Decision Makers WorkshopLandscape Solutions: Strategies for effective stormwater management and fertilizer use

Newburyport, MA 978-499-0601

Providence, RI 401-272-1717

Speaker Profile:Rich Claytor, Principal Engineer at HW, has more than 28 years of practical experience in civil and water resource engineering. Rich has specific expertise in watershed planning and management; stormwater

management practice design, policy development and master planning; stream and river geomorphology; water supply and wastewater conveyance design; land use planning, site design; drainage and erosion/sediment control design. He has authored a variety of publications on stormwater design and implementation and presented in more than 100 training workshop and conferences over the last 20 years.

Sandwich, MA508-833-6600

Horsley Witten GroupSustainable Environmental Solutions

Boston, MA857-263-8193

www.horsleywitten.com

March 20, 2013 - UMass Cranberry Station, East Wareham

Workshop Packet Contents:• Restoring the Ponds in Roger Williams

Park Summary Plan• Summary of Watershed Management

Plan for Rhode Islands Salt Ponds• Summary of Pleasant Bay Fertilizer

Management Plan Final Report

Stormwater Management at Taunton Mill River Park

. .

Summary Plan for Restoring the Ponds in Roger Williams Park

. .

Restoring the Ponds in Roger Williams Park:

Summary Plan

1.0 Introduction

Since the first plan for Roger Williams Park was

developed in 1878 by landscape architect

Horace Cleveland, the Park ponds have been

considered essential visual and recreational

elements in the Park’s design. Over the years,

the ponds have provided boating opportunities,

a place to fish, a home for wildlife, and a visual

refuge for urban dwellers looking for relief from

crowded city streets.

The Park ponds, however, have been suffering from algae problems, aquatic weed growth, and

sedimentation from road sand for many decades. In 1982 Park officials spent several hundred thousand

dollars to dredge 3 of the ponds in the pond system, but it didn’t solve the algae problem in the ponds

as phosphorous-laden storm water and road sand continued to flow unabated into the ponds. The

ponds were first listed in the Rhode Island Department of Environmental Management’s (RIDEM)

impaired water bodies list in 1992. The algae and aquatic weed growth in the ponds has been so severe

in the last 10 years, that RIDEM in 2007 released a report, Total Maximum Daily Load Report (TMDL), to

analyze 9 ponds in Rhode Island with the most challenging phosphorous problems. The Roger Williams

Park pond system was one of the pond systems highlighted for its worsening problems.

In 2010 with the urging and cooperation of the

Narragansett Bay Estuary Program (NBEP), the Parks

Department applied for and received an EPA Region

1 matching grant to comprehensively examine the

pond’s pollution problems, to suggest remedial

options, and to provide a plan for restoring the

ponds’ water quality. With the assistance of a

Technical Steering Committee, the firm of the

Horsley-Witten Group (HW) was selected to develop

a Water Quality Management Plan for the Park

ponds. The Committee has helped guide the work of

HW which began in July 2011.

The project Steering Committee established the following goals for the

pond restoration project:

Roger Williams Park Ponds Restoration

Project Goals

The first of these items—water quality restoration—is central to the

project. The HW firm undertook extensive investigations and completed

a water quality model and draft document for restoration of the ponds.

As a result of the HW work, it became clear that a significant reduction in

phosphorus pollution to the Ponds is necessary to achieve water quality

improvement. The sources of phosphorus include atmospheric

deposition, internal recycling within the Ponds, loading from waterfowl,

and stormwater runoff from upland sources. The City and Steering

Committee, therefore, established the following targets for phosphorus

pollution reduction in the Ponds, in order to improve water quality,

habitat quality and aesthetics:

Water Quality Restoration—Phosphorus Reduction Targets

Roger Williams Park

Ponds Restoration Project

Technical Steering Committee

Providence Parks & Recreation

Narragansett Bay Estuary Program

U.S. Environmental Protection Agency Region 1

US EPA Atlantic Ecology Division

RI Coastal Resources Management Council

RI Department of Health

RI Department of Environmental Management

RI Department of Transportation

Save the Bay

Save the Lakes

US Fish & Wildlife Service

USDA Natural Resources Conservation Service

University of Rhode Island Watershed Watch

RI Bass Federation

Environmental Justice League of Rhode Island

Serve Rhode Island

Pawtuxet River Authority

RI Natural History Survey

Urban Ponds Procession

Improve water quality, habitat, and biodiversity within the

ponds

Improve the overall environmental quality and user experience

of the Park

Identify health risks associated with fish consumption; increase

public awareness as warranted

Foster watershed awareness and environmental stewardship

among Park users and surrounding residents through a public

outreach campaign

Reduce phosphorous loadings to the ponds by 20% in five years

Reduce phosphorous loadings to the ponds by 42% in ten years

Over the long term, 20-25 years, reduce phosphorus loadings

by up to 73%, a reduction which RI Department of

Environmental Management suggests would allow the Park

ponds to achieve a water quality that would be significantly

reduce seasonal algae and aquatic weed growth

2.0 Background

With the exception of Deep Spring Lake,

the Park ponds are man-made, and

consist of a series of seven interconnected

ponds. As the Park was developed in the

latter years of the 19th century,

Mashapaug Brook that ran from

Mashapaug Pond was used as the primary

water source to create the Park ponds.

This former location of the Brook in area

now constituting the Park is shown above.

The Brook was dammed near present day

Park Avenue at the southern end of what

is now Elm Pond. In conjunction with

considerable dredging that was done by

the hands of many immigrant laborers

over many years, several of the ponds

were literally carved out of the landscape.

Bridges were built to allow the ponds to

flow continuously from one to the other,

from Roosevelt Pond near the Casino to

Elm Pond near the Park Avenue entrance.

The general pattern of flow through the Park ponds is from the southern end of Roosevelt Lake where a

48 inch diameter pipe from Mashapaug Pond is located to the dam at the southern end of Elm Pond.

Once the water leaves the Park, it flows into Bellefont Brook into the Pawtuxet River and eventually to

Narragansett Bay.

Roger Williams Park Ponds Characteristics Pond Average Depth Area Direction of Flow (feet) (Acres) Roosevelt 1.3 3.8 West to East then North to South

Willow 2.0 3.4 South to North and North to South

Polo 2.3 3.6 South to North

Pleasure 2.6 18.6 West to East

Edgewood 3.0 19.3 North to South

Cunliff 4.3 32.3 North to South

Elm 4.3 21.7 North to South

Roger Williams Park Pond System

3.0 The Park Ponds are in Trouble Today

For almost six months a year the Park ponds appear as envisioned when the Park was built—free of

algae and weeds and reasonably normal in color and clarity. But those six months are generally from

November to April when the ponds are not actively used and overall park visitation is low. Beginning

generally in May every year, the shallow Park ponds began to heat up and to display a pea soup green

color culminating with floating algae and acres of weeds in July-October, this is known as eutrophic or

hypereutrophic conditions. Scientists typically look at a few key parameters to help assess water quality

conditions, including Chlorophyll a, total phosphorus concentration, and Secchi dish depth (a measure of

water clarity). As seen below, water quality data reflects the extent of water quality degradation in the

ponds. Even the casual Park visitor, without the benefit of scientific water quality data for the ponds,

can visually see the water quality degradation in the Park ponds.

