the state of webber pond

The State of Webber PondUnderstanding the Factors

Affecting Water Quality in the Webber Pond Watershed

Colby Environmental Assessment TeamColby College Biology Dept.

December 5, 2002Vassalboro Town Office

PART 1

Presentation OverviewIntroduction

Water Quality Analysis

Land Use Analysis

- Intermission -

GIS Analysis and Models

Future Predictions

Remediation Measures

Recommendations

An Introduction to the Study of Webber Pond

Erin Estey

Study Objectives

Measure Water Quality of Webber Pond:

Physical parameters• DO, Temperature, Turbidity, Conductivity

Chemical parameters• Total phosphorus, Nitrates, Hardness, pH, Alkalinity

Compare to historical data• DEP water sampling since 1972

Members of CEAT performing water quality tests.

Study Objectives

• Calculate proportion of Webber Pond watershed covered by various land uses:

-Road surveys-Residence counts-Buffer strip surveys-GIS land use map analysis-1997 aerial map-1956 aerial map

Residential development in the watershed

Study Objectives

• Project the future condition of the Webber Pond watershed:

- Create Models

- Calculate Phosphorus Loading Model - Calculate population trends

- Project future development

- Recommend best remediation

techniques

Septic suitability model

Characteristics of Maine Lakes

• Important resources in Maine: Recreational, Economic values

• Due to glaciations, many Maine lakes are oriented in a northeast

to southwest direction

QuickTime™ and aPhoto - JPEG decompressor

are needed to see this picture.

A Webber Pond Sunset

Lake Strata

Lake Turnover

• Webber Pond is dimictic– Summer thermocline– Fall turnover– Winter stratification– Spring turnover

• Turnover re-oxygenates the lake, recycles nutrients

Trophic Status of LakesCharacter Oligotrophic Eutrophic DystrophicBasin Shape narrow and deep broad and shallow small and shallowLake Shoreline stony weedy stony or peatyWater Transparency high low lowWater Color green or blue green or yellow brownDissolved Solids Low, deficient in

NHigh, especially in N and Ca

low, deficient in Ca

Suspended Solids low high lowOxygen high high at surface,

deficient under ice, in thermocline

High

Phytoplankton many species, low numbers

few species, high numbers

few species, low numbers

Macrophytes few species, rarely abundant, but found in deep water

many species, abundant in shallow water

few species, some abundant in shallow water

Fish few species (salmon and trout)

many species, especially minnows

extremely few species, often none

Nutrients

• Webber Pond is eutrophic, which means that it is high in nutrients.

• High nutrient levels (especially nitrogen and phosphorus) lead to large phytoplankton communities.

• Increased productivity leads to increased sedimentation and aging of the lake.

The process of sedimentation over time.

Defining a Watershed

• Total area contributing flow to a particular basin.

• Defined as the highest points of land that surround it.

Historical Perspective of the Webber Pond Watershed

• 1950’s - 1960’s large chicken farms.

• Now small vegetable farms, orchard, golf course, lakeshore residences.

• 1972 Maine DEP began secchi disk sampling.

• Current algal blooms are not as severe as those in 1960’s - 1970’s.

• Reconstructed in 1986, it’s used to regulate water levels.

• Benefits of stabilizing water levels:

– Minimize shoreline erosion

– Provide stable environment for flora/fauna

– Allows for flushing of high-nutrient water

• 33 percent of the lake volume can be drawndown with dam

The Webber Pond Dam

The Webber Pond Dam

Geographical Perspective of the Webber Pond Watershed

• Part of the Lower Kennebec River watershed

• A heavily populated area

• Webber Pond covers 1,238 acres

• The Webber Pond watershed covers

5,292 acres

• Webber Pond receives water from

Threemile Pond, Threecornered Pond, Mud Pond

Lower Kennebec River watershed

Biological Perspective of the Webber Pond Watershed

• Submerged aquatic plants around periphery

• Nine species of native fish:

American Eel, Fallfish, White Sucker, Brown Bullhead, Chain Pickerel, Banded Killfish, Red Breasted Sunfish, Pumpkinseed, Yellow Perch

• Largemouth Bass, Smallmouth Bass, White Perch were introduced but not actively stocked

Smallmouth bass (Micropterus dolomieu)

Fish Stocking of Webber Pond

• Brown Trout and Brook Trout have to be replaced due Webber Pond water quality.

