Q: As I see it, water from the rivers flows into the water system, travels through pipes to my house, washes dishes, washes me, etc., goes into the sewer system, is treated at the sewage treatment plant, and goes back into the river. I understand that some volume may be lost to evaporation and leakage, but how does a low-flow showerhead, toilet, etc., actually save water? It goes back into the river eventually, right? – Tom Smith, Sacramento
A: That’s assuming the rivers and your home are part of a closed loop with a relatively constant water supply; they are not. Taking water from the mountains, the rivers are always flowing toward the sea. The water you take out of the river is not the same water you put back. We’re constantly tapping into the river’s fresh supply from the mountain snowpack. When there’s no snow, that fresh supply is limited. That’s where we are right now.
As of Jan. 30, Sierra Nevada snowpack was 12 percent of average for the date, the smallest snowpack ever recorded at this point in winter, according to a Department of Water Resources survey. No snow means no fresh water for the rivers – and no water for your home. That’s why saving fresh water makes a difference; there’s less right now to go around. Although it may fall from the sky, fresh water is a finite resource and we’re trying to make it stretch.
Yes, some water is put back into the rivers after use, but it flows to users downstream. They need water, too. And right now, the rivers – and the larger watershed – are looking mighty low.
Eventually, the rivers flow to the ocean, where water evaporation forms clouds and returns water (in a normal year) to the Sierra in the form of snow and rain; that’s the bigger water cycle. But this isn’t a normal year; our winter snow and rain – and fresh water supply – went somewhere else.