Summary of Water Quality Data for Roger Williams Park Ponds (URI Watershed Watch 1993-2012) Water Quality

Parameter

Typical Threshold

for Eutrophic Conditions

Average Value in Ponds by Year

Pleasure Lake Roosevelt Lake Cunliff Lake

Elm Lake

19

93

19

94

20

01

20

02

20

05

20

12

19

93

19

94

20

12

20

03

20

12

20

05

20

12

Chlorophyll a (ppm)

7.2 to 30 22 28 20 46 57 55 17 26 31 54 55 56 58

Total P (ppm)

25 to 65 85 105 76 64 140 100 65 69 76 120 87 97 82

Secchi Depth (ft)

6.5 to 2.5 5.2 4.6 3.0 2.0 1.6 2.6 5.2 5.2 1.6 2.3 2.6 2.0 3.0

Red Font = value exceeds outside range of Eutrophic Threshold

Why should we care about the poor water quality in the Park ponds?

The degraded water quality condition of the ponds in the summer and early fall months is troublesome

for many reasons:

The boating experience on the ponds is diminished

Biodiversity, particularly fish species, in the ponds is reduced

Nearby shoreline activities, such as picnicking and gatherings, are unpleasant

The overall perception of the park as an enjoyable family place to visit is negatively altered

Finally, Roger Williams Park is the primary recreational area for thousands of Providence

families who do not have access to the state’s south county beaches and the restoration of

the Park’s water resources is a matter of environmental justice.

What is causing the water quality problems in the Park ponds?

The answer to that question is both simple and complex. To properly understand what is happening to

the ponds, it is useful to remember that the ponds are man-made. They are not natural geologically

formed deep lakes that you might find in western and northern Rhode Island. And because the Park

ponds are shallow, the ponds heat up quickly when the summer ambient air temperatures increase.

The shallow warm lakes when initially constructed probably did not exhibit today’s water quality

problems. The Park when it was built in the 1880’s and 1890’s was at the southern end of Providence

largely surrounded by vacant land. As the city’s population grew, the areas around the park were

developed into dense residential neighborhoods. Thousands of acres of vacant land became houses,

businesses, streets, sidewalks, driveways, and parking lots.

And when it rained, city engineers

provided these nearby

neighborhoods with storm

drainage systems with storm water

outfalls, many of which drained

into the Park ponds. Even the

Park’s principal source of flow—the

Mashapaug Brook—was at some

point channeled into a large storm

pipe before it enters Roosevelt

Pond. Throughout the 20th

century, park engineers also

drained Park roads and parking lots

into a storm drainage system which

today flows into the Park ponds via

many outfall pipes.

Not only did the areas around the Park develop, but the area around Mashapaug Pond and its feeder

ponds, Spectacle Pond and Tongue Pond, also were urbanized. Mashapaug Pond was relatively pristine

when its outflow from the pond, Mashapaug Brook was used to form the Park Ponds. Indeed, as late as

the early 20th century, Mashapaug Pond was a source of block ice for hundreds of Providence homes.

The accompanying aerial photograph shows the Park’s two main watershed areas—areas that are the

sources of storm water flowing into the Park ponds. The extent of development in the two watersheds

is pretty dramatic. And the graphic below illustrates the relationship of the Park ponds to its

watersheds.

Upper Watershed

Lower Watershed

Once dependent solely on Mashapaug Brook for its water source, the Park ponds became the

convenient receptacle for storm water from hundreds of acres of two nearby watersheds every time it

rained. This storm water is not clean. Anything on the impervious surfaces that drains into the Park

ponds—dirt, bird waste, pet waste, car chemicals, fertilizer, trash—is carried by the storm water into the

Park ponds.

Tongue Pond

Watershed

Water

Spectacle Pond

Watershed

Mashapaug Pond

Watershed

Tongue

Pond

Spectacle

Pond

Mashapaug

Pond

Roger Williams

Park Ponds

Park Property

Watershed

Adjacent

Neighborhood

Watershed

Roger Williams Park Ponds Watersheds

Upper Watershed

Lower Watershed

The chemical culprit of particular concern in the storm water flowing into the

Park ponds is phosphorous.

A modest increase in phosphorous in a water body can, under the right conditions, set off a chain of

undesirable biological events that can accelerate algal blooms, undesirable plant growth, depletion of

dissolved oxygen, and the death of oxygen dependent fish. This process is known as eutrophication

which may take centuries to occur in undeveloped areas, but which in the Park ponds is accelerated by

the storm water entering the ponds after every rain event. The shallow warm Park ponds provide a

perfect situation for the significant amounts of phosphorous entering the ponds to stimulate algal

blooms and plant growth. See graphic below for the sources of phosphorous in the Park ponds.

Watershed Areas Upper—977 acres Lower—649 acres

Total—1,626 acres

Cranston/Providence

Boundary

Sources of Phosphorous  

in the Roger Williams Park Ponds 

 

 

 

 

                                                                         

 

 

 

 

As seen above, a major source of phosphorous in the ponds is not just the drainage system, but the number of Canada geese that have taken up residence in the Park.  For decades Canada geese migrated south and stopped along their journey in the Park ponds.  Once the ponds began to freeze, the geese would continue their journey south.  Because of relatively recent climate changes, however, the Park ponds no longer consistently freeze in the December‐March months.  Gradually, large numbers of geese simply wintered over in Roger Williams Park.  As the resident geese population increased, park visitors unfortunately began to fed them bread from home.  And feeding the geese bread continued throughout all months of the year.  

While well‐intentioned, public feeding of the geese in the Park is misguided and as recently as July 2012 resulted in over 700 resident geese living in the Park.  Unknown to most of the Park visitors, the gaggles of geese in the Park have been an environmental and public health nightmare for the Park because of the sheer volume of fecal matter produced by the geese on park lawns and in the park ponds.  Park officials began a comprehensive geese management strategy in the last 6 months of 2012, including signs instructing the public not to feed the geese.  This short‐term effort has drastically reduced the geese population.in the Park to approximately 60‐75 birds. 

Upper Watershed Storm Water 

 (360 lbs/yr) 

Roger Williams Park Ponds 

(128 lbs/yr) 

Atmospheric Deposition 

(64 lbs/yr) 

Lower Watershed Storm Water 

(216 lbs/yr) 

Roger Williams Park Waterfowl 

(154 lbs/yr)

3.0 What Can Be Done: Best Management Practices

The Horsley-Witten (HW) study of the Park ponds outlines scores of potential remedies to reduce

phosphorous loadings entering the ponds. The study recommends everything from cleaning the street

catch basins more frequently to re-directing existing storm water flows to educating nearby

homeowners to reduce pollution that washes into the Park ponds.

Outlined below are some of the principal categories of best management practices that potentially may

improve the water quality of the Roger Williams Park ponds:

4.1 Structural Storm Water System Changes

Storm Water System Retro Fits—the HW study examined about 30 places in the Park where

the existing storm water pipes could be diverted and re-engineered to enable storm water

to flow into bio-retention vegetated areas and swales before entering the groundwater into

the ponds. This technique essentially allows the storm water to be intercepted and to be

treated before it enters the pond system. The graphic below illustrates a typical storm

water treatment design. The picture below shows a bio retention area being constructed

near the Carousel which now drains a major portion of the Carousel parking lot.

Pavement Reduction—A very basic method

for reducing storm water pollution in the ponds is to reduce the amount of impervious

surfaces—primarily parking lots and roadways—in the Park to reduce the amount of storm

water flow. While the Park has many stretches of wide roads that could be narrowed, this

type of structural change needs to consider parking and traffic issues very carefully. Thus,

Park staff will examine where pavement can be reduced at a reasonable cost without

affecting normal Park use. The current storm water retro fit project along Roosevelt Pond

involves the removal of almost 40,000 sq. ft of road area.

