Aug 30, 2006, 9:18 AM
Post #8 of 18
You raise a number of good questions. Some of them can be easily answered .
There are no plans for any major new dam upstream of Lake Chapala. There are plans for a dam on the River Santiago downstream of the lake, to provide additional water for Guadalajara, and reduce its dependence on Lake Chapala.
The agricultural problem is two-fold. Pumping waste into the Lerma (such "waste" is now treated, prior to entering the river) and the additional of agricultural run-off (containing fertilizers and pesticides) do raise issues about water quality. Probably of greater concern is the volume of water being used for agricultural activities within the basin. Even a relatively small improvement in agricultural water efficiency (such as by using drip rather than flood irrigation) would have a tremendous effect on overall water budget figures for the basin.
I do not for one second believe there is any evidence that any slow-acting fertilizer was added to the lake earlier this year. A herbicide was added, however, in order to reduce the lirio. The use of herbicide in this context appears to still have the support of eminent lake scientists such as Dr. Manuel Guzman of the U. de G. Institute of Limnology, despite the change of heart of Amigos del Lago (which was a supporter of heribicde use ten years ago). It appears that herbicide use, whatever its drawbacks may be, is the only effective (costs, labor and time) short-term solution to the lirio. It has been well documented that recent (last 70 years) lirio "attacks" coincide with rising water levels following extended dry periods.
Even the number of underwater springs, let alone their flow volumes, are largely unstudied. The above-mentioned Dr. Guzman published a relatively recent account of the state of knowledge of these springs a couple of years ago. I am very interested to know who is proposing dredging the springs as a means of increasing their flow. This is not an idea I have heard previously, and I thank you for bringing it to my attention.
(This post was edited by tonyburton on Aug 30, 2006, 9:44 AM)