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The State of Webber Pond

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

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The State of Webber Pond

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  1. 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

  2. Presentation Overview Introduction Water Quality Analysis Land Use Analysis - Intermission - GIS Analysis and Models Future Predictions Remediation Measures Recommendations

  3. An Introduction to the Study of Webber Pond Erin Estey

  4. 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.

  5. 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

  6. 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

  7. 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 A Webber Pond Sunset

  8. Lake Strata

  9. Lake Turnover • Webber Pond is dimictic • Summer thermocline • Fall turnover • Winter stratification • Spring turnover • Turnover re-oxygenates the lake, recycles nutrients

  10. Trophic Status of Lakes

  11. 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.

  12. Defining a Watershed • Total area contributing flow to a particular basin. • Defined as the highest points of land that surround it.

  13. 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.

  14. The Webber Pond Dam 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

  15. 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

  16. 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)

  17. 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

  18. 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)

  19. Water Chemistry Serena Vayda

  20. Sample Site Locations 3 characterization sites 7 spot sites 4 tributary sites

  21. 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

  22. Water Quality Parameters • Chemical Measurements: • pH • Hardness • Alkalinity • Total Phosphorus • Nitrates • Physical Measurements: • Dissolved Oxygen (DO) • Temperature • Transparency • Turbidity • Color • Conductivity

  23. Dissolved Oxygen (DO) DO: Measurement of concentration of O2 in water column Stratification leading to anoxia Phosphorus implications Impact on fisheries

  24. 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

  25. Selected Test Results: (physical characteristics) Turbidity: Color: Optical property-measures scattering and absorption of light in water column Contributes to depth that light can penetrate water Mean = 18.5 SPU Webber Pond mean = 5.89 NTU Comparable to other lakes in region Natural waters <50 NTU

  26. Physical Characteristic: Chemical Characteristic: Conductivity: ability of water to conduct electrical current Alkalinity: Capacity to neutralize acid High alkalinity can buffer against pH changes Mean = 37 ppm-good buffer Mean = 39.3 µMHOs/cm Maine avg is 20 to 40 µMHOs/cm

  27. Selected Test Results: (chemical tests) Hardness: Measure of total concentration of calcium and magnesium ions 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 Mean = 2.91 ppm Soft lake Good for fish, vulnerable to algae blooms and phosphorus loading Webber Pond mean = 7.4

  28. Nutrient Levels Paul Mathewson

  29. Nutrient Loading • Plants need a variety of essential nutrients for growth • Phosphorus and nitrogen limiting in aquatic ecosystems • Cultural Eutrophication

  30. 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

  31. Historical Phosphorus Mean Concentration = 28.2 ppb

  32. 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

  33. 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

  34. Spot Site Phosphorus Average Concentration = 30.6 ppb

  35. Sediment Release • Phosphorus accumulation in hypolimnion • Oxygenated water: ferric phosphate • Anoxic conditions: phosphorus release

  36. Epicore and Bottom Phosphorus Concentrations in 2002

  37. Historical Epicore and Bottom Phosphorus Concentrations Mean Epicore Concentration = 29.5 ppb Mean Bottom Concentration = 249.8 ppb

  38. 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

  39. 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

  40. Tributary Phosphorus Mean Concentration = 81.5 ppb

  41. Watershed Land Use Patterns Chris Makarewich

  42. 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

  43. Steps in Creating the Land Use Map • Obtain Digital Orthophoto Quads • Import into ArcView 3.2 (GIS computer program) • Determine land use categories • Digitize land use areas through polygons • 5. Derive and summarize areas

  44. 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

  45. GIS Inputs

  46. 1997 Digitized Aerial Photograph Classification of land use types (Agriculture)

  47. Final Product Completed 1997 Land Use Map

  48. Land Use Categories • Developmental Uses • Agriculture • Cleared • Commercial / Municipal • Golf Course • Open Residential Land • Natural Uses • Wetland • Mature forest • Transitional forest • Reverting land

  49. Wetlands • Transition from aquatic to terrestrial ecosystems • Natural buffer against nutrients and sediments • In 1997 covered 0.5% of watershed area

  50. Mature Forest • Closed, continuous canopy • Best buffer from runoff and erosion • In 1997 covered 15.7% of watershed area

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