Curb Removal—Roger Williams Park, unlike the large state parks in Rhode Island, has miles

of curbing along the sides of its roads. This curbing is a legacy of work done by the Works

Progress Administration in the 1930’s and was a well intentioned effort to channel storm

water into catch basins to flow into the ponds. There are lots of opportunities in the Park to

selectively remove curbing to allow storm water to flow into existing grass areas and to be

absorbed into groundwater.

Disconnecting Building Down Spouts—Another storm water practice implemented in

Providence in the early 20th century was to have building down spouts connect directly into

underground drainage lines that then directed storm water into the street drainage system.

This practice also occurred in the Park

and in the watersheds draining into

the Park. The roof areas in the Park

total over 100,000 sq. ft and thus

send a lot of storm water into the

ponds. These down spouts can be

disconnected relatively easily from

the underground pipes and then the

down spouts can be altered to divert

the storm water into adjacent

planting areas. This has been

successfully done in a demonstration

at the Botanical Center already as

seen in the accompanying photo.

This practice also offers significant potential in the upper and lower watersheds where

neighborhoods, according to the HW study, have generally 50-60% of houses with down

spouts directly connected to underground storm water pipes.

4.2 Non Structural Practices

While some of the above structural practices will involve considerable capital costs, there are scores of

non structural practices, much less costly, that can be implemented in the Park and in the nearby

watersheds draining into the Park to reduce storm water loadings.

Operations and Maintenance Practices—Daily operations in Roger Williams Park and the

abutting watersheds can be altered and adjusted to reduce storm water pollution. Here are

the most significant practices that should be considered:

--Catch Basin Cleaning: Catch basins in the street “catch” storm water flowing on the street

and then through gravity flow discharge the flows from the catch basin through a pipe into a

nearby water body. As seen in the accompanying sketch, catch basins are designed to settle

out solids before the storm water flows into the discharge pipe. These solids are loaded

with nutrients and thus catch basins can potentially be a significant method for reducing

storm water pollution flowing into the Park ponds, if the catch basins are periodically

cleaned of the settled solids.

If the catch basin solids are not cleaned in a timely manner,

they eventually fill up the catch basin and storm water

events flush the solids into the discharge pipe into the

nearby water body. Roger Williams Park has approximately

45 catch basins and there are perhaps a few hundred in the

upper and lower watersheds outside of the park. The Parks

Department does not have its own vacuum truck to clean

out catch basins—it depends on an already strapped

Providence Department of Public Works (DPW) to

periodically clean Park catch basins as well as the catch

basins in the upper and lower watersheds. This catch basin

cleaning does not consistently occur because does not have

the resources to clean approximately 20,000 catch basins

throughout the City.

Park officials are examining how to become self-sufficient

for catch basin cleaning.

--Street Sweeping: One way to reduce the amount of solids and trash on Park and

watershed streets from flowing into the storm water drainage system is to sweep the

streets more frequently. The Parks Department does not own a street sweeper and

depends on Providence DPW to sweep the 10 miles of roads in Roger Williams Park twice a

year. Park officials need to figure out how to supplement the DPW services with private

vendors or how to contract DPW services more frequently.

--Mowing Operations: When the Park was designed in the Victorian era of the late 19th

century, the Park design emphasized grass lawns coming right to the edge of the water.

Several thousand feet of shoreline in the Park have this look as seen in the photo below.

Unfortunately, while this design and practice presents an aesthetically pleasing appearance,

it is not a wise water quality management

practice: it allows geese to easily go

between the ponds and the shoreline

making the Park an attractive place to

stay; it provides no natural vegetative

buffer to absorb pond nutrients; and it

leads to shoreline erosion in steep slope

areas that are difficult to mow.

Park officials need to commit to letting a large amount of shoreline to go “natural” and not

mow up to the water’s edge.

--Maintenance Operations “Hot Spots”: The HW study identified several areas in non-

public maintenance areas where the operations required better “housekeeping” by Park

staff to minimize pollution from entering the ponds after rain events. Both the area

Grounds Maintenance yard and the Mounted Command facility on Noonan Island need to

develop best management practices to avoid waste from flowing into the ponds.

Geese Management—As pointed out in Section 2, the resident Canada geese have long

contributed to the phosphorous loadings that are harming the Park ponds. In 2012 the first

steps to comprehensively manage the resident geese were undertaken: addling all of the

geese eggs in the Park nests; removing several hundred geese under contract with the US

Department of Agriculture; installing “geese education signs” in key geese feeding areas of

the Park; and public education of park visitors by summer high school interns. The 2012

effort has reduced the resident Canada geese in the Park to approximately 60 geese.

This comprehensive effort needs to continue for several years to keep the resident Canada

geese population in check.

Shoreline Buffer Planting—To

accelerate natural vegetation along the

shorelines, it will be useful to pro-

actively plant native plant species

along many of the Park shorelines. This

will have many water quality

management benefits as discussed

above under “Mowing Operations”.

Steep Slope Stabilization—While most of the sediment that is in the Roger Williams Park

Ponds is the result of sand washed into the ponds from the upper and lower watershed

storm drainage systems, a small amount of pond sediment is from erosion of sloped lawn

areas that have lost their grass cover for one reason or another. These steep slope areas

with bare soil should be systematically re-seeded with appropriate erosion control matting

in September of each year.

Making a Difference: The Public—Clean water in Roger Williams Park is not just a municipal

or public sector responsibility and it will not occur if total responsibility is left with

government actions. Park users, and particularly upper and lower watershed residents,

need to do their part to improve the ponds water quality. The HW study indicates that

upwards of 60-65% of the phosphorous loads coming into the ponds causing the water

quality problems come from outside the Park. Watershed residents and businesses will

need to be continually engaged to learn what they do on their properties affects the storm

water flowing into the Park.

Park officials also need to ramp up

efforts to inform and inspire Park

visitors about restoring the water

quality and biodiversity in the Park

ponds. A significant education and

information program will need to be

developed to develop a constituency

for clean ponds.

4.3 In-Pond Options

While the above land-based options and public outreach will significantly reduce pollution loads

entering the pond, many of the actions will be expensive and will not make a major difference

immediately in the ponds. The in-pond management options discussed below should be considered in

the mix of actions to be implemented.

Chemical Treatment of Aquatic Weeds and Algae—Park officials have been chemically

treating aquatic weeds and algae, under RI DEM permit procedures, for approximately 20

years. Aquatic herbicides are used to treat

rooted aquatic weeds and copper sulfate is

used to treat algal blooms. The doses for

these applications are governed by time of

year and water temperature, are relatively

inexpensive--about $5,000-7,000 per year,

and provide temporary relief for algae and

aquatic plants during the Park’s busy time

of year.

Dredging of Pond Sediment—In the early 1980’s Park officials spent considerable funds

dredging Roosevelt Pond, Willow Pond, and Polo Pond to address the water quality

problems that existed in the ponds at that time. While well-intentioned, it was a very

expensive short-term solution. Because nothing was done to control the sediment and

phosphorous coming in from the upper watershed into Roosevelt Pond, all three ponds have

long since lost the pond depth that was achieved in 1982. In addition, Pleasure Pond has

also lost considerable pond depth.

The lesson from the early 1980’s dredging effort is that water quality improvements have to

be sequenced properly or else the cost benefit of these actions will be significantly reduced.

Dredging will need to be done again at some point in at least 3 or 4 of the Park ponds, but

land based efforts and upper watershed efforts need to be done first.

