Río Lerma

	Río Grande de Santiago
River system	Río Grande de Santiago
source	Lake Chapala ; 20 ° 19 ′ 2 ″ N , 102 ° 47 ′ 29 ″ W.
Source height	1510 m
muzzle	at San Blas in the Pacific ; 21 ° 37 ′ 55 ″ N , 105 ° 26 ′ 46 ″ W
Mouth height	0 m
Height difference	1510 m
Bottom slope	2.7 ‰
length	562 km
Reservoirs flowed through	Aguamilpa dam , El Cajón dam , La Yesca dam

	Río Lerma
	Rivers of Mexico
	Data
location	Mexico
River system	Río Grande de Santiago
Source height	2600 m
muzzle	Lake Chapala coordinates: 20 ° 12 '26 " N , 102 ° 46' 21" W 20 ° 12 '26 " N , 102 ° 46' 21" W.;
Mouth height	1510 m
Height difference	1090 m
Bottom slope	1.5 ‰
length	708 km
	Bridge over the Río Lerma

Waterfall at La Piedad de Cabadas

The Río Lerma Santiago is with approx. 708 km Mexico's second longest river after the Río Bravo del Norte . Most of the time, the two sections Río Lerma and Río Grande de Santiago are viewed separately.

course

The Río Lerma (formerly also called Chicnahuapan ) rises south of the Nevado de Toluca about 24 km southeast of the city of Toluca in the state of México and then flows mainly in a north-westerly direction. It forms the political border between the states of Querétaro and Michoacán and flows through Guanajuato . After about 700 km it flows into Lake Chapala , from where it flows under the name Río Grande de Santiago and flows into the Pacific Ocean 16 km north of San Blas in the state of Nayarit .

The catchment area up to the confluence with Lake Chapala is the Lerma-Chapala Basin .

Usage and pollution

The non-navigable Río Lerma forms a main water reservoir for the capital Mexico City and its surroundings. The river suffers from intensive use as a fuel and through the industrial belt of the Bajio. It is dammed in Nayarit by the Aguamilpa dam and the El Cajón dam .

The water quality was severely impaired by industrial and human wastewater (aguas negras) , but has improved somewhat in recent years due to the construction of sewage treatment plants . However, several previously very popular edible fish have become extinct.