Sustainability and the Mahomet Aquifer

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Sustainability and the Mahomet Aquifer
WMRC Seminar Series on Sustainability January 16,
2008

• Allen Wehrmann, P.E., P.H.(GW), D.WRE, Director
• Center for Groundwater Science, Illinois State
  Water Survey

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Special thanks to
Ed Mehnert Hydrogeology Section Illinois State
Geological Survey
George Roadcap Derek Winstanley Illinois State
Water Survey
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The Mahomet Aquifer Region
Watseka
WOODFORD CO
Peoria
NORTH
Morton
FORD CO
Normal
IROQUOIS CO
Pekin
Gibson City
Hoopeston
Bloomington
Paxton
TAZEWELL CO
CHAMPAIGN CO
VERMILION CO
MCLEAN CO
Havana
Rantoul
Mahomet
MASON CO
LOGAN CO
Danville
DEWITT CO
Clinton
Urbana
Lincoln
Champaign
MENARD CO
PIATT CO
CASS CO
Monticello
Petersburg
MACON CO
Bedrock high aquifer absent
Decatur
Proposed ethanol plants using Mahomet Aquifer as
principal source
Springfield
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Sustainability
the ability to meet the needs of the present
generation without compromising the ability of
future generations to meet their needs. United
Nations Brundtland Commission, 1987
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Groundwater Sustainability
development and use of groundwater in a manner
that can be maintained for an indefinite time
without causing unacceptable environmental,
economic, or social consequences. USGS
Circular 1186, 1999
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The Hydrologic Cycle Climate, surface water, and
groundwater are linked
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Porous Systems
Porosity volume of pore space / total volume of
porous material
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Aquifers vs. Aquitards
An aquifer is a saturated bed, formation, or
group of formations which yields water in
sufficient quantity to be of consequence as a
source of supply.
An aquitard yields inappreciable quantities of
water to wells compared to an aquifer but
through which leakage of water is possible.
Aquitards often act as confining beds.
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Unconfined vs. Confined Groundwater
An unconfined aquifer is one in which
groundwater possesses a free surface open to the
atmosphere. The upper surface of the zone of
saturation is called the water table.
A confined aquifer is one in which groundwater
is confined under pressure by overlying and
underlying aquitards or aquicludes and water
levels in wells rise above the top of the
aquifer. Also called an artesian aquifer.
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Unconfined Aquifers
Land Surface
Unsaturated (Vadose) Zone
Water Table
Saturated Zone
Unconfined Aquifer
Bedrock
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Confined Aquifers
Land Surface
Unsaturated (Vadose) Zone
Water Table
Unconfined Aquifer
Saturated Zone
Potentiometric Surface
Confining Layer - Aquitard
Confined Aquifer
Bedrock
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Confined Aquifers Artesian Wells
Flowing artesian well
Land surface
Water table
Aquifer
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Groundwater Stream Interaction
Regional Flow Systems
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Groundwater Stream Interaction
Regional Flow Systems
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Groundwater Stream Interaction
Regional Flow Systems
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Groundwater Stream Interaction
Regional Flow Systems
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Regional Bedrock Topography
Green higher elevations Light violet lower
elevations
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The Mahomet Aquifer Region
Watseka
WOODFORD CO
Peoria
NORTH
Morton
FORD CO
Normal
IROQUOIS CO
Pekin
Gibson City
Hoopeston
Bloomington
Paxton
TAZEWELL CO
CHAMPAIGN CO
VERMILION CO
MCLEAN CO
Havana
Rantoul
Mahomet
MASON CO
LOGAN CO
Danville
DEWITT CO
Clinton
Urbana
Lincoln
Champaign
MENARD CO
PIATT CO
CASS CO
Monticello
Petersburg
MACON CO
Bedrock high aquifer absent
Decatur
Proposed ethanol plants using Mahomet Aquifer as
principal source
Springfield
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Illinois Geologyglacial materials
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Glacial Depositional Processes
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Geology of the Mahomet Aquifer
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Vertical Slice along the Mahomet Valley Thalweg
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Major Sand Gravel Aquifers
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Withdrawals from Sand Gravel Aquifers
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Regional Community Groundwater Use
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Cone of Depression
Well/Aquifer Interactions
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Overlapping Cones of Depression Well Interference
Well/Aquifer Interactions
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Overlapping Cones of Depression Well Interference
A
B
Well/Aquifer Interactions
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Overlapping Cones of Depression Well Interference
B
A
Well/Aquifer Interactions
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Overlapping Cones of Depression Well Interference
B
A
Well/Aquifer Interactions
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Overlapping Cones of Depression
Well/Aquifer Interactions
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Mahomet Aquifer Groundwater Levels
550
580
680
610
10-foot contour
Flow direction
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Mahomet Water Levels by the Illinois River
Land Surface 485 MSL elevation
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(No Transcript)
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Potentiometric Surface of Eastern Mahomet
Aquifer, 2005
Rantoul
Champaign-Urbana
Danville
Monticello
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Mahomet Potentiometric Heads near Champaign
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Water Use Trend at Champaign
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Withdrawals vs. Head in Mahomet Aquifer near
Champaign
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Impacts of pumping on water levels (head)
High-capacity well
Low-capacity well
Glacial till

