Aquifer System

Localisation

Oak Ridges Moraine


Lower deposits aquifer
Lower sediment is formed of poorly exposed, interbedded lake sediment and till. It comprises sand, silt, clay, till, and distinctive organic-rich and fossil-bearing beds. The unit overlies the bedrock and is covered by Newmarket Till, Oak Ridges Moraine sediments and Halton Till. The aquifer is confined by the Newmarket Till aquitard. However, the till is incised and sometimes eroded entirely, resulting in local high-conductivity windows between upper and lower aquifer systems. The unit is characterized by sandy formations with good hydraulic conductivity and aquifer potential. Lower sediment hosts a number of key regional aquifers that have prolific yields; however, the aquifer-aquitard system is poorly known. A part of the groundwater percolating through Oak Ridges Moraine sediments recharges lower sediments aquifers. In the lower sediments, groundwater discharges as springs along deep river valleys where the river has eroded into or beneath the Newmarket Till or it can migrate through the complete sediment column to discharge at Lake Ontario. Lower sediments groundwater is used for municipal water supply and transmits inter-watershed flow. Groundwater quality is good, however the lowest formation of the unit may have water-quality problems related to methane and dissolved organic carbon.
Newmarket Till aquitard
In ascending order, the stratigraphic units of the Oak Ridges Moraine are: Paleozoic bedrock, Lower deposits, Newmarket Till, Oak Ridges Moraine sediments, and Halton till. Newmarket till forms an areally extensive sheet, the upper contact of which is a highly irregular erosional surface marked by incised channels and drumlins. Newmarket till is a thick aquitard, characterized by low hydraulic conductivity. Flow through the Newmarket Till aquitard is attributed primarily to interconnections among various heterogeneities of the unit. Flow within the diamicton matrix itself is considered to be minor. In some places, the till is incised, and sometimes eroded entirely, by a network of sand- and gravel-filled channels forming productive aquifers. The sediments filling the channels are Oak Ridges sediments. In other places, the channels breach the till entirely and form high-conductivity windows connecting upper and lower aquifer systems.
Oak Ridges Moraine sediments aquifer
In ascending order, the stratigraphic units of the Oak Ridges Moraine (ORM) are: Paleozoic bedrock, Lower deposits, Newmarket Till, Oak Ridges Moraine sediments, and Halton Till. Oak Ridges Moraine sediments overlie a regional unconformity (cut on Newmarket Till) with infill tunnel channels and forms a prominent east-west ridge. Channels infill with coarse glaciofluvial sediments form prolific regional aquifers. ORM sediments consist mostly of silt and fine sand, but also include large gravel seams and minor clay and diamicton. The aquifer is unconfined, except where it underlies Halton Till. Hydraulic conductivity is good and the aquifer potential is one of the highest of the country. ORM sediment forms a major recharge area. Water percolates (200-400mm/ yr) through the moraine ridge and mostly discharges from dozens of headwater stream springs sourced in the ORM. Groundwater that does not discharge from headwater stream springs can move deeper through the ORM into lower aquifers, then discharge as springs along deep river valleys where the river has eroded into or beneath the Newmarket Till. It can also migrate through the complete sediment column to discharge at Lake Ontario. These discharge pathways are controlled by the distribution of permeable channel and subaqueous fan structures, by confining aquitards, and by regional gradients with up to 300 m head differential to Lake Ontario. The ORM sediment aquifer is exploited for domestic uses due to high yields and good water quality.
Halton Till aquitard
In ascending order, the stratigraphic units of the Oak Ridges Moraine are: Paleozoic bedrock, Lower deposits, Newmarket Till, Oak Ridges Moraine sediments, and Halton till. The latter is predominantly a massive to laminated mud unit with low stone count and local interbeds of sand and gravel. Along the upper flanks of the ORM the unit is 1-5 m thick and southward can increase in thickness up to 30 m. Halton Till forms a discontinuous aquitard. This low permeability unit partially confines ORM aquifers and restricts recharge. Groundwater is fresh, but very hard. Iron concentrations are above the aesthetic objective.
Source Project Datasets More info
Oak Ridges MoraineOak Ridge morain rechargeRaster Dataset
Oak Ridges MoraineOakridge Moraine groundwater compositionVector Dataset
Oak Ridges MoraineOakridge Moraine groundwater samplesVector Dataset
Oak Ridges MoraineOakridge Moraine groundwater levelVector Dataset
Oak Ridges MoraineOakridge Moraine hydrogeological unitsVector Dataset
Oak Ridges MoraineOakridge Moraine surficial geologyVector Dataset
Oak Ridges MoraineOakridge Moraine bedrock geologyVector Dataset
Oak Ridges MoraineOak Ridge Moraine vulnerabilityRaster Dataset
Project Publication More info
Geoscape Toronto
Géopanorama de Toronto