Chemical Treatment of Exiting Sediment in the Ponds—One of the issues unresolved by the

HW study is the extent to which existing sediment in the ponds releases phosphorous into

the water column under certain depth and dissolved oxygen conditions. This phenomenon

is called “internal recycling” and it may be a significant contributor to phosphorous in the

Park’s deeper ponds, i.e., Cunliff, Elm and Edgewood. When existing phosphorous loads

coming into those ponds from the lower watershed are substantially reduced, water quality

testing will need to determine if internal recycling is an issue. At that point Park officials

may consider treating the sediment with aluminum sulfate or sodium sulfate. This is a

relatively expensive treatment—about $1,500/acre, however, and will require careful

dosing to not harm existing fish in the ponds.

4.4 Mashapaug Pond Flow into the Park: Options

The HW study recognized that the long term goal of reducing phosphorous from the upper watershed

that flows into the Park ponds via Mashapaug Pond will be daunting to achieve. Two cities are involved;

three water bodies; scores of dense residential neighborhoods with no common identity or track record

of working together; one industrial park; and hundreds of stand-alone businesses. While all of the

above discussed structural, non-structural, and public outreach efforts need to be started and pushed

forward, the pace of implementation in the upper watershed will likely be far more challenging than the

efforts in the lower watershed.

In the meantime, phosphorous loadings from Mashapaug Pond—the major source of pollution for Roger

Williams Park—will continue to diminish the other efforts in the lower watershed to reduce storm water

pollution in the Park ponds. What can be done in the interim, before the hundreds of pollution

reduction actions are implemented in the upper watershed? The HW study suggests three important

small scale solutions that will need considerably more study, but which appear to be promising.

Chemical Dosing Station—The 48” pipe that carries the Mashapaug Brook and the storm

water flows from the upper watershed is essentially a point source of pollution for the Park

ponds. The HW study recognized this and suggests chemical treating of the water coming

out of this point source should be considered as an interim measure until solutions in the

upper watershed to reduce pollution are implemented. Their suggestion: a dosing station

that would treat the phosphorous and suspended solids.

One or more aluminum compounds via a drip line feed dosing station, either at the

discharge point in Roosevelt Pond or upstream of the Park, would bind up the phosphorous

and suspended solids precipitating a resultant floc that would fall out of the flow into the

pond. HW recognizes the need for a study to examine the permitting for such a dosing

study, operational requirements, maintenance requirements, treatment protocol, and

disposal of the precipitated floc.

Mashapaug Brook Weir Box Re-engineering—When Route 10 was constructed, some of the

flows from Mashapaug Pond were altered to go through a weir box (just east of RT 10 and

south of the Calart Building) into a 72” pipe that bypasses the Park ponds. Currently all of

the low flows and smaller storm flows are directed towards the Park ponds through the 48”

pipe into Roosevelt Pond. The HW study speculates that if the weir box is modified to divert

more of the storm events into the 72” pipe that bypasses the Park ponds this might reduce

the phosphorous loads that come into Roosevelt pond after storm events. A detailed

engineering study to examine the feasibility of this weir box modification is needed.

Chemical Treatment of Sediment in Mashapaug Pond—RI Department of Environmental

Management indicates in its 2007 report on Mashapaug Pond that “internal recycling” of

phosphorous in Mashapaug Pond maybe a a major contributor to the phosphorous loads

originating from Mashapaug Pond and flowing into the Roger Williams Park ponds during

the summer months. The conditions in Mashapaug Pond in the summer months—relatively

deep pond, high water temperatures, and low dissolved oxygen levels—allow the release of

phosphorous into the water column. Thus, treating portions of Mashapaug Pond during

summer months with some type of aluminum compound may be able to inactivate

phosphorous and bind to the pond sediment impinging the ability of the phosphorus to be

released. A detailed study of this treatment is obviously needed since it may require several

acres of Mashapaug Pond to be treated.

4.0 What Can Be Done: Recommendations

While the Horsley-Witten study outlines an impressive array of best management practices for reducing

storm water pollution in the Park ponds, it is clear that some significant findings should guide Park

officials in deciding how to proceed during the next eight to ten years.

A Long-Term Commitment to Managing the Water Quality in the Park Ponds Is Needed. A

year-by-year set of cost effective solutions for the next several years will be required that

takes advantage of available scarce resources. There are no quick and easy solutions. Park

officials need to plug away each year targeting a sequence of activities to reduce storm water

pollution entering the ponds.

Engineering Solutions Alone Will Not Clean Up the Park Ponds—Public Attitudes Need to be

Changed. The Horsley-Witten looked at 35 structural storm water retro-fit projects to

address the storm water pollution from existing storm water outfalls in the Park(not

including the pipe from Mashapaug Pond) and the total cost was estimated at around $1.8-

2.0 million. The Park can’t simply buy its way out of the pollution problem in the ponds

because these infrastructure projects are expensive and will not address all of the

phosphorous loadings flowing into the ponds. Many of the sources of phosphorous coming

into the Park ponds are the result of human behavior, such as feeding the geese and

residential fertilizer practices in watershed areas near the Park. A consistent public outreach

program is needed to change public behavior and attitudes about the Park ponds.

Water Quality Management Improvements Start at Home. There are a number of

operational and maintenance tasks that Park staff need to focus on to help reduce pond

pollution, including:

o systematic catch basin cleaning

o educating park visitors about geese feeding and littering

o providing shoreline buffer vegetation

o allowing leaves to remain in wooded hillside areas

o diligently addressing slope erosion issues as they develop each year.

We Will Need Additional Study to Determine Long Term Solutions for Some of the Pond

Water Quality Issues. We not only need to provide an annual water quality sampling program

in the ponds to monitor the effectiveness of our on-going efforts, we also need to look at the

following un-resolved and/or on-going storm water issues:

Is it possible to treat the storm water coming into Roosevelt Pond from the Mashapaug

Pond watershed to reduce phosphorous? What are capital and operating costs for such a

system?

To what extent is the existing sediment that is in the Park ponds releasing phosphorous into

the ponds and under what conditions? Is it cost effective to selectively treat the sediment

in some of the ponds? Is it cost effective to treat sediment in Mashapaug Pond?

What would it cost to dredge selective Park ponds and what will be the pollution reduction

from such an effort?

Can storm flows (and the resulting phosphorous loads) from Mashapaug Pond be diverted

away from the 48” pipe entering Roosevelt Pond?

Is it feasible for the City to develop an overall Regional Storm Water Management District

to fund city wide storm water flow and pollution reduction?

The following Roger Williams Park Pond Restoration actions are recommended to be implemented

during the 2013 – 2020 period. Depending on the number of actions implemented and the ability to

reduce phosphorous from the Mashapaug Pond inflow into Roosevelt Pond, these actions will reduce

the phosphorous loadings into the Park ponds by 20 to 50%.

. .

Summary of Watershed Management Plan for Rhode Islands Salt Ponds

. .