• Alewives are anadromous, movement blocked by dams

• In the short-term, Alewives may deteriorate water quality

• In long-term, Alewives may help water quality

Brook Trout Salvelinus fontinalis Sea-run Alewife Alosa pseudoharengus

Introduced Plants

• 11 species pose a threat to Maine lakes• Problematic because:

– spread by fragments – grow rapidly – outcompete natives– hard to eradicate, control

• Webber Pond is at a high risk because: – soft, shallow bottom– public access via boat ramp

Eurasian Watermilfoil (Myriophyllum spicatum)

Water Chemistry

Serena Vayda

Sample Site Locations

3 characterization sites7 spot sites4 tributary sites

Water Quality Assessment Methodology

Insert picture of boat

Sampling Dates:28-Jun-0212-Jul-02

05-Aug-0212-Sep-0223-Sep-02

Water Quality Parameters

Physical Measurements:•Dissolved Oxygen (DO)•Temperature•Transparency•Turbidity•Color•Conductivity

Chemical Measurements:•pH•Hardness•Alkalinity•Total Phosphorus•Nitrates

Dissolved Oxygen (DO)QuickTime™ and aGraphics decompressorare needed to see this picture.

131211109876543210

0 1 2 3 4 5 6 7 8 9 10Dissolved Oxygen (ppm)

28-Jun-2002

12-Jul-2002

5-Aug-2002

12-Sep-2002DO: Measurement of concentration of O2 in water column

Stratification leading to anoxia

Phosphorus implications

Impact on fisheries

Transparency

•Transparency less than 4 m indicates eutrophic conditions

•September mean is 1.24 m•2001 mean is 2.8 m=Eutrophic

•Measures water clarity as an indicator of trophic state

Selected Test Results:(physical characteristics)

Turbidity:

Optical property-measuresscattering and absorption oflight in water column

Webber Pond mean = 5.89 NTU

Natural waters <50 NTU

Color:

Contributes to depth that light can penetrate water

Mean = 18.5 SPU

Comparable to other lakes in region

Conductivity: ability of water to conduct electrical current

Mean = 39.3 µMHOs/cmMaine avg is 20 to 40 µMHOs/cm

Physical Characteristic: Chemical Characteristic:

Alkalinity: Capacity to neutralize acidHigh alkalinity can buffer against pH changesMean = 37 ppm-good buffer

Selected Test Results:(chemical tests)

pH:Measure of acid balanceof a solutionMaine lakes range betweenpH 6.1 and pH 6.8Healthy lakes range between pH 6-8.5

Webber Pond mean = 7.4

Hardness:Measure of total concentrationof calcium and magnesium ions

Mean = 2.91 ppmSoft lake

Good for fish, vulnerable to algae blooms and phosphorus loading

Nutrient Levels

Paul Mathewson

Nutrient Loading

• Plants need a variety of essential nutrients for growth

• Phosphorus and nitrogen limiting in aquatic ecosystems

• Cultural Eutrophication

Phosphorus

• Found in all soil types

• Common in fertilizers

• Septic systems / Animal waste

• Critical Limit = 12 ppb to 15 ppb

Algal Bloom on a Florida Lake

Historical Phosphorus

Mean Concentration = 28.2 ppb

Summer Phosphorus Data

Mean Surface Concentration = 19.4 ppbMean Mid-depth Concentration = 19.9 ppbMean Bottom Concentration = 79.4 ppb