Oak Ridges MoraineThe role of GIS and expert knowledge in 3-D modelling, Oak Ridges Moraine, southern Ontario
Structural model of the Greater Toronto and Oak Ridges Moraine areas, southern Ontario: ORM sediment
Structural model of the Greater Toronto and Oak Ridges Moraine areas, southern Ontario: Halton Till
Structural model of the Greater Toronto and Oak Ridges Moraine areas, southern Ontario: Newmarket Till
Structural model of the Greater Toronto and Oak Ridges Moraine areas, southern Ontario: Lower sediment
Oak Ridges MoraineApplication of seismic stratigraphy and sedimentology to regional hydrogeological investigations: an example from Oak Ridges Moraine, southern Ontario, Canada
Oak Ridges MoraineTowards improved hydrogeologic conceptual models in the St. Lawrence Lowlands of southern Ontario
Toward improved understanding of aquifer heterogeneity: a case study from the Lake Simcoe Regional Conservation Authority, Southern Ontario
Oak Ridges MoraineGeological frameworks in support of source water protection in Ontario
Oak Ridges MoraineRegional groundwater flow modeling in the Oak Ridges Moraine area: building on the 3D geologic model
Oak Ridges MoraineA framework for buried-valley aquifers in southern Ontario
Regional 3-D structural model of the Oak Ridges Moraine and Greater Toronto Area, southern Ontario: version 2.1
Regional 3-D structural model of the Oak Ridges Moraine and Greater Toronto Area, southern Ontario: version 2.1
Oak Ridges MorainePontypool 'Golden Spike' borehole data compilation
Oak Ridges Moraine
Oak Ridges MoraineSediment-aquifer play types in a list of 30 key Canadian aquifers
Oak Ridges MoraineRegional hydrogeological studies: the value of data collected from continuously cored boreholes
Oak Ridges MoraineStratigraphic architecture and sediment facies of the western Oak Ridges Moraine, Humber River watershed, southern Ontario
Oak Ridges MoraineRegional unconformities and the sedimentary architecture of the Oak Ridges Moraine area, southern Ontario
Oak Ridges MoraineGeostatistical mapping of leakance in a regional aquitard, Oak Ridges Moraine area, Ontario, Canada
Oak Ridges MoraineOn the origin of the Oak Ridges Moraine
Oak Ridges MoraineStandardization and assessment of geological descriptions from water well records, Greater Toronto and Oak Ridges Moraine areas, southern Ontario
Tunnel channels of the Greater Toronto and Oak Ridges Moraine areas, southern Ontario
Tunnel channels of the Greater Toronto and Oak Ridges Moraine areas, southern Ontario
Oak Ridges MoraineGroundwater discharge in the Humber River watershed
Oak Ridges MoraineGroundwater discharge in the Humber River watershed
Oak Ridges MoraineUsing downhole geophysical logs to provide detailed lithology and stratigraphic assignment, Oak Ridges Morain, southern Ontario
Oak Ridges MoraineUsing downhole geophysical logs to provide detailed lithology and stratigraphic assignment, Oak Ridges Morain, southern Ontario
Oak Ridges MoraineSouthern Ontario "Golden Spike" data release: Nobleton borehole
Oak Ridges MoraineSouthern Ontario "Golden Spike" data release: Nobleton borehole
Oak Ridges MoraineThe need for basin analysis in regional hydrogeological studies: Oak Ridges Moraine, southern Ontario
Oak Ridges MoraineThe need for basin analysis in regional hydrogeological studies: Oak Ridges Moraine, southern Ontario
Oak Ridges MorainePontypool 'golden spike' borehole digital data compilation: sedimentology and geophysical data
Oak Ridges MorainePontypool 'golden spike' borehole digital data compilation: sedimentology and geophysical data
Oak Ridges MoraineThe significance of buried valleys to groundwater systems in the Oak Ridges Moraine region, Ontario: extent, architecture, sedimentary facies and origin of valley settings in the ORM region
Oak Ridges MoraineThe significance of buried valleys to groundwater systems in the Oak Ridges Moraine region, Ontario: extent, architecture, sedimentary facies and origin of valley settings in the ORM region
A 3-dimensional geological model of the Oak Ridges Moraine area, Ontario, Canada
A 3-dimensional geological model of the Oak Ridges Moraine area, Ontario, Canada
Oak Ridges MoraineOn the kriging of water table elevations using collateral information from a digital elevation model
Oak Ridges MoraineOn the kriging of water table elevations using collateral information from a digital elevation model
Oak Ridges MoraineHydraulic-jump and hyperconcentrated-flow deposits of a glacigenic subaqueous fan: Oak Ridges Moraine, southern Ontario, Canada
Oak Ridges MoraineHydraulic-jump and hyperconcentrated-flow deposits of a glacigenic subaqueous fan: Oak Ridges Moraine, southern Ontario, Canada
Oak Ridges Moraine
Oak Ridges Moraine
Oak Ridges MoraineThe role of GIS and expert knowledge in 3-D modelling, Oak Ridges Moraine, southern Ontario
Oak Ridges MoraineThe role of GIS and expert knowledge in 3-D modelling, Oak Ridges Moraine, southern Ontario
Oak Ridges MoraineStandardization and assessment of geological descriptions from water well records, Greater Toronto and Oak Ridges Moraine areas, southern Ontario
Hydrogeology of the Oak Ridges Moraine aquifer system: implications for protection and management from the Duffins Creek watershed