P
P
P
Mahomet aquifer
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Impact of pumping hydraulically linked aquifers
Glacial Till
P
Dewatered aquifer
Glasford Aquifer
P
Glacial Till
P
Mahomet Aquifer
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Interaquifer Connections to the Sangamon River
Mahomet nonpumping head
Glasford nonpumping head
Glasford pumping head
Mahomet pumping head
Decatur 2
Glacial Till
SangamonRiver
Glasford Aquifer
Glacial Till
Mahomet Aquifer
Well/Aquifer Interactions
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Vertical Slice along the Thalweg
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ISWS Regional Flow Model Predicted Heads
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Mahomet Aquifer 1890-1940 (1920s)
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Drawdown near Champaign 1920s - 2005
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Potentiometric Surface of the Glasford Aquifer
2007
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Glasford Mahomet Head Difference
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Observation Wells near Champaign
Existing
New
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Model-Predicted Drawdown Q 23 mgd at Champaign
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The Mahomet Aquifer Region
Watseka
WOODFORD CO
Peoria
NORTH
Morton
FORD CO
Normal
IROQUOIS CO
Pekin
Gibson City
Hoopeston
Bloomington
Paxton
TAZEWELL CO
CHAMPAIGN CO
VERMILION CO
MCLEAN CO
Havana
Rantoul
Mahomet
MASON CO
LOGAN CO
Danville
DEWITT CO
Clinton
Urbana
Lincoln
Champaign
MENARD CO
PIATT CO
CASS CO
Monticello
Petersburg
MACON CO
Bedrock high aquifer absent
Decatur
Proposed ethanol plants using Mahomet Aquifer as
principal source
Springfield
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East-Central Illinois Water Supply Planning Area
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The Hydrologic Cycle
A physical and biological framework for regional
water supply planning management
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How to Manage Regional Water Supplies?

• Business as usual? Rule of Reasonable Use
• Change?
• Many pieces to the puzzle supply, demand,
  impacts of withdrawals, surface water
  groundwater interaction, water quality,
  conservation, reuse, climate change, droughts,
  planning time horizons, economics

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Illinois Groundwater Law

• Rights are usufructuary meaning one has the
  right to use the water, as opposed to
  proprietary meaning rights of ownership.
• We can use the water, we do not own the water.
• Riparian Doctrine of Reasonable Use brings
  surface water and groundwater use law together

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Illinois Groundwater Law

• A landowner has the right to make any
  reasonable use of groundwater as long as it
  relates to some beneficial activity on the
  overlying land even though significant
  interference might result to groundwater supplies
  of adjacent landowners
• In practice, an affected landowner has the right
  to sue for damages or interruption of supply and
  the court will decide on the reasonableness of use

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How to Manage Regional Water Supplies?

• Previously not had a process or structure for
  regional planning management
• Governors E.O. 2006-01 established such an
  administrative process structure
• The East-Central Illinois Regional Planning
  Committee will need to develop a framework for
  making their management recommendations
• The concept of sustainability is a potential
  framework

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