"Wasting" Water? (drawn from a lake)
I am trying to get the details on my local water system (as JMG recomments in Green Wizardry) and wondering if any of you who are well versed in these issues could weigh-in on my thoughts on the issue.
I live in an area that draws it's potable water from a lake. (Winnipeg, MB, drawing its water from Shoal Lake, within the same province.)
As far as I know, the water is brought to the city by an aqueduct that uses mostly gravity to bring it to the city.
People admonish against "wasting water" but as far as I can see it, the ecological harms that come from wasting water in this situation are:
1) The chemicals that are used to treat water to enter the potable water system, and the chemicals that are used to treat wastewater, before expelling it into our local rivers, the Assiniboine and the Red River. I've read that, especially if these treatment chemicals are based on chlorine, they can cause damage to the environment.
2) The energy that is used to keep a municipal pressure at the faucets. I'm guessing that it takes a certain amount of electricity to pump the water to a certain pressure within a building, and whenever one opens a faucet, that causes a little bit of extra amperage to flow through a variable pump to maintain the city pressure, but I'm not sure if that is the case.
Aside from that, I can't see any harm from drawing water from a lake, and expelling the treated wastewater into local rivers. I did once see a documentary regarding bottled water, that claimed that removing a certain amount of water from a watershed, bottling it, and transporting it over far distances caused damage to that watershed, but I'm thinking the close distances from lake to city in this case don't fall under that reasoning.
I know that in this province we have a problem of excess nitrogen entering the rivers (and lakes, downstream) but I think we may have tackled this problem: we used to spray our sewage sludge on agricultural fields, but in 2014 (I think) we outlawed that, and required the sludge to be put in landfills, with a pilot project of at minimum 20% of our sewage sludge being composted and then added to agricultural fields, to avoid the runoff. Hopefully they ramp up the program to compost 100% our sewage sludge to be composted.
I can certainly see the argument against wasting water where a municipality is drawing from an aquifer that is replenishing much slower than water is being removed from it: the slower your city/town can draw water from the aquifer, the longer that you can survive on the water that the aquifer provides.
I think in my local case, the indigenous people living around the lake that my city draws it from do not have potable water, which is ironic, though I'm not sure that our drawing water from that lake makes their situation any worse.
I'm just wondering if I've accounted for all the variabilities that are a part of the water system I'm living within: the main drawbacks to excess usage are the chemicals used for treating the water, and energy used for maintaining pressure?
Apologies for the long question again, just wondering if anyone with knowledge on these issues would be willing to sift through my situation. Thx!