90 Route 6A • Sandwich, MA • 02563 Phone - 508-833-6600 • Fax - 508-833-3150 • www.horsleywitten.com

Sustainable Environmental SolutionsHorsley Witten Group

Submitted to:

Rhode Island Department of Environmental Management;the Salt Ponds Technical Advisory Committee;

and the Salt Ponds Coalition

Final Watershed Management PlanExecutive Summary

for Green Hill and EasternNinigret Ponds, South Kingstown and

Charlestown, Rhode Island

April 18, 2007

Final Watershed Management Plan for i Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Executive Summary 4-18-07.doc

i. EXECUTIVE SUMMARY INTRODUCTION This Watershed Management Plan for Green Hill and eastern Ninigret Ponds is an action plan to guide residents, watershed groups, and local, state and federal governments on how to reduce both nutrients and bacteria loadings to Green Hill Pond and eastern Ninigret Pond in order to restore and maintain water quality levels suitable for fishing and swimming. This plan is also intended to provide a model for other salt pond watersheds within the state. The plan includes an introduction section that describes the planning area, a description of the watersheds, partners involved in development of the plan, and a water quality analysis that identifies water quality goals, sources of pollutants, and current loads and/or concentrations. An assessment section documents existing programs and management options for wastewater management, stormwater management, regulatory programs, public education and outreach, and increasing flushing to Green Hill Pond. The management plan presents specific measures for reducing pollutant sources and presents implementation measures that specify what is required, who is responsible, a timeframe for implementation, and how such implementation might be funded. A monitoring plan is provided to measure interim progress of plan implementation and to provide a framework for adjusting management measures in the future. A watershed quality improvement plan was developed by the Rhode Island Department of Environmental Management (DEM) that specifies maximum allowable bacterial levels in the ponds and their tributaries. This is referred to as a total maximum daily load (TMDL) and the bacteria management recommendations are intended to support the TMDL (approved in 2006). Since a nutrient TMDL has not been developed for the ponds, the nitrogen loading calculations and management recommendations presented in this report are intended to be the equivalent of a TMDL. Watershed Description The so-called Charlestown lagoon system is located on the southern coast of Rhode Island and consists of two major basins, Ninigret Pond and Green Hill Pond. Both of these shallow coastal lagoons receive restricted tidal flushing through one narrow man-made breachway between Ninigret Pond and the ocean. Green Hill Pond is located primarily in the southwestern corner of the Town of South Kingstown, Rhode Island with a small portion of the pond extending into southeastern Charlestown, Rhode Island. Green Hill Pond has a surface area of approximately 380 acres and a watershed area of approximately 3,400 acres. Ninigret Pond is located entirely within the Town of Charlestown and is bounded on its northern side by Route 1 and the Charlestown end moraine. It has a surface area of approximately 1,600 acres and a watershed area of approximately 6,000 acres.

Final Watershed Management Plan for ii Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Executive Summary 4-18-07.doc

Over the years, the water quality of Green Hill Pond and eastern Ninigret Pond has diminished. Scientists use a variety of specific measures to gage water quality and/or chemistry including measures such as dissolved oxygen concentration, fecal coliform concentrations, Secchi dish depth, nitrogen concentrations, or Chlorophyll a concentration. Green Hill Pond and eastern Ninigret Pond are listed on the Rhode Island 2006, 303(d) list as being impaired for pathogens and a final TMDL was developed by the Rhode Island Department of Environmental Management (DEM) and approved by the U.S. Environmental Protection Agency (EPA) in February 2006. Green Hill Pond is also listed as impaired for dissolved oxygen (DO), a consequence of excessive nitrogen loading and poor tidal flushing. Bacteria Sources and Concentration Reduction Requirements Green Hill and Ninigret Ponds are designated as Class SA waters. Class SA waters are defined as suitable for shellfish harvesting for direct human consumption, bathing and contact recreational use, and providing habitat for fish and wildlife. Class SA waters must meet a standard for fecal coliform (fc) bacteria of 14 fc/100 ml and no more than 10% of samples can exceed 49 fc/100 ml and a dissolved oxygen standard of not less than 4.8 mg/L at any place or time. Green Hill Pond and eastern Ninigret Pond do not meet the required fecal coliform standard due to elevated levels of fecal coliform bacterial concentrations. In 2002, as part of the TMDL development, DEM used a DNA-based technique to conduct a bacteria source tracking assessment. Sources of fecal coliform bacteria were determined to include humans, wildlife, waterfowl, and domestic pets with the major pathway being the stormwater conveyance system. Septic systems were determined to be the source from humans. Development of the TMDL utilized sampling stations that were located in several locations in Teal Brook, Factory Pond Brook, which are tributaries to Greenhill Pond, Green Hill Pond and eastern Ninigret Pond. The TMDL report cites required reductions in fecal coliform concentrations to comply with water quality standards. Factory Brook and Teal Brook need the greatest reductions in fecal coliform of 95% and 93% respectively based on a mean of all sampling locations. Nitrogen Loading and Water Quality Assessment The other major pollutant source to coastal lagoons such as Green Hill and Ninigret Ponds is nitrogen, which is acknowledged to contribute to impaired water quality by stimulating algae/plant growth in the water column and along the pond’s bottom. Several researchers have developed nitrogen loading estimates to the Salt Ponds over the past several years that evaluate the sources of loads, that documented the elevated loading and concentrations of nitrogen in the ponds, and that report the negative consequences of too much nitrogen loading. In October of 2006, DEM issued a report entitled Determination of Nitrogen Thresholds and Nitrogen Load Reductions for Green Hill and Ninigret Ponds. This report established an appropriate nitrogen loading “target” for each pond to ensure a predictive

Final Watershed Management Plan for iii Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Executive Summary 4-18-07.doc

level of water quality. The management plan partners selected a nitrogen loading and management approach based on a method originally developed by the Buzzards Bay National Estuary Program (BBNEP). The BBNEP method uses sampled water quality data to derive an empirical relationship between watershed mass loading of nitrogen as related to estuary flushing rate and water quality measures of eutrophication. The BBNEP approach characterizes estuarine response as a Eutrophication Index (EI) that is a function of five factors: the mean value of the lowest 20% of dissolved oxygen percent saturation values, mean dissolved inorganic nitrogen (DIN) concentration, mean Secchi depth, mean chlorophyll a concentrations, and mean total organic nitrogen (TON). Eutrophication Indices, calculated using available physical and chemical data collected from the Salt Ponds Coalition Volunteer Water Quality Monitoring Program (Pond Watchers) and DEM were determined to be an average of 45 for Green Hill Pond and an average of 67 for Ninigret Pond. Eutrophication Index Scores of 65 to 100 are considered “good to excellent” water quality, 35 to 65 are considered “fair to good” water quality, and less than (<) 35 are considered typical of eutrophic conditions. Both Green Hill and Ninigret Ponds have been designated by DEM as Special Resource Protection Waters (SRPW) and therefore should have an EI goal of 65 or greater (higher). Applying this approach to Green Hill and Ninigret Ponds, DEM calculated a target nitrogen loading for Special Resource Protection Waters. These targets and existing loads are summarized in Table E1. Table E1. Nitrogen Loading Targets for Green Hill and Ninigret Ponds

Parameter Green Hill Pond Ninigret Pond Pond Area (km2) 1.70 7.38

Average Pond Depth (m) 0.80 1.35

EI Goal1 65 65

Current EI1 45 67

Current Annual Nitrogen Load (lb)1 30,386 79,384 Target Load (lb)1 6,078 84,450

Required Percent Reduction1 80% 0% 1 (DEM, 2006)

The nitrogen loading target identified above was derived using an EI score of 65 which is predictive of “good to excellent” water quality and is the ultimate objective of this management plan. As it will take time and a significant investment to achieve an 80% reduction in nitrogen loading to Green Hill Pond, this plan also recommends a phased or adaptive management approach to watershed planning, where ultimate goals are established based on water quality standards and criteria and interim goals are also defined. An interim goal of reaching an EI score of 50 (associated with the Class SA water use designation) would result in predictive water quality in the “fair to good”

Final Watershed Management Plan for iv Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Executive Summary 4-18-07.doc

condition range and allow for a higher nitrogen loading target of 18,234 lbs/year or require a nitrogen load reduction of 12,152 lbs/year (or approximately 40%) below existing levels for Greenhill Pond. There is currently no nitrogen load reduction needed for Ninigret Pond. However, it is prudent to continue to mange nitrogen loadings to maintain good water quality. ASSESSMENT SUMMARY This section provides a summary of the watershed assessment for the Green Hill and eastern Ninigret Ponds. Given the water quality impairment currently experienced in the ponds, the assessment focused on two contaminants: fecal coliform bacteria and nitrogen. The assessment focuses on current and potential future wastewater management programs, stormwater management programs and options, regulatory programs, public education and outreach methods, other pollutant sources, and the potential for increased flushing of Green Hill Pond. A summary of the analysis for each of two primary contaminants is described below. In addition, a brief summary of recommended additional studies is provided at the end of this section. Nitrogen Nitrogen enters the ponds through groundwater and surface water, with groundwater sources representing approximately 75% of the total load to the ponds. Loadings from individual ISDSs within the watershed are the greatest contributor of nitrogen to the ponds (approximately 74% of the load provided through groundwater and 60% of the total load to Green Hill Pond). As a result, a series of wastewater alternatives were evaluated to develop recommendations to reduce nitrogen inputs. The options considered include:

• Upgrading all ISDSs according to current DEM regulations; • Upgrading all ISDSs with alternative nitrogen reducing systems; • Community or cluster systems for six service areas within the study area; and • The use of nitrogen treatment trenches along the pond shoreline.

