From Watershed to the Faucet: The Path of Salt Lake City Drinking Water
When we turn on our faucets at home we expect water to come rushing out of them on demand. It’s easy not to think about where that water comes from or how it’s treated. But with climate change and persistent droughts across the West, many city water managers have to find creative ways to supply growing populations with the water they need. We continue our series, Utah’s Uncertain Water Future, with a look at the sophisticated system that brings clean drinking water to the residents of Salt Lake City.
City Creek, Parleys, Big and Little Cottonwood Canyons are the water sheds Salt Lake City depends on for drinking water. Laura Briefer is the water resources manager for the city. She says our population is extremely fortunate to have such access to such clean sources.
“A drop of water would come down Big Cottonwood Stream, go into our water treatment plant at the mouth of Big Cottonwood Canyon , into our water distribution system and then ultimately to our taps in the Salt Lake Valley. It takes about 24 hours for that drop to make that journey,” says Briefer.
Just last month, city water mangers took the Big Cottonwood Canyon water treatment plan off line to make some improvements. A brand new water intake structure was built as a first line of defense against unwanted particles. Bill Meyer is a water treatment plant manager for Salt Lake City.
“We try to remove as much of the debris before it goes into the facility and then of course the treatment process starts there. The old one like I said only could remove the sands and rocks and so on and so forth. The way this one is designed is that it will remove all of the vegetation as well because of the one millimeter screens we’re putting in. So we will only get basically water coming into the facility,” says Meyer.
The filtration process continues inside the building and then the water is chemically treated.
“We do generate our own chlorine here on site so it’s a weak solution, it’s very safe to use and of course it keeps us from smelling like chlorine all the time – like a pool in here which is nice. Once that’s done we add ferric, which is right here and then we flash mix it. These big mixers in here stir this up very rapidly to bring all of that together,” says Meyer.
Meyer says the ferric has a positive charge that helps pull microscopic solids out of the water. A small amount of lime is added for PH adjustment. Workers also insert fluoride at the end of the process. All of the valves in the filter building were recently refurbished or replaced. Meyer says that improvement will dramatically increase efficiency in the filtration process.
“Well, we were losing a lot of water. It turns out to be about 250,000 dollars worth of chemical and electrical costs it was charging us on just water loss returned back to the facility because we don’t really lose our water, we just have to retreat it. So we decided to stop that by replacing and refurbishing all of the valves in this filter building,” says Meyer.
Once the treated water leaves the plant, it’s channeled into the city’s vast pipe infrastructure and eventually makes it way to the taps of Salt Lake residents. But not every city in the U.S. has the ample surface water resources of the Wasatch Front. Severe drought in south and west have forced municipalities to find unorthodox ways to meet drinking water demand. The city of Wichita Falls in north Texas recently found itself in a crippling drought that was drying up the two lakes it depends on for its drinking water.
“By the end of 2011 we were nearing fifty percent in our combined capacity. Over the next few years up to date, we’ve actually dropped from fifty percent down to the low twenties,” said Mark Southard, Water Purification Manager for Wichita Falls.
With his city facing a serious crisis, Southard and other water mangers implemented a program that now recycles human waste water and blends it with lake water to produce the city’s drinking water supply. Southard says public reaction has been mostly positive.
“We’ve heard a lot of comments from people that say they actually think the water tastes better with fifty percent reverse osmosis blended with fifty percent raw lake water. So, we’ve had some very positive comments even after the water’s gone out to the public,” says Southard.
Waste water recycling is a strategy more cities are willing to consider as surface water sources shrink. It’s not a choice that Salt Lake City currently has to consider, but a dry winter and lean snowpack have forced city officials to acknowledge that we are facing a drought. The city issued a stage one water advisory recently asking to residents to practice conservation. But Laura Briefer says that for now enough water is stored to meet the challenge.
“We have participated in the development of the Deer Creek and the Jordanelle system in the Provo River drainage and right now the capacity of that reservoir system is about ninety seven percent. Last year we really managed our sources of water to carry over some of that storage capacity in case we had a drought this year,” says Briefer.
Briefer says climate change will be the factor that has greatest influence on how many cities develop strategies to face water challenges. That means that even though we still get water on demand, we need to start paying more attention to how much we use and stop taking this precious resource for granted.