I was wondering if there is water available at Lee's Ferry to fill up our
5 gallon jugs. If so, does it taste good, or is it better to fill up somewhere else?
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There has always been water at Lees Ferry although I'm 18 months out of date. Tasted fine to me last time I was there.
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Actually if the river is running clear, I would just pull from the river and lightly chlorinate rather than carry the 40 pound loads back to the boat ramp. That's what we do on the river all the time so we just start a bit quicker.
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The Ferry water always tasted OK to me. I've always run a truck or trailer up to the faucet with lots of our containers, filled them, then drove back down the ramp to drop them at the beach for loading onto boats.
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Re: Norwalk Virus Investigation Report and UV versus chlorine question.
Well, now you have my curiosity going so I wasted a few minutes (OK 45 minutes) when I should have been completing my work to look up chlorine resistance and Norwalk virus.
The most interesting thing I had never considered in detail was the
difference between antibiotic dosing and sanitizer/disinfectant dosing.
Bacterial resistance to antibiotics is quite well known and well-documented. I assumed (like many of you) that sanitizer or disinfectant dosing is similar; therefore, the mechanism of mutation to become resistant must be the same, right? Wrong. What came to my mind was that, unlike antibiotics, chlorine (at least) chemically oxidizes the organism, a reaction which the organism has no opportunity to develop resistance. (Antibiotics utilize some facet of the organisms life cycle to inactivate the organism, which allows the organism the opportunity to mutate one gene function and become resistant. Also, antibiotics are dosed at much lower concentrations than disinfectants because they are used with living creatures unlike disinfectants which are applied to inanimate surfaces most of the time. This provides greater likelihood that some fraction of the organism population may survive the antibiotic treatment process). Hence, the reason I got interested in the comments regarding chlorine disinfectants seeming to be less effective than UV.
Here's the information as I understand it. A number of biological pathogens (remember Giardia and crytosporidium) have a life stage that resists chlorination. The reason these organisms survive is because they form a cyst or oocyst that has an outer membrane which is too tough for the chlorine to oxidize at the levels supplied for disinfection purposes. So, the way to eliminate the cysts is to filter them out, which requires a filter with a small pore diameter (0.5 microns) to capture the cysts effectively. Viruses, however, are much smaller in diameter and no filter on the market has an effective pore diameter small enough to eliminate viruses.
So, we are instructed to also use a disinfectant, and one of the most
commonly used disinfectants is chlorine, usually supplied as sodium
hypochlorite solution (household bleach is 5% by weight sodium
hypochlorite). The actual oxidizing agent is free chlorine, which is
liberated in solution by changes in the pH. In other words, you can look up the concentration of free chlorine in hypochlorite solutions at given pH's and have an idea of the concentration in parts per million of actual free chlorine. Hypochlorite is also an oxidizer but it is not nearly as potent an oxidizer. The problem with chlorine is that it is a non-specific oxidizer, which means that any organic matter in the water is oxidized by the chlorine and represents a "demand" on the available chlorine. So, if 10 ppm of chlorine is required to kill the norwalk virus and the water is turbid or otherwise contains a higher than desirable organic load, the chlorine will be consumed oxidizing the virus and any organic matter. Once the chlorine is used up, if any virus remains, it will still be viable to cause unpleasantness.
UV is also a strong oxidizer and is also negatively effected by the presence of impurities in the treated water.
I suspect the difference in effectiveness of chlorinated water users and UV users has to do with the degree of control exercised by the chlorine users. On the UV systems, there is no adjustment (I assume) with regard to the power supplied to the UV sources and little or no adjustment to the flow rate of water through the UV system. The effectiveness of the UV treatment is a function of the strength of the UV source, the rate at which the water passes by the UV source, and the effectiveness of the UV light passing through the water. In other words, the user has little to adjust and, in all likelihood, the systems are set up to "overtreat" in 99+ % of the situations. So, disinfection of the water is pretty well assured.
Chlorine dosing, on the other hand, is an individual art. He who doses the water in the gerry can dictates the level of treatment each time the water is dosed. And, the amount of turbidity remaining in the water effects the treatment as well. So, I suspect that the difference is adding a little more bleach on some trips and a little less on others.
I would reiterate my concern about UV systems, that the user must
absolutely protect the treated water from accidental contamination once treatment is complete because no residual disinfection characteristics are supplied. With proper chlorination (which is both time of contact and concentration of contact), enough residual should be left to protect the users from some moderate level of contamination after treatment.
This reinforces my thought that the person that chlorinates the water on trips needs to be very conscientious about the application of chlorine. Too much and people will avoid drinking the treated water because of taste and too little and people will avoid drinking the treated water because they are puking.
Another thing I came across was that the infection person to person is thought more often to be from airborne viruses following an episode of "projectile" vomiting. So, the people on a trip may be
absolutely strict in the hand washing, etc., and still pass on the
virus because someone becomes infected and puked, passing the virus on by inhalation, rather than ingestion.
Also, the Norwalk virus is extremely common, according to the CDC. An on-going outbreak suggests a continuing source, like the waste water treatment plant, but it could also be something like a raw food supplier (Does everyone use the same supplier of bulk produce for example), or some other, out of the river corridor, source.
Ah well, enough pondering.