The nitrogen reductions provided by these options were then compared to the nitrogen loading target for Green Hill Pond (the pond most severely impacted by nitrogen). None of the wastewater options, on their own, reduce nitrogen loading enough to reach the targeted 80% nitrogen reduction (although the load reduction of the nitrogen treatment trenches was not specifically quantified). The community or cluster treatment alternative comes the closest, providing approximately 16,700 lbs/year of the necessary nitrogen reduction (36% of the total nitrogen load to Green Hill Pond). The community treatment option is similar in cost to the on-site denitrification system option. Both cost in the range of $20,000 to $35,000 per lot. The community system is more attractive because it provides a greater reduction of nitrogen, and eliminates the need for management of hundreds of different on-lot denitrification systems. However, there are still issues with

Final Watershed Management Plan for v Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Executive Summary 4-18-07.doc

this approach. The potential disposal areas identified in this plan still need to be confirmed with field testing, and may, or may not, provide adequate sites for disposal. The community system may foster the development of existing lots of record that are currently unbuildable given existing DEM regulations on ISDSs. There are significant political and institutional hurdles to overcome regarding who would manage the system, who would pay for it, and how it would be financed. An alternative approach of nitrogen removal is also identified in the report. In this approach, a porous reactive “barrier” or treatment trench is constructed in the ground perpendicular to the direction of groundwater flow at a depth sufficient to intercept and interact with the groundwater. The trench is filled with woodchips, which serve as a carbon or food source for denitrifying bacteria. As nitrate-bearing groundwater filters through the trench, the bacteria denitrify the nitrate, causing a decrease in nitrate concentrations. These nitrogen treatment trenches appear to offer a significant benefit to reducing nitrogen loading to the ponds. Further investigations are needed to see if this approach is feasible. There is a need for further data to define the watershed treatment area and the amount of groundwater that flows to the trenches, and there is a need for more research to confirm the long-term treatment efficiency they provide. Engineering and maintenance considerations also need to be fully vetted. However, the trenches have the potential to provide the greatest nitrogen reduction at the least cost. In addition, the approach is attractive because it treats all sources of nitrogen in groundwater that pass through the barrier and because it can have an immediate impact on the quality of groundwater entering the pond (as opposed to other options that will only affect water quality over the long term). The towns of South Kingstown and Charlestown are in the process of further assessing the most appropriate wastewater treatment options in a pending wastewater treatment facilities plan. This plan is scheduled to be completed by December 2007. Although stormwater is a major contributor of bacteria and other pathogens, nitrogen loading from stormwater is not as significant as the loading from other sources in the watershed, particularly wastewater sources. The results of the MANAGE model show that surface runoff load is not reduced significantly by the handful of structural end-of-pipe practices. However, the implementation of small-scale practices across the watershed can make a significant reduction in nitrogen loading. Although there are few “centralized treatment options” for stormwater in this watershed, the small-scale solutions, in conjunction with end-of-pipe solutions, will help reduce nitrogen loads incrementally over time. Another option to reduce the impacts of nitrogen loading is to increase the flushing within Green Hill Pond. This could be done through the construction of a new opening from Green Hill Pond across the barrier beach into the ocean. This direct opening would allow a greater exchange of water than is currently provided through the single opening in Ninigret Pond. The opening could be permanent, or periodic (seasonal). The creation of a permanent opening would require significant armoring, at tremendous expense, to prevent the new entrance from closing, shifting or filling in with sediments from coastal erosion. The creation of a new opening would require a complex environmental analysis

Final Watershed Management Plan for vi Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Executive Summary 4-18-07.doc

and permitting process through the CRMC and the Army Corps of Engineers. The analysis would have to consider the benefits of the increased flushing versus potential changes in habitat in the pond due to changes in water level, salinity, and other potential factors. A breachway would also require an suitable parcel of land. The parcel with the best potential is owned by DEM, however it appears that the deed would preclude constructing a breachway. Fecal Coliform Results from the Green Hill Pond bacteria source tracking project conducted by DEM in the fall of 2002, suggest that waterfowl and wildlife are a major source of fecal coliform to the pond. Stormwater runoff can act as the delivery mechanism for much of this animal-derived bacteria. The study also found evidence of human sources of fecal coliform but not at as high a frequency as other animal sources. The study was conducted during a drier than normal period. Failing septic systems may play a more significant role in pollutant loadings to the ponds in wetter years and when groundwater is elevated. All of the wastewater management options will also help to reduce bacterial concentration to the ponds, with the exception of the nitrogen treatment trenches. Currently, properly functioning ISDSs are already reducing bacterial concentration. Given the current relatively low hydraulic failure rate of ISDSs in both Charlestown and South Kingstown, it is unlikely that wastewater is the primary source of bacterial concentration to the ponds. Future ISDSs failures, outbreak and overflow events, pipe breaks, as well as overflows associated with the community sewerage options may continue to contribute a modest level of bacterial concentration, but this contribution is probably negligible when compared to the contribution from stormwater runoff. Bacteria can be removed to a certain extent through structural stormwater practices such as infiltration, constructed wetlands, water quality swales, and bioretention, with infiltration being the most effective structural control. However, since infiltration is not feasible in areas adjacent to the end-of-pipe outfalls to Green Hill and Ninigret Ponds, the most effective method to reduce fecal coliform levels is by implementing a combination of structural controls combined with source controls. Non-structural stormwater source controls and habitat modifications, including wildlife management, are therefore important measures and receive significant attention in the watershed management plan. Recommendations for Additional Studies While numerous studies have been performed for the Rhode Island South Shore Salt Ponds, the watershed assessment revealed the need for other studies that would aid in the decision making process for implementation of watershed plan recommendations. A preliminary list of additional recommended studies includes, but is not limited to:

• Further analysis of groundwater flow and capture amount to the nitrogen treatment trenches;

Final Watershed Management Plan for vii Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Executive Summary 4-18-07.doc

• Developing a wastewater management facilities plan (which is Pending); • Conducting a review of waterfowl/wildlife management strategies that focuses on

nuisance waterfowl and wildlife (e.g. raccoons, skunks, and foxes) and better control measures; and

• A study that evaluates the effectiveness of existing regulations, such as determining how many existing sites comply with current CRMC buffer regulations.

