A watershed encompasses all the territory drained by a river and its tributaries, from its point of origin to its drainage point. Consequently it would be absurd to think that the country only has three main watersheds.
Besides the actual length of a river, it is also important to take into account
how much water it carries. Common sense dictates that the larger the watershed, the
larger the amount of water that will be carried since the likelihood of tributaries
is then higher. Precipitation will, naturally, also play a significant role in the
amount of water carried, as will the type of soil that forms the riverbed.
Characteristics of Waterflow
The course of a river is determined by the topography around it and the type of rocks
over which it circulates (e.g. limestone will present less resistance to water flow
than granite so that the river’s course would likely be straighter through limestone).
Surely, anyone who has ever seen a map will have noticed that no river travels in a
straight line. This is because the gravitational pull of the earth causes water to run
in a wavy pattern. This is a type of manifestation of the coreolis effect. The pressure
points created by this pattern are responsible, in part, for the sinuous nature of the
riverbanks. The direction that a river takes, consequently, will be determined by the
tract that it manages to carve as it seeks the lowest lying areas until it eventually
meets its drainage point.
The force of the current is also a function of the topography. The rivers descending
from Dipilto, for instance, drop more than fourteen hundred metres in less than thirty
kilometres, while the San Juan, flowing through a valley, descends barely thirty metres
in its one hundred and ninety kilometre run.
Watersheds
Following we will take a brief look at some of the most
important watersheds in the country. The importance of a watershed,
for our purposes, may stem from either the size of the territory drained, its economic
potential,its historical value, or its ecological characteristics.
Gulf of Fonseca Watershed
The two longest rivers of the Pacific Region drain in the Gulf of Fonseca: Negro and
Estero Real. The Negro originates and drains in Honduras, but most of its course runs
through Nicaragua. Currently, there is a border dispute in this area (the territorial
limit between Nicaragua and Honduras is established in part by the Negro River) stemming
from the change the river suffered with Hurricane Mitch in 1998. The Estero Real (137km,
including the Tecomapa and Villanueva from which junction it forms) runs through an extensive
plain barely above sea level. This fact makes seawater to pour inland for several kilometres
at high tide. Its flow ends in deltas and serpentine estuaries with mangroves, used for
shrimp farming.
Pacific Ocean Watershed
All the rivers that drain in the Pacific Ocean (with the exception of the Negro and Estero Real)
are short and do not carry much water. In fact, some of them dry up com-pletely during the dry
season. The Pacific Ocean watershed can be divided into three sub-units:
Maribios: the rivers that originate on the Maribios volcanic range emerge in the Chinandega and Leon plains. Subterranean springs and rainfall feed them.
Diriamba Highlands (Pueblos Plateau and Managua Highlands): there are numerous parallel currents ending in sandy beach-heads that start in the Diriamba Highlands and are responsible for the shape of the coastline along this area.
Rivas: the rivers that originate along the Rivas isthmus are the shortest of the
Pacific Region. They flow through low hills and some of them dry up completely at certain
points of their course during the dry season.
Lake Managua (Xolotlan)
Lake Managua, or Xolotlan, is the second largest lake in Middle America. It has an area of
1,025 square kilometres. Its depth is no greater than seventeen metres. Its surface area
varies with the dry and rainy seasons. It is barely thirty-nine metres above sea level.
The lake has an irregular shape, being divided into two masses connected by a strait
between the Chiltepe and Panami peninsulas. It is surrounded by volcanic formations:
Momotombo; Momotombito; Chiltepe peninsula; as well as the crater lagoons of Xiloa,
Nejapa, Asososca, and Tiscapa, the last three found within the capital’s city limits
(Asososca provides Managua with drinking water).
Contrary to popular belief, the Tipitapa River is not the drainage point of Lake Managua.
Occasionally, after heavy rains, the Xolotlan does overflow into the Tipitapa River and pours
into Lake Nicaragua. Such was the case when Hurricane Mitch hit the country in 1998 and the two
lakes became virtually one huge mass of water. Normally, however, Lake Managua’s waters are lost to
evaporation due to the aquatic mirror exposed to the summer winds. Indeed, Lake Managua is almost
permanently covered by a thin layer of clouds during the day. The high peaks of the Central
Region protect these clouds from the winds so that they act as a mirror along with the water,
multiplying the evaporative effect of the rays of the sun.
