascertain whether the

apparent increases in DIP were associated with weather patterns in 2012, or part of an overall

trend.

Figure 15b. Bristol Harbor 2011 Dissolved Phosphorus Data Chart

3

23

43

63

83

103

123


10-May 7-Jun 5-Jul 2-Aug 6-Sep 4-Oct

2012 Bristol Harbor Dissolved Inorganic Phosphorus (DIP) Data

(Minimun Detction Limit = 3 ppb)

Elevated DIP level - Poor

Moderate DIP level - Fair

pp

b D

IP

682

Hats off to these outstanding water quality volunteers… Bob Aldrich, Joe Arruda, Denise

Arsenault, Stephen Barker, Christine Bean, Kevin Beauleiu, Chip Cavallaro, Janet Christopher,

Susan Donovan, Bob Hamel, Rob & Gwen Hancock, Barbara Healy, Mike Kotuby, Keith Maloney,

Valerie Malone, Katia & Marguerite Moran, Kai Norden, Mike Oliver, Gabrielle Passerello, Andrea

Pereira, Gregory Rego, Ethan Tucker, Simone Verria, and Justin Vincente. These outstanding

individuals got up very early each Thursday morning throughout the 2012 season, rain or shine,

working in teams to monitor their site.

… and especially to their indomitable local coordinators (and fellow water quality monitors):

Bob Aldrich and Keith Maloney. Each season these gentlemen work tirelessly to recruit volunteers,

coordinate training sessions, keep in touch with everyone, ensure that the local volunteers had all

the necessary equipment, supplies and any other resources they need and act as couriers,

delivering samples on a monthly basis with cheery greetings to the URI Watershed Watch staff

and student interns. Please see the Save Bristol Harbor website

(http://www.savebristolharbor.com/) to learn more about their efforts or how you can help.

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References:

Howes, Brian, Tony Williams and Mark Rasmussen, 1999. BayWatchers II Nutrient related water

quality of Buzzards Bay embayments: a synthesis of Baywatchers monitoring 1992-1998

http://www.savebuzzardsbay.org/bayinfo/publications/BaywatchersII/baywaters-pages3-

34.pdf.

Olli, Kalle. 2004. Drainage basin nutrient inputs and eutrophication: an integrated approach.

eBook, Universesity of Tartu, Institute of Botany and Ecology, Tartu, Estonia -

http://kodu.ut.ee/~olli/eutr/html/htmlBook.html

National Oceanic and Atmospheric Administration’s (NOAA) Ocean Service Education

Monitoring Estuaries website

http://oceanservice.noaa.gov/education/kits/estuaries/estuaries10_monitoring.html

Russian River Pathogen Project (RRPP) Working Draft Report, Updated 01/28/2008

http://rrpp.ice.ucdavis.edu/node/7

Save Bristol Harbor website http://www.savebristolharbor.com

United States Environmental Protect Agency (EPA), 2008. National Estuary Program Coastal

Condition Report Introduction

http://www.epa.gov/owow/oceans/nepccr/pdf/nepccr_intro.pdf

University of Rhode Island (URI) Office of Marine Programs’ Discovery of Estuarine Environments

website http://omp.gso.uri.edu/ompweb/doee/science/intro.htm)

University of Rhode Island Watershed Watch website (includes monitoring manual, data, fact

sheets, and links to local, regional and national information) http://www.uri.edu/ce/wq/ww

Students learning how to plant marsh plants in order to restore vital coastal habitat

http://www.savebuzzardsbay.org/bayinfo/publications/BaywatchersII/baywaters-pages3-34.pdf

http://www.savebuzzardsbay.org/bayinfo/publications/BaywatchersII/baywaters-pages3-34.pdf

http://kodu.ut.ee/~olli/eutr/html/htmlBook.html

http://oceanservice.noaa.gov/education/kits/estuaries/estuaries10_monitoring.html

http://www.savebristolharbor.com/

http://www.epa.gov/owow/oceans/nepccr/pdf/nepccr_intro.pdf

http://omp.gso.uri.edu/ompweb/doee/science/intro.htm

http://www.uri.edu/ce/wq/ww

24

Appendix A. Additional Water Quality Results

2012 pH Data:

10-May 7-Jun 5-Jul 2-Aug 6-Sep 4-Oct MEAN

- - - - - - - - - - - - - - - Standard pH Units - - - - - - - - - - - - - - -

BH12-Herreshoff 8.0 8.0 7.8 7.6 7.8 7.8 7.8

BH01-Elks Club 7.7 7.7 7.6 7.9 7.7 7.7 7.7

BH02-Bristol Harbor Inn 7.7 8.0 7.7 7.8 7.8 7.7 7.8

BH04-Windmill Pt 7.7 8.0 7.9 7.9 7.7 7.7 7.8

BH05-Mill Pond 7.5 7.6 7.7 7.7 7.1 7.5 7.5

BH06-Sanroma 7.8 8.1 7.7 7.6 7.5 7.6 7.7

BH07-Bristol Yacht Club 7.7 8.1 7.9 7.8 7.7 7.7 7.8

BH08-Brito Dock 7.8 8.1 7.9 7.9 7.7 7.8 7.9

BH03-Silver Creek 7.8 7.4 7.3 7.8 7.1 7.1 7.4

BH09-Silver Bridge 7.8 7.6 7.5 7.3 7.1 7.2 7.4

BH14-DaPonte/Wood St. 7.6 8.2 8.9 6.9 6.9 7.1 7.6

BH11-Silver West 7.7 7.4 7.0 6.7 7.2 7.1 7.2

BH10-Silver East 7.9 7.6 7.5 7.1 6.8 7.0 7.3

BH15-Silver Gooding Ave. 7.3 7.5 7.5 7.0 7.1 7.2 7.3

Bristol Harbors Sites

2009 – 2012 pH Data Chart

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5

6

7

8

9

10


pH S

tand

ard

Uni

ts

2009 2010 2011 2012

2009 - 2012 Average Annual pH

Expected Normal pH Range

2012 Salinity Data:

5/12 5/26 6/9 6/23 7/7 7/21 8/4 8/18 9/8 9/22 10/6 Mean

Site # (ppt)

BH12 30 15.5 30 30 31.5 30 33 30 30 30 34 29.5

BH1 30 30 - 30 30 30 32.5 30 30 32 33.5 30.8

BH2 30 30 - 30 32 30 33.5 30 31 31 34 31.2

BH4 30 - 30 30 30.5 30 33.5 30 30 32 34 31

BH5 28 30 - 30 29 30 34 - 12 30 31.5 28.3

BH6 30 30 30 30 28.5 30 31.5 30 30 30 33.5 30.3

BH7 30 30 30 30 30.5 30 34 30 29 30 34 30.7

BH8 32 - 30 30 31 30 32.5 30 29 30 34 30.9

BH3 0 5 - 25 26.5 30 33 16 2 10 7.5 15.5

BH9 0 0 - 2 8 0 9.5 5 0 0 2 2.65

BH14 - - - - 0.5 - 1 - - - - 0.75

BH11 - - - - 1 - 2 - - - - 1.5

BH10 - - - - 2 - 2 - - - - 2

BH15 - - - - 1 - 1.5 - - - - 1.25

- - - - - - - - - - - - - - - - parts per thousand (ppt) Salinity - - - - - - - - - - - - - - - - - - -

university of rhode island linda t green...

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