Mean Epicore Concentration = 21.0 ppb

Fall Phosphorus Data

Mean Surface Concentration = 35.7 ppbMean Mid-depth Concentration = 34.6 ppbMean Bottom Concentration = 191.0 ppb

Mean Epicore Concentration = 36.7 ppb

Spot Site PhosphorusAverage Concentration = 30.6 ppb

Sediment Release

•Phosphorus accumulation in hypolimnion

•Oxygenated water: ferric phosphate

•Anoxic conditions: phosphorus release

Epicore and Bottom Phosphorus Concentrations in 2002

Historical Epicore and Bottom Phosphorus Concentrations

Mean Epicore Concentration = 29.5 ppb

Mean Bottom Concentration = 249.8 ppb

Nitrates

• Common ingredient in commerical fertilizers

• Septic leaks / Animal waste

• Fixation by cyanobacteria

Healthy levels under 1 ppm

Mean concentration in Webber Pond = 0.07 ppm

Tributaries

• Knowledge of tributary water quality is essential to understanding the water quality of a lake

• Most tributaries seasonal and/or ephemeral

• Only four carrying water during fall testing

Seaward Mills Brook

Tributary PhosphorusMean Concentration = 81.5 ppb

Watershed Land Use PatternsChris Makarewich

Land Use Assessment• Land use types have varying effects on lake water quality

• Different surface covers influence surface runoff and erosion

• Assessment of land use patterns and historical trends essential to evaluate ecosystem health

Steps in Creating the Land Use Map

1. Obtain Digital Orthophoto Quads

2. Import into ArcView 3.2 (GIS computer program)

3. Determine land use categories

4. Digitize land use areas through polygons

5. Derive and summarize areas

What is a GIS?GIS = Geographic Information System

www.esri.com

• Uses a common coordinate system

• Combine geographic data with theme values and attributes

• Creates layers of information for each theme

GIS Inputs

1997 Digitized Aerial Photograph

Classification of land use types

(Agriculture)

Completed 1997 Land Use Map

Final Product

Land Use CategoriesNatural Uses

• Wetland

• Mature forest

• Transitional forest

• Reverting land

Developmental Uses

• Agriculture

• Cleared

• Commercial / Municipal

• Golf Course

• Open Residential Land

Wetlands• Transition from aquatic to

terrestrial ecosystems

• Natural buffer against nutrients and sediments

• In 1997 covered 0.5% of watershed area

• Closed, continuous canopy

• Best buffer from runoff and erosion

• In 1997 covered 15.7% of watershed area

Mature Forest

• At least 50% canopy cover

• Provide some erosion prevention as well as water and nutrient absorption

• In 1997 covered 49.7% of watershed

Transitional Forests

• Land succeeding from agriculture towards forest

• Results in a canopy cover of less than 50%

• In 1997 covered 7.7% of watershed

Reverting Land

• Land cleared for timber harvest

• Increases surface runoff and erosion

• In 1997 covered less than 1% of watershed

• No major logging companies

• Clearing of land carried out under zoning regulations

Cleared Land

Agriculture

Cropland

• Crop rows indicate planting

• Addition of pesticides and fertilizers

• In 1997, covered 9.1% of watershed

• Agricultural land with no planting rows

• Compaction leads to increased runoff

• Presence of animal waste

• Covered 4.7% of watershed

Pasture

Nutrient Management Plans

• Qualifications for a nutrient management plan

- more than 50 animal units

-request federal funding

-complaint registered

• Plans developed by a certifier trained by MDA

• Not examined unless a complaint is registered

• Currently 150 acres under nutrient management plans in the watershed

Control amount of nutrients added to a field

Maine Department of Agriculture

(MDA)

