Water Resources in Managua
2.2 Water Resources in Managua
Within the national territory, particularly in Managua, there is high potential for both surface and groundwater resources. They include the Asososca Lagoon (Figure 2.1) and the Managua aquifer (Figure 2.2), which currently serve as supply sources.
Another body of surface water is Lake Xolotlán, Figure 2.2 The Managua Aquifer
the second largest lake in the country, which is embedded, for the most part, in a formation of volcanic materials and occupies part of the Nicaraguan graben (rift valley) (ENACAL, INETER, CIRA/UNAN, 2008). Although the capital is built on the shores of Lake Managua and could, as it did prior to 1930, have an abundant water supply from Lake Xolotlán, its contamination makes it unsuitable to directly benefit the populations living along its shores. The lagoons of Nejapa, Tiscapa, and Acahualinca, which occupy the bottoms of old volcanic craters formed by explosion and sinking approximately 5,000 years ago, are also located in the urban zone.
Of the two watersheds for the municipality of Managua, the north and south watersheds, the south watershed (825 km 2 ) drains its waters into Lake Managua or Lake Xolotlán. It is divided into four sub-watersheds with three pertaining to Managua that occupy approximately 70% of the municipality
Source: Proyecto Uno Sostenible de los Recursos Hidricos (SUWaR)
URBAN WATER IN NICARAGUA 419
The southern watershed of Lake Xolotlán, due to inadequate management of agriculture, solid waste, geo-morphological, environmental and particular
sewage and rainwater, which causes environmental urban development characteristics, is vulnerable to
and socioeconomic devastation. In the high part, natural phenomena related to climate, volcanoes,
agriculture has contributed to rapid deforestation and earthquakes. This part of the watershed does
(Figure 2.3), especially in areas with steep to moderate not have significant watercourses; there are only
slopes (the Mayor’s Office of Managua, 2008). seasonal ephemeral and some permanent streams
In the last several years, the medium and low with a short course and low volume (the Santa Elena,
part of sub-watershed III has gained importance Borbollón, and Lodoso Rivers). The topography of the
as a residential area. This is especially due to the southern watershed and replacement of the original
development of the highway to Masaya and the vegetation by dispersed annual crops have made
neighboring areas. The growth of urban develop- it possible for erosion to form gullies and ravines,
ments and changes in land use imply an increase especially in the piedmont areas (200-450 meters
in surface runoff, more erosion, and more demand above sea level) (INIFOM, 2013).
for infrastructure in the drainage and basic service network (the Mayor’s Office of Managua, 2008).
2.2.1 Surface Water Resources in Managua
The more outstanding surface water resources
South Watershed for Lake Xolotlán
are the waterbodies in craters:
Of the 4 sub-watersheds into which the southern watershed of Lake Xolotlán is divided, the sub-wa-
The Lagoon of Asososca
from Nahuatl for Blue Waters, is a natural water from the coasts of Lake Managua (40 meters above
tershed III covers a territory of 178 km 2 and extends
reservoir and the only waterbody that the city has sea level) to the El Crucero Plateau (940 meters
with quality suitable for human consumption. The above sea level).
fact that it supplies between 14% and 20% of the Sub-watershed III is the most important demand for the population makes it a major source. recharge area for the aquifer that supplies potable
It began to be exploited for potable water in 1914 and water to Managua. It contains three fields of wells
has been part of the water supply system since the that produce 60% of the water supply for the city of
wells that were dug around Lake Managua were Managua. Sub-watershed III is also an invaluable
abandoned (ENACAL-PNUD-OPS, 2006). area for biodiversity and rich soil quality for
Current Condition. Progressive deforestation production. However, it is a highly vulnerable zone
of the southern watershed for Lake Managua has due to the uncontrolled growth of the city and the
decreased infiltration and caused a drop in the water table on the subjacent plains with the consequent drop in the level of the lagoon, which reached critical
Figure 2.3 Agriculture (Pineapple Crops) in Ticuantepe, limits at the beginning of the 90s. This body of water Aquifer Mantle
is well preserved due to the fact that it is protected as
a water supply source for the city of Managua. The activities around the protected area include commerce, oil refining, sand extraction, and residential deliveries.
