wiltonh - 7-23-2016 at 09:11 PM
Last year I posted about this new Dam that is being built just North of Cabo. We visited again in 2016 and the Dam is finished and about 1/2 full of
water.
The burning question in my mind was how were they planning to get the water out of the Dam for use by the people as there is no visible out let. A
Mexican in Todos Santos asked me the same question.
After dong some research on the internet and using Google Translate, I found that they plan to fill the Cabo aquifer directly from the stored water
behind the Dam. There is no explanation on how this might work.
Any one have a good idea?
Here is the link to the web page I put up and the last 3 pictures are new.
http://windsurf.mediaforte.com/Baja/Dam.html
[Edited on 7-24-2016 by wiltonh]
dtbushpilot - 7-23-2016 at 09:21 PM
The water is expected to soak naturally into the aquifer. The dams (there are 2 that I know of) are to keep the water from getting away before it can
soak in.
wiltonh - 7-23-2016 at 09:43 PM
This dam is about 150 feet high so there will be a lot of pressure at the bottom.
Here is the Google Translate information about the dam.
As part of comprehensive medium - term actions to control the avenues of extraordinary rains and reduce the population the ravages of drought, the
National Water Commission (Conagua) will shortly begin construction of the dam La Palma, in the municipality of Los Cabos, in Baja California Sur,
reported Israel Camacho Gastelum, Local Director of dependence. the work, which will be financed with federal funds, serve to control the
extraordinary floods generated mainly by cyclones and allow some of that water infiltrates the aquifer Saint Joseph. Thus, groundwater recharges
naturally and in the long run more water is taken into the aquifer. In addition to the reservoir, Conagua will build another in the Municipality of
Comundú, which is in addition to the emergency measures that the Conagua runs in the entity to mitigate the effects of drought, as is the distribution
of drinking water in pipes. La Presa La Palma about 27 kilometers from San José del Cabo, on the river La Palma, a major tributary of the creek will
be located Saint Joseph. You will have the capacity to store, ordinarily, 14.6 billion liters of water, and in extraordinary situations, to 21.9
billion liters of water. Will have a spillway 70 meters and a concrete curtain of 220 meters long and 49.5 meters high. Finally, Camacho Gastelum
announced that, so far, concluded the survey of the 325 hectares that make up the reservoir and reiterated the Federal Government 's commitment to
address timely and effectively the basic water demands of those in water emergency situation.
dtbushpilot - 7-23-2016 at 10:30 PM
Well, there you have it. My guess is that it will work as advertised.
David K - 7-24-2016 at 08:56 AM
Were the 'holes' at the bottom filled permanently or are there gates that can be opened if needed?
Thank you for the great photos!
Osprey - 7-24-2016 at 10:21 AM
I hate to state the obvious but the reservoir will only hold, save and disseminate rain water which falls directly from above it or close enough that
it will be naturally directed toward it. There are hundreds of little catchments all over this desert that have not seen a drop of water except for
the accident of rainstorms that pass right over them.
Put another way: if you had a house out in the desert in southern Baja, would you dig a giant hole near your house and hope for the best?
wiltonh - 7-24-2016 at 10:26 AM
From what we could tell, they were blocked permanently.
It appears that the only outlet is over the spill way.
If you Google Presa La Palma and look at the pictures, it gives you an idea how it would work in a hurricane. There is only one picture of this dam
but some of the others are shown in the over flow mode. It would be very impressive to be there and watch it happen as long as you were not down
stream.
wiltonh - 7-24-2016 at 11:15 AM
Osprey: My first thought was exactly what you stated. That is why we went back one year later to see what had happened.
There was water running through the holes in the dam when we were there the first year so we knew that it might fill some. What we found was that it
was half full. Using the lower number listed from the article above that would be something like 7 to 10 billion liters of water behind the dam. In
rough numbers that is something like 185 million gallons plus. The lake is large enough that we could not see both ends from the road on the mountain
as we came in.
We were totally blown away as to how much water they had collected.
motoged - 7-24-2016 at 11:35 AM
I wonder about the engineering and construction quality looking at the appearance of the ground the dam is built into. A friend in BC worked for BC
Hydro and his only role as a surveyor was travelling around BC measuring how much the nearby mountains that the dams were secured to moved
"regularly"...with varying degrees of measurable movement....
