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Geographic Information Systems and Modeling. Andrew Mckenna-Foster. Outline. What are Geographic Information Systems? Modeling with GIS Septic Suitability Model Erosion Potential Model. Geographic Information Systems.

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Presentation Transcript
  • What are Geographic Information Systems?
  • Modeling with GIS
  • Septic Suitability Model
  • Erosion Potential Model
geographic information systems
Geographic Information Systems
  • Visualization of geographic features and the corresponding physical attributes
    • Road map
    • Land use type
    • Soil map
    • Contour map
  • Modeling of natural processes using Arc GIS™ Spatial Analyst
modeling with gis
Modeling with GIS
  • Several input maps
  • Simulate factors that affect water quality
  • Septic suitability
  • Erosion potential
septic suitability model
Septic Suitability Model
  • What makes land suitable for septic systems?
    • Gentle slopes
    • Soil containing loam, sand, and gravel
  • Input maps:
    • Soil
    • Slope
soil map
Soil Map
  • Digitized polygons of the 17 soil types in the watershed
  • Septic suitability description
slope map
Slope Map
  • Ranked for suitability on a 1 to 9 scale:
    • Steep slope = 9
    • Gentle slope = 1
  • Range = 0o to 28o
  • Created from digital elevation maps
weighted overlay
Weighted Overlay



Septic Suitability








septic suitability results

Septic Suitability


Septic Suitability Results


  • 84% of watershed suitable
  • <1% unsuitable
  • Uses:
    • Guidance for proper system installation
    • Focus remediation efforts


erosion potential model
Erosion Potential Model
  • Displays
    • Erodibility of land in watershed
    • Potential effect erosion has on water quality
  • Accounts for proximity to the lakes and streams
  • 5 Input maps
    • Soil
    • Slope
    • Land Use Type
    • Proximity to lakes
    • Proximity to streams
slope and soil maps
Slope and Soil Maps
  • Same slope map
  • The soils were ranked for erodibility on a 1 to 9 scale based on K values
proximity maps


Proximity Maps







  • Lake proximity zones
    • 200 ft
    • 1,200 ft
  • Stream proximity zones
    • 200 ft









weighted overlay1
Weighted Overlay



Land Use

Lake Proximity

Stream Proximity











erosion potential results

Erosion Potential

Erosion Potential Results



  • Northeast corner has high impact
  • Wetlands are light gray
  • Useful for focusing remediation and erosion control efforts


summary of gis models
Summary of GIS Models
  • Septic suitability model
    • Functioning septic systems = better water quality
    • Guidance for proper septic placement and installation
  • Erosion potential model
    • Locates areas that contribute high erosion runoff
    • Focus remediation and control efforts for maximum increase in water quality
buffer strip and septic surveys results and remediation elizabeth turnbull

Buffer Strip and Septic Surveys: Results and RemediationElizabeth Turnbull



Shoreline Zoning Regulations

Development Survey

Buffer Strip Survey and Remediation - Septic Systems

- Septic Remediation

maine s residential shoreline zoning regulations
Maine’s Residential Shoreline Zoning Regulations
    • Structure height
    • Setback
    • Shore frontage
    • Area (ft2)
    • Total area of impervious surface
development assessment
Development Assessment
  • 5 Farms
  • 2 Gas Stations
  • Car Wash
  • Car Repair Garage
  • Motel
  • 2 Sand and Gravel Pits

560 total houses

  • 203 shoreline
  • 357 non-shoreline
  • 142 seasonal
  • 418 year-round

Well- buffered property

  • full lakeshore coverage
  • plants cover the entire area between the lake and the house
  • thick, diverse vegetation
  • riprap

Poorly buffered property

  • little vegetation
  • artificial beach
  • lawn mowed to shore
  • no deep root systems
buffer remediation
Avoid mowing to the shore

Native species

Duff layer


Winding paths

Any buffer is better than nothing

Buffer Remediation
wastewater disposal in threemile pond
Wastewater Disposal in Threemile Pond
  • Mostly septic systems
  • Common problems:
    • Too near the shore
    • Old
    • Grandfathered
    • Leaky
septic health
Compost- No Disposal

Conserve water- spread out use

Pump regularly

Replace when expanding and winterizing

Avoid dumping bleach or antibacterial substances

Avoid driving on leach field

Native plants

Low phosphate detergents and soaps

New development?

Septic Health
overview of selected watershed management
Overview of Selected Watershed Management
  • Sources
  • Road Survey
  • Agriculture
  • Household remediation
phosphorus budget
Phosphorus Budget
  • Determines the sources of phosphorus within the watershed
  • Starts with estimations and is adapted to findings
  • Determines the amount of phosphorus that each land type contributes
  • Influenced by area of each land use type
phosphorus inputs
Phosphorus Inputs