Main Threat. The study titled “Industrial Contamination of a Municipal Water Supply Lake by Induced Reversal of Ground-Water Flow, Managua, Nicaragua,” carried out in 1991-1992, found that a possibility exists that when more water is extracted than the recovery capacity for the Lagoon of Asososca, an inversion of the gradient may occur causing contamination from the waters of Lake Managua. Likewise, evidence was found of
420 URBAN WATER CHALLENGES IN THE AMERICAS
Figure 2.4 The Refinery on the North Bank of the the relative mobility of synthetic organic chemical Asososca Lagoon
compounds coming from the industrial area (Figure
2.4) (Bethune, Farvolden, Ryan & López, 1996). The possibility also exists of contamination of the underground currents that cross the city and supply water to the lagoon due to the presence of fuel service stations (Figure 2.8).
The Lagoon of Tiscapa
From Nahuatl Uticapa Techcath, the sacrificial stone, the smallest of the crater lagoons (Figure 2.5, Table 2.2), was declared to be a Natural Reserve in 1991 by Decree 4291 (The Mayor’s Office of the Municipality
Source: El Nuevo Diario. 2011.
of Managua, 2004).
Current condition. Until several decades ago, this waterbody was recommended as a potential Figure 2.5 Lagoon of Tiscapa, Receptor Waterbody for
source for human consumption for Managua (the Rainwater and Domestic Waste Water since 1980
United Nations, 1976; Sawyer H. A., 1973). Studies carried out from 1989 by the Nicaraguan Research Center for Water Resources of the National Autono- mous University of Nicaragua (CIRA/UNAN) to date have revealed a progressive, generalized deteriora- tion in the environmental status and the quality of its waters. Evidenc for these conditions are provided by the drastic decline in dissolved oxygen begin- ning at 2 meters, a high concentration of nutrients and phytoplankton biomass dominated by cyano- phytes that is associated with its hypereutrophic status, as well as a high content of microbiological contamination indicators (thermal tolerant Coli- forms, Escherichia coli and fecal streptococci). Cur- rently its waters are severely restricted for any type
Figure 2.6 Lagoon of Tiscapa
of use (CIRA/UNAN, 2008).
The inappropriate management of its micro-wa- tershed (Micro-watershed D) and the erroneous in- stitutional decisions led to the contamination with an accumulation of solid waste in its waters and on its shores (Figure 2.6), as well as the excess of nutri- ents and large quantities of sediments around the discharge canal, all damaging the terrestrial and aquatic ecological diversity (The Mayor’s Office of the Municipality of Managua, 2004). Information supplied in June 2000 by the cleaning coordinator of the Municipality (David Castillo) indicates that the
Source: El Nuevo Diario. 2011.
lagoon receives two metric tons of organic wastes per week (La Prensa, 2013).
Lake Xolotlán or Lake Managua
Is the second largest lake in Nicaragua based on
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its dimensions (Table 2.1); the volume of stored reestablished sporadically in the years of the large water is around 1010m 3 . In 1910, the connection of
hurricanes and extraordinary water discharge this waterbody through the Tipitapa River to Lake
events, when the level of its waters exceeds 39.22 Cocibolca or Lake Nicaragua (Figure 2.7), which has
msnm (Paso Panaloya) (INETER, 2014). This occurred the largest dimensions and is located some 9 meters
during the last century in 1993, 1954, 1982, and 1998. lower (Plata, Araguás, Avilés & Peña, 2001), was
But recently the two lakes have been connected interrupted. Since then, the connection has been
constantly since October of 2010.
Figure 2.7 Lake Xolotlán or Lake Managua
Source: El Nuevo Diario. 2011.
422 URBAN WATER CHALLENGES IN THE AMERICAS
Current condition. Lake Xolotlán is a body of water that has been contaminated naturally by the volcanic activity from the immediate surrounding areas (hot springs enriched by boron and other met- als) and externally by the increase in human activi- ty in the surrounding watershed (Meulemans, 1991).
Managua, which is located on the southern bank of the lake (Figure 2.7), has used this waterbody as a recipient of its waste waters (industrial, domestic, and rainwater) without any sort of treatment from 1927 (Vammen & Hurtado, Climate Change and Water Resources in Nicaragua, 2010) to 2009, when a water treatment plant began operations. In addition to wastewater, leachates also have contributed to contamination of its waters since 1972 from solid wastes from La Chureca municipal dump (47 hectares in area) located directly on the banks of the lake (CIRA/UNAN, 2010). There was no environmental management applied to the wastes until it was sealed in 2010. Currently, the site has the most modern treatment plant in Latin America which is part of the Integral Development Project for the Acahualinca-La Chureca neighborhood in Managua. It was installed six years ago by the Spanish Cooperation in Nicaragua and now recycles at least 1,000 tons of waste daily. A breakwater wall was also built there to protect Lake Xolotlán which has an extension of 1,745 meters.
