AJIJIC VILLAGE HOMES    

Lake Chapala ends hydro-year with record high

This year has seen the greatest recuperation since 1958

as reported by Dale Hoyt Palfrey (Guadalajara Reporter, November 8-14, 2003)

For Lake Chapala the year 2003 is sure to go down into the history books. On October 31, the official closing date of the 2002-2003 hydrological cycle in the Lerma-Chapala Basin, the lake contained 4,124,393,000 cubic meters of water, equivalent to 52.25 percent of full capacity. One year ago the lake held less than half that amount, ending the cycle at 23.24 percent of capacity.

Between June and October of this year, Chapala gained a total of 2,817 million cubic meters (Mm3) in volume and ascended 3.11 meters in level, continuing on the rise this week at a rate of approximately one centimeter per day. By contrast, during the 2002 rainy season the lake recuperated only 781,00 Mm3 in volume and 1.01 meters in level.

Until last year Mexico's largest lake had been on a steady decline for a full decade. Volume in excess of 4,000 Mm3 had not been registered since 1996. Last year's modest improvement over previous years was attributed to the transfer of water reserves from dams located in the upper Lerma-Chapala Basin. This year's bonanza has been the result of the prodigious volume and timing of rains that lashed central Mexico over the past three months.

A look at Chapala's history shows that a total annual rise of more than three meters is a meteorological oddity occurring on the average of once per decade. The most recent recuperation of any consequence was a 2.55 meter gain in 1991. The all-time record breaker was 1958 when the lake ascended a phenomenal 5.02 meters in a single season.

The 11 major dams in the Lerma-Chapala Basin closed the 2002-2003 cycle with reserves of 2,306 Mm3, as opposed to 1,711 Mm3 last year. All but one now stand at volumes above what the National Water Commission (CNA) considers to be full capacity. The Lerma River's Solis Dam, the largest of the lot, registered in at 870 Mm3, equal to 119 percent of its capacity as of October 31.

With the rainy season now trickling off, the on-going venting of the dams accounts for most of the continuing in-flow to Chapala.

How much more water is to be destined for the lake is likely to be a hot-button topic at the annual meeting of the Lerma-Chapala Basin Council technical committee set for November 14 when the CNA announces distribution volumes to be allocated for the coming year. It will be the first time since 1997 that the lake has ended the rainy season above the critical mark of 3,300 Mm3, bringing to bear a different mathematical formula for dividing water resources among the authorized users, than those employed in recent years.

Lake Chapala's ups & downs

Although Lake Chapala has always fluctuated in volume between Mexico's dry and wet seasons, critical lows registered in recent years appeared to threaten its viability. Could the phenomenal recuperation of 2003 mark the natural turn-around a few optimistic lake-watchers have long predicted?

Here's a look at the highs and lows of Chapala's water volume over the past ten years.*

 * Figures are expressed in millions of cubic meters, i.e., 5,598 Mm3 is equal to 5,598,000,000 cubic meters.