Regulatory programs and public education and outreach currently provide a range of measures to minimize nitrogen loading and fecal coliform concentrations to the ponds. These include regulations at the federal and state level, including the total maximum daily load (TMDL) program, the Rhode Island Pollution Discharge Elimination System (RIPDES) Phase II Stormwater program, Coastal Resources Management Council (CRMC) regulations for activities on or within 200 feet of a shoreline feature, the CRMC Special Area Management Plan (SAMP) for the Salt Ponds Region, and Rhode Island Division of Fish and Wildlife nuisance species control programs. Local regulations include controls in the local zoning ordinances in both South Kingstown and Charlestown. Both towns have adopted local Watershed Management Districts that provide for mandatory inspection and maintenance programs of ISDSs, and both towns are subject to RIPDES Phase II requirements to implement stormwater controls to reduce nitrogen loading. Public education and outreach programs are generally voluntary at the town level (with the exception of Phase II stormwater program requirements). The Salt Ponds Coalition provides significant educational and outreach programming. Key educational areas include:

• Waterfowl and wildlife management; • Lawn care management; • Pet waste management; • Stormwater management; and • Septic system maintenance.

MANAGEMENT AND IMPLEMENTATION RECOMMENDATIONS The watershed plan presents a phased or adaptive management approach to improve water quality in the ponds. The first step is to increase water quality to a “good” level by implementing near-term actions. The next step is to implement a second level of actions, such that “excellent” pond conditions that can be achieved by actions considered more long-term. The watershed management plan presents a suite of available options pertaining to wastewater management, stormwater management, regulatory mechanisms, public education and outreach, and other management of pollutant sources. All of these options are presented in a Watershed Management Toolbox in Appendix L of this plan, with the preferred recommendations presented as an implementation plan. This plan also presents a Watershed Monitoring Plan that outlines existing monitoring programs and

Final Watershed Management Plan for viii Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Executive Summary 4-18-07.doc

recommended monitoring indicators. The watershed management implementation measures are summarized in Table E2. Detailed descriptions of the proposed management and implementation measures are provided in Section 3 of the watershed plan.

Final Watershed Management Plan for ix Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Executive Summary 4-18-07.doc

Table E2. Watershed Management Implementation Plan Summary Term Target

Pollutant Action Item Responsible Party

Near Long Nitrogen Bacteria Wastewater Management Wastewater Facilities Plan

Town Councils of South Kingstown and Charlestown

X X X

Stormwater Management Site 3: Elm Road Retrofit South Kingstown Town Council X X

Site 6: Dawley Road Retrofit

South Kingstown Town Council X X

Site 2: Shore Road Retrofit Charlestown Town Council X X Site 1: Arches Road Retrofit Charlestown Town Council X X Sites 7&8: Matunuck School House Road and GH Beach Rd.

South Kingstown Town Council X X

On-lot, Community and Roadway Stormwater Treatments

Individual homeowners, Neighborhood or Condominium Associations, Town Councils

X X X

Regulatory Programs Overlay Districts Planning Commission/Town

Councils of each town X X X

Subdivision and Land Development Ordinance/Regulations

Planning Commission/Town Councils of each town

X X X

Phase II Stormwater Management Ordinance

Planning Commission/Town Councils of each town

X X X

Stormwater Management Program Plan (in accordance with Phase II)

South Kingstown – Dept of Public Services, Charlestown – Dept. of Public Works

X X X

Performance Based Wastewater Treatment Standards

South Kingstown – Conservation Commission, Charlestown Wastewater Management Commission

X X X

Public Education and Outreach Education of Local Officials Salt Ponds Coalition, DEM,

CRMC X X X

Annual Watershed Awareness Day

Salt Ponds Coalition X X X

Adopt-a-Pond Organization Salt Ponds Coalition X X X Demonstration Projects Town Public Service/Public

Works X X X

School Watershed Science Programs

Town School Committees, Teachers

X X X

Other Pollutant Sources Wildlife Management Study DEM. X X X

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In Poor water quality, or Eutrophic areas, nutrients entering each bay from its surrounding watershed far exceed the water body’s capacity to absorb them, degrades habitat and greatly inhibits the ability of the bay to function as a viable ecosystem. Dissolved oxygen levels in the water become low and reach conditions which are detrimental to marine life. Biodiversity within the system is severely limited with all but the most resilient species remaining. The water is murky with visibility of less than 2 feet. Eelgrass beds are absent and the bottom may be smothered by dense algae. At the extreme, the water may smell like rotten eggs and the bottom sediments may have a mucky consistency (like black mayonnaise) and be largely devoid of life.

Harbors and Coves characterized as Fair are transitional areas either improving or more likely declining due to increasing nutrient loading from their watersheds. The habitat health is impaired. Low oxygen levels are algal blooms occur periodically. Reductions in water clarity and sunlight penetration due to algal and phytoplankton growth have resulted in loss of eelgrass beds, particularly in the inner portions of the bay. Marine biodiversity – including fi sh and shellfi sh – have declined and mats of algae may cover segments of the bay bottom.

In areas with Good to Excellent water quality, nutrient inputs are in balance with the bay’s natural ability to utilize them. These regions provide high quality habitat for fi sh and shellfi sh. Water clarity is excellent with sunlight penetration and visibility greater than 6 feet. Sustained and high levels of dissolved oxygen and infrequent algal blooms support conditions favorable to eelgrass beds and allow for the full range of marine biodiversity within the system including sensitive species such as the Bay Scallop.

Figure 7. Graphic depiction of how water quality relates to Eutrophication Index (EI).

Poor Water Quality Fair to Good Water Quality Good to Excellent Water Quality

EI = 0 EI = 100

Eutrophic Conditions

Source: adapted from Coalition for Buzzards Bay, 2001

EI = 35 EI = 50 EI = 65

Class SA Waters ONRW Waters

Final Watershed Management Plan for 19 Horsley Witten Group, Inc. Green Hill and Eastern Ninigret Ponds April 18, 2007 South Kingstown and Charlestown, RI J:\4095 R.I. South Shore Salt Ponds\Reports\Final Management Plan\Final Watershed_Mgmt_Plan.doc

Figure 8: Land Use Derived Sources of Nitrogen Loading to Green Hill Pond from Groundwater (source: URI MANAGE Model, 2005)

Figure 9: Land Use Derived Sources of Nitrogen Loading to Ninigret Pond from

Groundwater (source: URI MANAGE Model, 2005)

These figures indicate that septic systems are the most significant contributor to nitrogen loading to groundwater and that groundwater flow is the dominant contributor to total flow into the ponds.

Agriculture 8.6%

Open Space 3.7%

Lawns 8.7%

Pets 4.7%Septic 74.3%

Lawns 13.5%

Pets 3.5%

Agriculture15.6%

Septic 58.2%

Open Space 9.1%

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Summary of Pleasant Bay Fertilizer Management Plan Final Report

. .

Pleasant Bay Fertilizer Management Plan i Horsley Witten Group, Inc. Final Report December 2010

EXECUTIVE SUMMARY

Like many Cape Cod estuaries, Pleasant Bay (the Bay) is threatened by excessive loading of nitrogen from development within its watershed. While wastewater from on-site septic systems is the primary source of nitrogen loading, the focus of this project is on controlling fertilizer loadings to the Bay, which are an important secondary source of nitrogen within the watershed. Based on a review of the current fertilizer loading information, and an analysis of options to control future loading, an action plan has been developed that has the potential to reduce the overall controllable nitrogen load to the Bay by 5.2%. This project, funded through a grant to the Pleasant Bay Alliance from the Cape Cod Water Protection Collaborative, has been designed to investigate the following fertilization issues:

What is the current contribution of nitrogen from fertilizers in the Pleasant Bay watershed and how significant is it in comparison to that provided by wastewater discharges?

What current regulations exist in the four Pleasant Bay watershed towns (Brewster, Chatham, Harwich, and Orleans) that support the management of fertilizer use?

