Hey Chess,
I think we are largely stating the same thing in different ways. The important part is understanding and respecting what you can draw vs. how fast it can be refreshed, regardless of where and how it loops back into the environment.
For localized groundwater pumping, this is far more true compared to lake or river pumping.
I have yet to hear of a Canadian lake drawn down to the point of it turning to a swamp due to the use by a town or city.
Typically water levels decline more often due to changes in weather in a particular year. We have some groundwater recharge problems in communities south of the city that do not use the city water source. They are now working on management plans for those aquifers.
Inland aquifers need to be carefully managed more so than surface water sources, broadly speaking.
Interesting that you mention your water goes back into the system upstream of your water source.
I think you misunderstood.
Winnipeg water is drawn from Northern Ontario (Shoal Lake off the side of Lake of the Woods, a rather large lake even by Canadian standards).
From there it is pumped to Winnipeg, then treated and discharged into the Red River which heads north to Lake Winnipeg and eventually to Hudson Bay. Shoal Lake drainage flows north (it is above the Arctic Watershed line;
http://www.ontarioplaques.com/Plaques_STU/Plaque_Timiskaming04.html) and essentially is part of the same drainage basin as the Red River (Hudson Bay via Nelson).
http://atlas.nrcan.gc.ca/site/english/maps/environment/hydrology/drainagebasinsSo in a sense, the water removed from Shoal Lake for Winnipeg water use is taking a diverted route to end up in the Hudson Bay regardless.
So, in short, I never bit the bullet on geothermal. Also, we ran out of budget for the significant initial investment it added back then.
Friends of ours built a summer home in the Muskokas in the past 2 years. They have a newer geothermal system; glycol based, closed loop, using the lake as the thermal zone instead of having to dig into the earth. Expensive, yes. Works incredibly well and energy efficient, yes.
