The river that drains the capital city of San Salvador is considered to be polluted beyond the capability of most treatment procedures.
This water is considered a biohazard, and the contamination is so severe that it is rendered untreatable by treatment methods such as reverse osmosis.
Cerrón Grande dam was built in 1974 to drive El Salvador's largest hydroelectric project, and the 135 km2 reservoir collects some 3,800 tones of excrement each year from the sewage pipes, as well as factory effluents consisting of heavy metals such as chromium and lead.
[2] Many shallow aquifers are becoming contaminated from the severe surface pollution, and this is critically challenging as deeper wells are more relied upon to provide potable water.
In El Salvador, rivers and streams in the principal agricultural areas are highly polluted by pesticides, particularly by DDT in cotton cultivations in the south-eastern coastal plains.
Concentrations of 3.15 mg of DDT per litre of water have been discovered in the Río Grande de San Miguel.
There are four primary lakes in El Salvador including the Ilopango (72 km2), Guija (44 km2), Coatepeque (24.8 km2), , Olomega ( 24.2 km2) and four reservoirs created by hydroelectric dams discussed in more detail below.
[8] The Cerrón Grande Reservoir, known locally as Lake Suchitlán, is the largest body of fresh water in El Salvador.
Public irrigation projects are also prevalent in other areas where good water and soil are located such as the Lempa River, Titihuapa, Sucio, Torola, Grande, and Suquiapa basins.
[8] Total surface area with irrigation drainage problems was estimated at 370,658 acres (1,500.00 km2) where most of this land is located in coastal plains.
[2] CEL (Comisión Hidroeléctrica del Río Lempa) is a public entity that generates over 90% of the hydroelectric output of El Salvador.
[11] Four projects on the Lempa River constitute all of the hydroelectricity generation in El Salvador and account for 41% of the total electricity produced in the country.
The El Salvador Congress charged the Secretaria Ejecutiva del Medio Ambiente (SEMA) with the responsibility of setting the national environmental regulatory policy and to also enforce its compliance.
[2] The upper watershed of the Lempa River is shared by Guatemala, El Salvador, and Honduras, as outlined in the Trifinio Plan, which was established and signed by the aforementioned countries to address economic and environmental problems in the Lempa River basin, and foster cooperation and regional integration.
The Trifinio plan or treaty sought to provide a more viable and effective alternative to unilateral development thereby concentrating on greater multinational integration.
[22] In 1996, the governments of El Salvador, Honduras, and Guatemala signed an agreement to cooperate on formulating a development plan for their shared boundary region.
The wetlands within the Bahía de Jiquilisco for example are primarily mangrove forests that serve to protect against tidal surges when hurricanes and tropical storms strike.
Without these forests, tidal surges would lead to the salination of fresh groundwater further inland which would contaminate supplies for domestic and agricultural uses.
The objective of this initiative was to increase the capacity of subsistence farmers in the east of the country to better respond to adverse effects of climate conditions, by providing technical assistance to diversify and market crops, reforestation using fruit trees, use of organic fertilizers and small scale irrigation systems.