Hydrology
The Oak Ridges Moraine's hydrological system is a major constituent of the Humber Watershed, so that any impact on this system will be of concern. A specific concern is urbanization, which affects water quality by increasing its load of metals and organic contaminants. A study by Cook et al. (1985) found an increase in mean annual runoff, instantaneous discharge, and hydrograph peak flow as a result of urbanization: "...changes in land use coincided with changes in volumetric and time distribution aspects of hydrologic response."
Numerous watersheds are linked to the Oak Ridges Moraine, and are managed by various organizations.
| Watershed | Conservation Authority |
|---|---|
| Nottawasaga River | Nottawasaga Valley Conservation Authority |
| Credit River | Credit Valley Conservation |
| Holland River | Lake Simcoe Region Conservation Authority |
| Black River | Lake Simcoe Region Conservation Authority |
| Pefferlaw Brook | Lake Simcoe Region Conservation Authority |
| Humber River | Toronto and Region Conservation Authority |
| Don River | Toronto and Region Conservation Authority |
| Rouge River | Toronto and Region Conservation Authority |
| Duffins Creek | Toronto and Region Conservation Authority |
| Nonquon River | Kawartha Conservation |
| Scugog River | Kawartha Conservation |
| Pigeon River | Kawartha Conservation |
| Lynde Creek | Central Lake Ontario Conservation Authority |
| Oshawa Creek | Central Lake Ontario Conservation Authority |
| Bowmanville and Soper Creeks | Central Lake Ontario Conservation Authority |
| Trout Creek | Otonabee Region Conservation Authority |
| Wilmot Creek | Ganaraska Region Conservation Authority |
| Ganaraska River | Ganaraska Region Conservation Authority |
| Gage Creek | Ganaraska Region Conservation Authority |
| Cobourg and Baltimore Creeks | Ganaraska Region Conservation Authority |
(Note: the above table excludes watersheds managed by the Lower Trent Conservation Authority.)
Read more about this topic: Hydrography Of The Oak Ridges Moraine