Commercial and Municipal Land

Golf Course

• All businesses and public facilities

• Impervious surfaces increase runoff

• Less than 1% of watershed area in 1997

• Addition of fertilizers and pesticides

• In 1997, covered 3.4% of watershed

• Proximity to Webber Pond

Open Residential Land

• Land developed for the creation of homes

• Increased runoff adds to erosion

• Presence of septic systems

• In 1997, covered 7.1% of watershed

17.7

349.6

2

35.9

0.815.7

49.7

7.7

13.8

3.47.1 2.8

Webber Pond 1956 Webber Pond 1997

Mature Forest

Transitional Forest

Reverting Forest

Cleared

Agriculture

Golf Course

Open Residential Land

Other

Historic Trends in Land Use

Summary of Land Use Changes

• Decreased agriculture

• Increased total forest area

• Increase in open residential land

• Careful to maintain mature forest tracts and wetlands in future

Land Use Analysis

Madeleine Mineau

Shoreland Zoning

• Minimum residential lot size: 40,000 sq.ft

• Minimum residential shore frontage: 200 ft

• Maximum height of structures: 35 ft

• All structures are required to be set back a minimum of 100 horizontal feet from the normal high water mark.

Shoreland Zoning (continued)

• Campground: Camping areas shall contain a minimum of 5000 sq. ft of land for each site.

• Clearing of vegetation is prohibited within 75 feet horizontal distance of the shoreline.

• There shall be no cleared opening greater than 250 feet in

the forest canopy.

Discussion

• Many non-compliant homes observed. Probably pre-date shoreland zoning ordinance.

• The Vassalboro Code Enforcement Officer expressed a concern about the lack of restrictions regarding converting seasonal residences into permanent residences.

Buffer Strips• Absorb runoff to control nutrients entering the lake.

• A good buffer consists of several vegetation layers and a variety of plants and trees to maximize benefits.

• Natural vegetation form the best buffers.

• Riprap can also be used to protect shoreline erosion.

Buffer Strip Scoring

Score determined according to lakeshore coverage, buffer depth and composition, slope, lot distance and need for riprap. Score range 1 – 20.

1 - 9 Poor10 – 15 Partial16 – 20 Adequate

Poor Buffer

Good Buffer

Buffer Strip Quality Map of Webber Pond

% for each categories

•Adequate: 28.1%•Partial: 50.3%•Poor: 21.6%

House Count

• Assess intensity of residential development in shoreline area and in the watershed as a whole.

• Identify and locate other land uses such as: farms, schools commercial buildings.

• Assess impact on nutrient

loading of the lake.

Shoreline Non-Shoreline

Total

Seasonal 93 17 110

Year-Round

29 179 208

Unknown 31 0 31

House Count Data

•Total number of houses counted: 349

•Other Buildings and landuse noted:

- School- Farms- Golf Course- Boat Storage- Tree Farms- Orchard- Nursery

Subsurface Disposal Systems

• Must conform with State of Maine

Wastewater Disposal Rules

• Minimum setback of 100 horizontal

feet from the normal high water mark.

Town of Vassalboro Ordinances

Town of Vassalboro Ordinances (continued)

By December 31, 1995 all wastewater disposal systems in the Shoreland Zone must have:

• Provided documentation showing the existing system was installed after July 1, 1974Or

• Installed a new system in compliance with State of Maine regulations

Webber Pond Watershed Subsurface Disposal Systems

• Almost all systems are septic systems, no holding tanks, one outhouse and one chem-toilet.

• State funding is used to help residents with cost of upgrading their system.

• Green Valley Campground uses several leach fields up hill from camp sites.

Roads Results and Discussion

•Roads create cleared areas that increase erosion and sedimentation while creating channels that direct nutrient rich runoff towards the lake.

•Poorly maintained camp roads present the largest environmental problem facing Maine watershed health.

•Road areas: 14.15 acres of unpaved road, 27.5 paved

•Road ratings: 14 good, 13 acceptable, 10 fair, 6 poor and 1 very poor.

Road Survey

Map

Intermission