| Section 2: Outline |
| Erosion and Septic Suitability Models | |
| Water Chemistry Analysis | |
| Recommendations | |
| Questions & Answers |
| GIS Modeling: Erosion Potential Septic Suitability |
| Phoebe Lehmann |
| Erosion Potential |
| Modeling with GIS |
Erosion Potential: Combination of Factors in GIS |
| Slope + Soil Type + Land Use |
| Slide 5 |
| Slide 6 |
| Slide 7 |
| Slide 8 |
| Slide 9 |
| Slide 10 |
| Slide 11 |
| Slide 12 |
| Erosion Potential Conclusions |
| Consider high erosion potential areas when planning development | ||
| Take proper measures to decrease erosion potential: | ||
| Plant native shrubs and trees (especially on high percent slope areas) | ||
| Improve buffer strips along lake shore | ||
| Septic Suitability |
| Modeling with GIS |
| Slide 15 |
| Slide 16 |
| Septic Suitability Conclusions |
| Areas with poor septic suitability have high installation costs | |
| Implement consistent monitoring of all septic systems |
| Water Quality |
| Water budget | |
| Water quality parameters | |
| Phosphorus loading model |
| Water Budget |
| Lake Wesserunsett Flushing Rate: | |
| 1.09 flushes/year |
| Water Quality Assessment |
| Dissolved Oxygen | |
| Temperature | |
| Alkalinity | |
| pH | |
| Turbidity | |
| Color | |
| Conductivity | |
| Nitrates | |
| Hardness | |
| Transparency | |
| Phosphorus | |
| Dissolved Oxygen & Temperature |
| Buffering and pH |
| pH | |
| Measure of hydrogen ions on a log scale | |
| Mean pH: 7.46 | |
| Sample size (n)=20 | |
| Approximately neutral | |
| Alkalinity | |
| Acid neutralizing capacity of water | |
| Alkalinity for Lake Wesserunsett: 280 meq/l | |
| Adequate buffering |
| Additional Water Quality Tests |
| Turbidity | |
| 0.97 NTU | |
| n=11 | |
| True Color | |
| 10 SPU | |
| n=8 |
| Hardness |
| Concentration of Ca2+ and Mg2+ | ||
| 3.24 mg/l | ||
| n=4 | ||
| Very soft water | ||
| Transparency |
| Measures water clarity | |
| 5.4 m, n=9 | |
| Less than 2 m indicates algal bloom |
| Phosphorus |
| Limiting nutrient | |||
| Typical algal bloom range: 12-15 ppb | |||
| 2000 mean: 12.0 ppb, n=52 | |||
| Spring: 10.0 ppb | |||
| Summer: 15.6 ppb | |||
| Fall: 10.1 ppb | |||
| Summer Phosphorus Sources |
| Seasonal recreational activity | |
| 68% shoreline residential is seasonal | |
| Decreased flushing rate | |
| Increase in decomposition | |
| Implications |
| Increased probability of algal blooms | ||
| Decrease in dissolved oxygen | ||
| Fish kills | ||
| Aesthetic degradation | ||
| Phosphorus Loading Model |
| Predicts phosphorus concentrations | |||
| Land use and development | |||
| Export coefficient | |||
| Land area | |||
| Calculated phosphorus level: 12.5 ppb | |||
| Predicts future concentrations | |||
| Slide 30 |
| Slide 31 |
| Future Predictions |
| 15% increase in road area | ||
| Development of remaining shoreline lots | ||
| 13.4 ppb | ||
| Water Quality Conclusions |
| Stable Conditions | |
| Water clarity | |
| Nitrates low | |
| pH neutral | |
| Buffering adequate | |
| Areas of Concern | |
| Very soft water | |
| Phosphorus at threshold for algal blooms |
| Lake Wesserunsett Conclusions and Recommendations |
| Lake Wesserunsett Conclusions |
| Phosphorus concentrations are a real concern for the lake | ||
| The following contribute to phosphorus loading: | ||
| Shoreline construction and development | ||
| Runoff from roads/clear lands | ||
| Inadequate shoreline buffering | ||
| Septic system leaching | ||
| Dense populations in shoreline area | ||
| Destruction of wetlands | ||
| Areas of Recommendation |
| Development | |
| Lake water quality | |
| Phosphorus | |
| Awareness |
| Development Recommendations |
| Construct/renovate residences according to ordinances | |
| Improve buffer strips | |
| Repair risk and high risk roads | |
| Enforce septic regulations | |
| Prevent shoreline erosion |
| Lake Water Quality Recommendations |
| Reduce phosphorus loading | |
| Monitor phosphorus concentrations | |
| Prevent invasive plant species | |
| Maintain/monitor fish health and abundance |
| Awareness Recommendations |
| Information sources | |
| Local school curriculum | |
| Community workshops | |
| Lake Association | |
| Acknowledgements |
| Russell Cole, David Firmage, Philip Nyhus and Bernadette Graham (Colby College) | |
| Roy Bouchard and Karen Hahnel (DEP) | |
| William Reid, William Pottle, Charlie Christian, Beverly Fitzsimmons, Tim McDonald, Nate Sylvester, Art and Sue McDonald, Alexander Turbyne | |
| Jim Stahlnecker, Matt O’Donnell, Forrest Bonney, Dana Murch, David Boucher, Barry Mower, Bob Nelson, Tiffany Michaud | |
| Maine Departments of Envrionmental Protection, Inland Fisheries and Wildlife, and Human Services | |
| Madison Town Office | |
| Somerset County Soil and Water Conservation District | |
| Slide 41 |