Are there examples from other communities around the country that could be considered for use in the Pleasant Bay watershed?

What specific recommendations should be considered for Pleasant Bay, what issues exist with their implementation, and what credit towards the nitrogen total maximum daily loads (TMDLs) can be achieved for each?

The Horsley Witten Group, Inc. (HW) and Effective Organics began this project with an in-depth review of the current and future nitrogen loadings to Pleasant Bay based on land use analyses conducted by the Massachusetts Estuaries Project (MEP) as part of their development of nitrogen loading limits or Total Maximum Daily Loads (TMDLs) for the Pleasant Bay sub-watershed. TMDLs are critical contaminant or pollutant thresholds that are protective of the habitat within the Bay. The nitrogen TMDLs are currently being used as the target that must be met by towns within the watershed as part of their watershed planning efforts. A significant reduction below current nitrogen loading rates is often needed to meet these TMDLs. Using the MEP model for Pleasant Bay, HW quantified the current contribution of nitrogen from fertilizers in the Pleasant Bay watershed and how this compares to wastewater contributions. HW reviewed fertilizer assumptions from the model, and resulting nitrogen loading estimates for each of the 95 sub-watersheds to the Bay, as delineated by the MEP model (Figure ES-1). Fertilizer applications comprise 15.4% of watershed-based, or controllable nitrogen loading to Pleasant Bay. Golf course fertilizers represent the largest controllable source of nitrogen fertilizer input to the Pleasant Bay watershed at 8.3%, with residential lawn fertilizers representing 6.8% of the watershed load. The MEP model estimates that nitrogen loading from residential lawn fertilizer could potentially increase by 40% under residential build-out conditions.

Pleasant Bay Fertilizer Management Plan ii Horsley Witten Group, Inc. Final Report December 2010

HW compiled existing municipal and regional regulations and policies for fertilizer management from the Pleasant Bay Towns of Brewster, Chatham, Harwich, and Orleans, as well as the latest Cape Cod Commission Regional Policy Plan, and identified performance standards related to fertilizer management. Most of the existing town regulations were developed with the goal of protecting drinking water supplies and other water resources, and are therefore designed to manage nitrogen loading within the wellhead protection areas to the towns‟ wells (Zone I and Zone II), and within buffers to resource areas. Existing town regulations do not specifically control loading impacts to Pleasant Bay or other coastal estuaries; however towns offer some protection through buffers to wetland resource areas, which could include Pleasant Bay or one of its sub-watersheds. In addition, the town Conservation Commissions take the opportunity to control lawn size and lawn fertilization practices in the issuance of Orders of Conditions for new projects within their jurisdiction. All four towns within the Bay currently require a 50-foot “no disturb” buffer around wetland resource areas. HW recommends that town Conservation Commissions continue to strictly enforce those provisions and also work with property owners seeking Orders of Conditions on existing developed properties to enhance or restore buffers. HW conducted a review of fertilizer management strategies used by other municipalities across the country to gain insight into practices used elsewhere that may be applicable for use in the Pleasant Bay Watershed. Based on this search, HW identified and evaluated 16 programs for their applicability within the Pleasant Bay watershed towns, including regulatory programs such as model ordinances and bylaws, non-regulatory programs such as education and outreach, and Best Management Practices (BMPs) for fertilizer applications such as organic lawn care, nutrient management, and golf course management. Based on analyses of the MEP model, existing regulations of Pleasant Bay towns, and fertilizer management practices across the country, HW initially identified 17 strategies that were presented for consideration by the Pleasant Bay Alliance Watershed Work Group. These strategies were then the focus of a detailed discussion at a May 26, 2010 Work Group meeting to select the following six strategies for further analysis:

1. Management strategies to minimize fertilizer applications on municipal properties, athletic fields and parks;

2. Strategies to minimize, to the extent feasible, fertilizer applications on golf courses, as they represent 8.3% of the total controllable nitrogen load to Pleasant Bay;

3. Enforcement of 50-foot no disturb buffers around wetland resource areas, and restoration or enhancement of wetland buffers on existing properties where possible;

4. Outreach and education techniques for year-round residents, second home owners, and landscape professionals to encourage improved fertilizer practices;

5. Training for turf grass managers to encourage fertilizer and landscaping practices to minimize the use of nitrogen; and

6. Regulations to reduce the size of lawns created through future development within the watershed, as fertilizer applications from existing residential development constitutes 6.8% of the controllable load to the Bay.

A summary of the benefits of these recommendations, implementation issues and costs are provided in Table ES-1, and they are discussed in more detail in Section 5 of the report.

Pleasant Bay Fertilizer Management Plan iii Horsley Witten Group, Inc. Final Report December 2010

Table ES-1. Summary of Fertilizer Management Recommendations

Strategy

Potential Reduction in N Fertilizer Load

Leached Implementation Long Term

Needs Comments

Lbs/ Year

% of Current Controllable

Load Needs Initial

Timing

1. Municipal fertilizer best management practices

200 0.2%

General bylaw or municipal policy

3-6 months

Annual training of municipal staff

This would show the Town plays a leadership role in nutrient management

2. Golf course fertilizer management with targeted nitrogen reduction

3,650 3.5%

Agreement, General bylaw or municipal policy

3-6 months

Town staff time to review golf course fertilizer application data

This would be developed and adapted in consultation with golf course managers and municipal officials

3. Continued enforcement of “No-disturb” buffers

n/a n/a

Ongoing enforcement of required buffers

3-6 months

Conservation Commission staff time to review applications

This provides an opportunity to improve buffers on existing, developed lots.

4. Public education and outreach

1,560 1.5% Education and outreach

12 months to start; ongoing after that

Ongoing investment in outreach

This would help build support and consensus for policies, bylaws, and zoning amendment

5. Turfgrass Management Training

n/a n/a

Develop-ment of training course

3-6 months

Ongoing investment in training professionals

This would help build support and buy-in among professionals

Total

(Existing N

Load)

5,410 5.2%

6. Lawn size limit for new development (future load)

1,333 1.3%1 Zoning amendment

3-6 months

Planning Board staff time to review applications for new development

Reductions can be easily calculated, but only apply to new development

1 This percentage was calculated based on current loads, because future loads are unknown for

the watershed. This strategy addresses future development.

Pleasant Bay Fertilizer Management Plan iv Horsley Witten Group, Inc. Final Report December 2010

During the development of these strategies, HW met with Brian Dudley of the Massachusetts Department of Environmental Protection (DEP) to discuss DEP‟s opinion on how specific approaches to fertilizer management could help reduce nitrogen loading to reach the TMDLs for the embayment system. According to DEP‟s initial guidance, the strategies must show a direct, verifiable reduction in nitrogen loading for credit to be given towards a particular TMDL. Examples that could be verified include the reduction in lawn area on a property, a restriction in new lawn sizes, or quantifiable changes in fertilizer practices at municipal fields or golf courses. DEP also remains open to discussing how fertilizer reductions achieved through education and outreach could be achieved and quantified. The concept of a pilot outreach program was discussed to evaluate the extent of change in homeowner practices over time. The strategies discussed below take these issues into consideration. Adoption of the five strategies targeting current nitrogen loading (i.e., the first five listed above and in Table ES-1 could result in an overall nitrogen loading reduction of approximately 5,400 pounds (lbs)/year, which represents 5.2 % of the controllable nitrogen load within the watershed (Table ES-1). In addition, the sixth and last strategy targeting residential lawns for future development could result in reduced nitrogen loads associated with future development. While these actions, on their own, do not solve the water quality problems experienced in Pleasant Bay, they can play an important role in the overall water quality management of the Bay, driven by the wastewater planning efforts in each watershed town.