One of the worst source of contamination for the lake was the Hercasa-Elpes complex (Pennwalt) which produced sodium hypochlorite and chlorine gas. Their wastewater had a high mercury content which was released to the lake from 1967 until 1992., This factory set up operations, like many other industries, in the southern coastal strip of the lake in order to easily dump its wastes into the ecosystem. It is estimated that it released 40 tons of elemental mercury into Lake Xolotlán. Very high levels of mercury were found in the different ecosystem compartments, according to the study done by CIRA/UNAN en 1991 (Lacayo, Cruz, Lacayo & Fomsgaard, 1991). Some results of the project titled “Environmental Contamination by Mercury in Lake Xolotlán, Nicaragua: An Evaluation of the Risk to Human Health,” currently being executed by the Nicaraguan Research Center for Water Resources in cooperation with the National Institute of Minamata Disease from Japan, have confirmed that
the area surrounding the old factory facilities (soil and groundwater) is contaminated. It constitutes a potential source of mercury for Lake Xolotlán (Peña, Montenegro, Pitty, Matsuyama & Yasuda, 2007).
Both the northern and southern sectors of the watershed have undergone deforestation and this is a major source of nutrients and suspended solids in the lake due to erosion as well as other human activities that have been improperly managed (ENACAL, INETER, CIRA/UNAN, 2008; CIRA/UNAN- CARE-MARENA/PIMCHAS, 2012). In general, the waters of Lake Xololtán are not suitable for human consumption. There are also heavy restrictions on irrigation due to the high concentrations of sodium, chlorides, and boron, as well as the danger of salinization and alkalinization of the soils (ENACAL, INETER, CIRA/UNAN, 2008).
2.2.2 Groundwater Resources in Managua
The Managua aquifer, located south of Lake Xolotlán, oscillates between 6 and 150 meters in depth (ENACAL, 2008) and has an approximate area
of 600 km 2 . Numerous activities are carried out in its area that are potential sources of contamination such as industry, agriculture, municipalities, and fuel service stations, etc.
Table 2.1 Characteristics of the Main Surface Water Resources in the City of Managua
Body of Water
Form and Surface Depth
Lagoon of Asososca 1
37.69 meters above
Circular form Area: 0.8 km 2 Diameter: 1.2 km
Maximum: 95 m
Lagoon of Tiscapa 2,3
51.79 meters above
Area: 0.16 km 2 Diameter: 500 m Practically vertical
Maximum: 33 m Median: 20 m
Lake Xolotlán 4,5
37.84 meters above
Area: 1,052.9 km 2 Maximum Length:
58.4 km Maximum Width:
Maximum: 26 m Median: 7.8 m
Source: Ministry of Finance, 2014
1. MARENA - PROTIERRA - CBA; 2. The Mayor’s Office of the Munici- pality of Managua, 2004; 3. CIRA/UNAN, 2008; 4. ENACAL, INETER, CIRA/UNAN, 2008, 5. INETER-OIEA, 2001
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Knowing the aquifer’s water potential has Figure 2.8 Underground Environs for the Asososca Lagoon been the object of much concern and, therefore was the objective of several studies carried out in the last several decades. In 1993, the Nicaraguan Water and Sewer Institute (INAA in Spanish) and the Japanese International Aid Agency (JICA), using a modeling program for groundwater, found indications of overexploitation and the threat of contamination in the central sector. Therefore, they recommended reducing the pumping rate and developing new sources based on the increase in the
demand that was determined for 2000 (553,000 m 3 /
day). Later, (Cruz, 1997) determined that, with the level of extraction in 1996 from the aquifer, it was not overexploited and that it did have the capacity to cover the demand for 2010.
The groundwater produced by this watershed is the main means of supply for a large part of the capital city. There are five major fields of wells whose extraction volume represents more than 50% of the well production of the Nicaraguan Water and Sewage Company for all of the Managua aquifer (SUWaR-Nicaragua, 2000). In general, the water quality is suitable for human consumption; it has been classified geochemically as mostly carbonated- bicarbonated with a pH between 7.2 and 8.2.