All Inputs

Cultural Inputs

road survey
Road Survey
  • Importance of road maintenance, camp roads in particular
  • Assessed all roads in watershed
crowning and grading
Crowning and Grading
  • Smooth surface and a crown that rises 1/2 inch for each foot of road width
  • Remove berms
  • Grade when appropriate
  • Collect and store storm water
  • Trapezoidal or parabolic
  • Vegetation
water diversions
Water Diversions
  • Water bars
  • Culverts
road assessment results
Road Assessment Results
  • 22 acres of camp roads
  • 74 acres of municipal or state roads
  • Camp roads in worst condition
  • Implications for Threemile Pond
other forms of remediation
Other Forms of Remediation
  • Agriculture
  • Household impacts
  • Potential impacts
  • Limit excessive use of fertilizers
  • Contour cultivation
  • Stubble mulching
  • Minimizing tillage
other remediation techniques
Other Remediation Techniques
  • Fertilizer use
  • Household products
  • Boat ramp
some watershed remediation techniques
Some Watershed Remediation Techniques
  • Maintain integrity of roads
  • Practice agriculture techniques that minimize phosphorus entering lakes
  • Be aware of household impacts
  • Importance of managing a watershed before looking to in lake remediation techniques
overview of remediation
Overview of Remediation
  • Remediation of Threemile Pond
  • Review of nonapplicable remediation techniques
  • Recommendations
  • Implementation in Threemile Pond
definition of lake remediation
Definition of Lake Remediation

“the manipulation of a lake ecosystem to effect an in-lake improvement in degraded or undesirable conditions”

~Dunst, et al. 1974

challenges for threemile pond remediation
Challenges for Threemile Pond Remediation
  • Multiple Towns
  • Non-point Sources
  • Nature of a lake system
  • Cost/benefit analysis
application to threemile pond
Application to Threemile Pond

Important to consider:

  • Technique requirements
  • Costs/benefits
  • How it specifically applies to Threemile Pond and its demands
common remediation techniques
Common Remediation Techniques
  • Dredging
  • Water removal techniques:
    • Hypolimnetic Withdrawal
    • Dilution
    • Drawdown
additional techniques

Temporary, toxic, expensive

Aquatic Plant Harvesting

Not enough phosphorus in biomass

Physical Liners

Application is difficult & expensive, lake size

Additional techniques
potential techniques for threemile pond
Potential Techniques for Threemile Pond
  • Wetland Maintenance
  • Alum Treatment
  • Hypolimnetic Aeration
  • Biological control through fish stock manipulation
alum treatment
  • Chemically inactivates phosphorus
  • Learn from previous treatment
    • Inadequate application
    • Buffering agent
  • More advanced technology
    • GPS and GIS to map areas of lake for specific application
Ideal tool for determining alum treatment application

Anoxic depth & alum treated area map

Bathymetry map

biological control fish stock manipulation
Decrease planktivorous fish

Discontinue stocking of alewives

Increase piscivorous fish

Continue/Increase stocking of brown trout

Stock small & large mouth bass

Biological Control: Fish Stock Manipulation

Inexpensive and less ecologically damaging

implementation in threemile pond
Implementation in Threemile Pond
  • Alum treatment, hypolimnetic aeration, and fish stock manipulation are promising
  • Methods worth further consideration and study
  • Consider implementation for improvement
emily arell

Emily Arell

Future Predictions and

Recommendations for Threemile Pond

historic and future development trends
Historic and Future Development Trends
  • Agriculture will continue to decline
  • Demand for housing and development will continue to rise
    • Shoreline property
    • Subdividing of existing lots
prediction of land use changes by 2040
Cleared land

Transitional forest





Mature forest












Prediction of Land Use Changes by 2040
watershed management
Watershed Management
  • Maintenance of septic systems
  • Create Buffer strips
  • Follow shoreline zoning regulations
  • Maintain integrity of roads
  • Practice agriculture techniques that minimize phosphorus entering lakes
  • Be aware of household impacts
in lake remediation techniques
In-lake Remediation Techniques
  • External phosphorus loading must be addressed prior to in-lake treatment for successful remediation
  • Possible Techniques for Threemile Pond:

1) Biological control through fish stock manipulation

2) Alum treatment

3) Hypolimnetic aeration

threemile pond remediation summary
Threemile Pond Remediation Summary
  • Assess lakes individually
  • Small changes can have a BIG effect
  • Address as many problems as possible
  • Establish a balance
    • Social
    • Economic
    • Environmental
water quality monitoring
Water Quality Monitoring
  • Water monitoring throughout summer-Characterization sites: 1, 2, 3
    • Transparency: bi-weekly
    • Dissolved Oxygen: bi-weekly
    • Phosphorus: test surface and

epicore monthly

  • Community volunteers
community awareness and education
Community Awareness and Education
  • Work closely with the China Region Lakes Alliance and Threemile Pond Association
  • Distribute fact sheets and brochures
  • Provide information in town offices and schools
  • Involve local schools in monitoring Threemile Pond
grants and funding
Grants and Funding
  • Maine DEP website
    • Non-point source Water Pollution Control Grants
    • Non-governmental funding sources
    • Watershed Protection Grant
  • Maine Natural Resource Protection Act
general summary
General Summary
  • The primary problem in Threemile Pond is cultural eutrophication
    • Remediation must consider all sources of phosphorus runoff
  • Water quality will improve with:
    • Reduction of external phosphorus loading
    • Reduction of sediment release of phosphorus
threemile pond
Threemile Pond
  • Remediation means the preservation of:
    • Environmental Health
    • Economic Viability
    • Cultural History
special acknowledgments
Special Acknowledgments
  • George Gunning
  • Bill Woodward
  • Russell Cole
  • Dave Firmage
  • Dan Tierney
  • Roy Bouchard
  • Dave Halliwell
  • Rebecca Manthy
  • Jenna Richardson
  • Nate Sylvester
  • Dan Dubord

The staff at the China Town Office

The staff at the Vassalboro Town Office

The staff at the Windsor Town Office