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Aug 27, 2007, 8:47 PM

Post #1 of 5 (1625 views)


Rio Lerma

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We were watching the TV news here in Cuernavaca tonight. They showed footage of the Rio Lerma, which is flooding with a lot of runoff. Maybe the pond will become a lake again.

That will be a good thing for us here, too. We won’t need to keep reminding people to be sure to flush the toilet, because Chapala needs the water.

"The supreme happiness of life is the conviction that we are loved" - Victor Hugo


Aug 28, 2007, 8:25 AM

Post #2 of 5 (1588 views)


Re: [RexC] Rio Lerma

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Checking out the edge of the lake at the Ajijic pier Sunday really depressed me. While the lake is definitely rising, the water looks like it has been tainted by the most disgusting crud in the world. It is definitely more polluted than before the beginning of the rainy season.

The constant runoff from the denuded areas where new construction is going full bore and Rex's sewage and all the other crud from upstream make it quite unappealing.


Aug 28, 2007, 8:54 AM

Post #3 of 5 (1586 views)


Re: [dlyman6500] Rio Lerma

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I sure hope it's only mud that will precipitate to the bottom with time, but I think I know better. So what happens after another 100 years? Does the lake fill up with all this precipitation from the runoff? Maybe it's good I wont be around to find out.


Aug 29, 2007, 8:02 AM

Post #4 of 5 (1547 views)


Re: [johanson] Rio Lerma

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   I am a very active volunteer with Amigos del Lago de Chapala (Friends of Lake Chapala), a non-governmental organization founded
to help protect Lake Chapala and the watershed (see I have prepared this response to the preceding exchange
of thoughts about the lake with the help of one of our consultants.
There is no question that turns of nature, as well as politicians' decisions, can lead to higher lake levels. The Rio Lerma
flooding is a mixed blessing of added water to Lake Chapala along with the disadvantage of added sediment. Because of the very
shallow nature of the lake, it must be accepted that the area within 100-300 feet of the shore will always be murky and even downright
muddy-looking since it takes only a one-foot high wave to constantly churn up the muddy bottom. Only looking further out into the lake
or adding a sandy bottom along the shore will result in clearer water.
Amigos del Lago board members are very intent this year to uncover and/or create water test data to show the public what contaminants
exist in the lake, where, and at what levels. The existing information
has been very difficult to get ahold of as it seems to be considered proprietary by whoevever collects it. But we persist, assembling
pieces of data from a variety of sources. At present, for instance, there is a team of research professionals working to pull
together published data about the lake and summarizing it into a readable format.
As to human health and recreational use of the lake, our "experts" are most concerned about slightly elevated E-coli values
near those towns without (or with malfunctioning) wastewater treatment plants. Once one is out 300 ft from the shore, the
scientists we've talked to tend to believe that all criteria for safe recreational use are met. Thus, we are anxious to soon
have the government release its test data (efforts continue on the part of Amigos del Lago and its partners to try to get such
information using Mexico's Law of Transparency), and we are continuing to seek means to fund the testing of the water at key
locations along the lake shore.


Sep 11, 2007, 1:11 AM

Post #5 of 5 (1468 views)


Re: [ecollard] Rio Lerma

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Just a couple of thoughts to add to your excellent summary, Eileen: First, if left alone, nature can do an amazing job in a short time of restoring what humans have messed up for decades. There's a large lake just west of Minneapolis, Minnesota that had suffered mightily from municipal sewage inflows, farm and lakeshore home septic system and fertilizer runoff, as well as other pollutants. After installing area-wide trunk sewer lines & service to homes (diverting the black water to a remote regional treatment facility) - building catch basins & settling ponds - discouraging excessive lawn fertilizer use by waterfront home owners - and banning the further removal of marshes at the lakes' edges, it took less than 5 years for noticeable improvement in water clarity and elimination of algae blooms, and another 5 for the lake to look as good as it did in the 1940's. BUT what nature was not able to do was remove the pollutants that had been "washed" out of the water by rain & gravity and into the lake bottom. Any agitation of that sediment in shallow areas released the pollutants (which were "locked" in the lake bottom) back into the water. So your comment about the shoreline is well taken. There can be anoher source of agitation than normal wave action, however: powerboats running at high speed. One solution is to post "no wake" zones in shallow areas(including near the shore) (which require policing), another is to restrict water use to canoes, sailboats, small fishing boats and/or boats with small electric motors only.

While running water analysis tests can produce important information, a cheap (but labor-intensive) way to monitor water clarity is via the use of setchi (sp? - pronounced "set-chee") disks. These are simple and easy to make: take a (roughly) pie pan-sized disk, divide it into quarters, and paint each alternate section black and white. attach a line with depth markers along its' length, and add a weight on the bottom, if needed. The disc is lowered into the water and the depth at which the black & white disc disappears from view is noted. This could be done at the end of a pier, or by boat (which may require use of a GPS). Periodic readings over time will give a measurement of improvment or lessening water clarity. Another lake with the desired water clarity could be checked with the disk for comparison purposes.

The $64,000 question is: who would do the secci-disk work? In Minneapolis, public employees. At Lake Chapala, I suspect it would have to be volunteers, or, if it could be made part of an ongoing school program with adequate supervision & control(s), perhaps students. Like the wonderful Ajijic Limpio program, it could raise environmental awareness and serve an educational purpose.

BTW, if anyone runs across a depth chart of Chapala Laguna, no matter how old, I'd love to have a copy of it...8^). Buena suerte al Amigos del Lago.
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