I applaud the need for the dam and all that....just hope it holds up.
AKgringo - 7-24-2016 at 11:52 AM
I fear that in a year that produces several storms like Norbert, and Odile, they are going to wish they had a bigger spillway!
Two years ago, I built a new pond on my property in Northern CA for the same reason. My grandfather had a shallow well that served our needs in the
50's and 60's, but since then, there have been a lot of wells drilled into the fractured shale bedrock that is our aquifer.
My dad built two ponds in the late 60's that have survived even the worst drought years well enough to maintain a healthy fish population.
In between them is a ravine that is right down to bedrock, and had an intermittent spring during the winter months. I did not think it would hold
water all year, but I dammed it up and built a spillway to create about a half acre pond approx 12 feet average depth. It fills up with just one or
two of the sub tropical storms that hit the west coast even in drought years.
It has not gone completely dry (but close) and now, for at least nine months of the year, it is recharging the aquifer with water that would have
washed right through my property in days.
Edit; Even now in late July, there is enough water to be useful for fire fighting efforts.
[Edited on 7-24-2016 by AKgringo]
wiltonh - 7-24-2016 at 11:53 AM
Motoged: If you look at Google Earth, you will see that this dam is built on the up hill side of a sharp "U" shaped bend in the river. I think it
would take a lot of force to move the South end of the dam. The North end is another story. I to hope they have done their homework.
Here is where to look on Google Earth. The picture is old as it shows no water behind the dam.
Latitude: 23.253633°
Longitude: -109.826092°
[Edited on 7-24-2016 by wiltonh]
vandenberg - 7-24-2016 at 11:57 AM
A good tropical storm could fill this lake up in short order. And then the great pressure of the volume of water should penetrate the ground to the
aquifer at a much faster rate than just rainfall.
Osprey - 7-24-2016 at 11:58 AM
The engineers know that Baja Sur (hurricanes or no) gets an average of 7 inches of water from rain per year. They also know the evaporation is rate is
about 110 inches per year. What they probably don't know is the recharge rate of the aquifers they hope to fill or if some of them are sealed like
many in the Viscaino desert (Constitución).
Our little dam at Boca de la Sierra fills up with silt but good years and bad sends the water to the right place; the village and fields below are fed
by a one kilometer concrete aqueduct that finds it's way to the fields without following the canyon, the arroyo. Clever dudes.
[Edited on 7-24-2016 by Osprey]
wiltonh - 7-24-2016 at 01:35 PM
If you do some internet searches for La Paz and Cabo water, you will end up with people discussing how everything is limited by the amount of water
that is available. Much of it is pointed at the mining industry because towns El Triumfo have found arsenic in their water supply. It is left over
from old mining in the mountains and it gets washed down when it rains.
The more surprising thing is there is almost no mention of this dam and the positive things it may bring to BCS. Maybe more tourists is not
positive but rationing water to the locals to support tourism sure is a negative, which I hope ends.
I guess the internet is in no way fair or balanced but companies like Conagua could help spread the word about what they are doing to fix some of the
problems.
Bajahowodd - 7-24-2016 at 03:48 PM
I am puzzled by this project. As a long time visitor and a part time resident of the area, first of all, for any years, new resort development has
been ordered to install desal facilities. So, this is not about drinking water. Second, even with the most horrible hurricanes, both CSL and San Jose
have survived and recovered.
I can only think of this project as pork barrel, unless anyone else can convince me differently.
wiltonh - 7-24-2016 at 04:25 PM
The articles I read suggest that the main aquifer under Cabo is being pumped at a rate that cannot be sustained. Most aquifers in Baja have fresh
water that is sitting on top of salt water. Once they pump to a certain level the salt water comes in and ruins the aquifer for ever.
The goal is to replenish the aquifer before this happens. By damming up a river, the water forms a lake and hopefully starts to replenish the
aquifer.
The natural streams dump their water into the ocean or the sandy desert before it can fill the aquifer.
I would like to see the data on how much water actually makes it into the aquifer and is then pumped out for use when compared to just putting in a
pipe and using the water to fill the local tanks directly.
After looking at some of the pictures on the internet of other Mexican dams, I see that there is a hole near one end where a pipe can be connected.
This dam has that hole on the Southern end but no pipe.