The State of Webber Pond Understanding the Factors Affecting Water Quality in the Webber Pond Watershed PART 1 Colby Environmental Assessment Team Colby College Biology Dept. December.
Download ReportTranscript The State of Webber Pond Understanding the Factors Affecting Water Quality in the Webber Pond Watershed PART 1 Colby Environmental Assessment Team Colby College Biology Dept. December.
The State of Webber Pond Understanding the Factors Affecting Water Quality in the Webber Pond Watershed PART 1 Colby Environmental Assessment Team Colby College Biology Dept. December 5, 2002 Vassalboro Town Office Presentation Overview Introduction 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 Quic kTime™ and a Phot o - JPEG dec ompres s or are needed to s ee t his pic ture. 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 Lakes Character Basin Shape Lake Shoreline Water Transparency Water Color Dissolved Solids Oligotrophic narrow and deep stony high green or blue Low, deficient in N Eutrophic broad and shallow weedy low green or yellow High, especially in N and Ca Dystrophic small and shallow stony or peaty low brown low, deficient in Ca Suspended Solids Oxygen low high high high at surface, deficient under ice, in thermocline low High Phytoplankton many species, low numbers few species, rarely abundant, but found in deep water few species (salmon and trout) few species, high numbers many species, abundant in shallow water few species, low numbers few species, some abundant in shallow water many species, especially minnows extremely few species, often none Macrophytes Fish 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. The Webber Pond Dam • 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 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 Lower Kennebec River watershed • Webber Pond receives water from Threemile Pond, Threecornered Pond, Mud Pond 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 sites 7 spot sites 4 tributary sites Water Quality Assessment Methodology Sampling Dates: 28-Jun-02 12-Jul-02 05-Aug-02 12-Sep-02 23-Sep-02 Insert picture of boat Water Quality Parameters Physical Measurements: •Dissolved Oxygen (DO) •Temperature •Transparency •Turbidity •Color •Conductivity Chemical Measurements: •pH •Hardness •Alkalinity •Total Phosphorus •Nitrates Dissolved Oxygen (DO) Depth (m ) Grap are QuickTim needed hics e™ deco toand se mpresso eathis picture. r 28- Jun-200 2 5- Aug- 2002 DO: Measurement of 12- Jul- 2002 12- Sep- 2002 concentration of O2 in water 0 column 1 2 3 Stratification leading to 4 5 anoxia 6 7 Phosphorus implications 8 9 10 11 Impact on fisheries 12 13 0 1 2 3 4 5 6 7 8 9 10 Disso lved O xygen (ppm) Transparency •Measures water clarity as an indicator of trophic state •Transparency less than 4 m indicates eutrophic conditions •September mean is 1.24 m •2001 mean is 2.8 m=Eutrophic Selected Test Results: (physical characteristics) Turbidity: Optical property-measures scattering and absorption of light 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 Physical Characteristic: Conductivity: ability of water to conduct electrical current Mean = 39.3 µMHOs/cm Maine avg is 20 to 40 µMHOs/cm Chemical Characteristic: Alkalinity: Capacity to neutralize acid High alkalinity can buffer against pH changes Mean = 37 ppm-good buffer Selected Test Results: (chemical tests) pH: Measure of acid balance of a solution Maine lakes range between pH 6.1 and pH 6.8 Healthy lakes range between pH 6-8.5 Webber Pond mean = 7.4 Hardness: Measure of total concentration of calcium and magnesium ions Mean = 2.91 ppm Soft 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 Epicore Concentration = 21.0 ppb Mean Surface Concentration = 19.4 ppb Mean Mid-depth Concentration = 19.9 ppb Mean Bottom Concentration = 79.4 ppb Fall Phosphorus Data Mean Epicore Concentration = 36.7 ppb Mean Surface Concentration = 35.7 ppb Mean Mid-depth Concentration = 34.6 ppb Mean Bottom Concentration = 191.0 ppb Spot Site Phosphorus Average 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 Phosphorus Mean Concentration = 81.5 ppb Watershed Land Use Patterns Chris 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 • Uses a common coordinate system • Combine geographic data with theme values and attributes • Creates layers of information for each theme www.esri.com GIS Inputs 1997 Digitized Aerial Photograph Classification of land use types (Agriculture) Final Product Completed 1997 Land Use Map Land Use Categories Natural Uses • Wetland Developmental Uses • Agriculture • Mature forest • Cleared • Transitional forest • Commercial / Municipal • Reverting land • 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 Mature Forest • Closed, continuous canopy • Best buffer from runoff and erosion • In 1997 covered 15.7% of watershed area Transitional Forests • At least 50% canopy cover • Provide some erosion prevention as well as water and nutrient absorption • In 1997 covered 49.7% of watershed Reverting Land • Land succeeding from agriculture towards forest • Results in a canopy cover of less than 50% • In 1997 covered 7.7% of watershed Cleared 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 Agriculture Cropland • Crop rows indicate planting • Addition of pesticides and fertilizers • In 1997, covered 9.1% of watershed Pasture • Agricultural land with no planting rows • Compaction leads to increased runoff • Presence of animal waste • Covered 4.7% of watershed Nutrient Management Plans Control amount of nutrients added to a field • 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 Maine Department of Agriculture (MDA) Commercial and Municipal Land • All businesses and public facilities • Impervious surfaces increase runoff • Less than 1% of watershed area in 1997 Golf Course • 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 Historic Trends in Land Use G are Q rap uickTim neede hics e™ deco d toand see mp re athis ssor p icture . M ature F orest Cleared O pen Residential Land Transitional Forest Agriculture O ther Reverting Forest Go lf C ourse We bbe r Pond 1997 We bbe r Pond 1956 0.8 7.12.8 3.4 35.9 17.7 15.7 13.8 7.7 2 9.6 49.7 34 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 Poor 10 – 15 Partial 16 – 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. House Count Data Shoreline NonShoreline Total Seasonal 93 17 110 YearRound 29 179 208 Unknown 31 0 31 •Total number of houses counted: 349 •Other Buildings and landuse noted: - School - Farms - Golf Course - Boat Storage - Tree Farms - Orchard - Nursery Subsurface Disposal Systems Town of Vassalboro Ordinances • 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 (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, 1974 Or • 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