The southern shore does not receive any rivers due to the porous volcanic soil in this
area that absorbs the waters much like a sponge. This condition keeps the zone between Tipitapa
and the international airport permanently humid, causing yearly flooding of the peripheral
settlements around Managua. The lake exhibits numerous islands, most of which are of volcanic origin. Among the more
important ones are: Ometepe (276km² in area), an important tourist attraction formed by volcanoes
Concepcion and Maderas; Zapatera island, the remains of a highly eroded volcano, and where ancient
Pre-Columbian petrogliphs and ceramics can be found; the Granada islets, an archipelago of some
three hundred tiny islands, a major tourist destination, product of either an avalanche or a
volcanic explosion; and the Solentiname archipelago, facing the city of San Carlos (capital
of Rio San Juan Department), which houses great variety of birds and an art co-operative.
This magnificent lake, which the Spanish conquistadors called the Fresh Water Sea, is
home to very diverse aquatic life. Among other interesting animals, the lake is home to fresh
water swordfish and large bull sharks (Carcharhinus leucas).
Most Nicaraguans seem to believe that these sharks are fresh water, but that is a misconception.
These animals have adapted to surviving in both fresh and salt-water environments and use the
San Juan River as the gateway to the lake from the Caribbean Sea. Most of the rivers that drain their waters on the western shore of the lake are very small,
much like their counterparts that drain on the Pacific Ocean, and irrigate rich agricultural lands
(Ostayo, Majaste, El Limon, Enmedio, Gil Gonzalez, Ñocarime, and Las Lajas). On the northern portion
close to Granada, however, we have two slightly larger rivers: Ochomogo (with an extension of 25 kilometres),
born west of Nandaime, drains across Zapatera island and carries a large amount of sediments that are
slowly breaching the gap between the mainland and the island; and Manares, which originates south of
Mombacho volcano and drains a series of small lagoons located at the foot of the volcano. These are fairly
untouched and house rich fauna.
The Eastern Shore of the lake is the drainage point to much larger and economically important rivers.
These rivers have their points of origin on the Central Highlands. Among these are: Malacatoya (122
kilometres in length), with its drainage point located on the northeastern shore of the lake, is dammed
at Las Banderas plains forming the artificial lake Las Canoas which is used to generate hydroelectric power
on the one hand, and irrigate agricultural lands on other. Its main tributaries are the Boaco, Teosinal,
and Ayoja Rivers. Next to its drainage point, which is marshy, there are extensive rice fields. Following
immediately to the southeast, we find the Tecolostote River, with an extension of 55 kilometres, which is
susceptible to periodic flooding. Next we find the Mayales River, with a length of 80 kilometres, formed
by the junction of the Cuapa and Pirae Rivers, which borders the city of Juigalpa and provides it with
drinking water. Following the Mayales, we find three rivers that drain the Chontales plains: the Ojocuapa,
Lovago, and Acoyapa. These rivers irrigate extensive pastures used for cattle raising. The Tepenaguasapa,
with an extension of 62 kilometres, irrigates rice fields. Finally, the Camastro and Tule Rivers descend
from the Yolaina mountain range on the southeastern shore of the lake, and were used to deliver precious woods.
The rivers that drain on the southern shore of Lake Nicaragua originate in Costa Rica in the Guanacaste
volcanic ranges. They include the Sapoa, Frio, Orosi, and Toro (among many others). The Guatuso Indians
inhabited the areas around these rivers in the 1800s, until rubber tree workers and loggers displaced them.
Before reaching its destination, it splits in two: the largest branch goes on a southerly course into
Costa Rica, draining at Barra del Colorado; while on the Nicaraguan side the other branch splits into
several narrower currents that eventually form a delta before draining in the San Juan del Norte Bay. The
southern bank of this river determines the border between Nicaragua and Costa Rica for much of its course,
and the use of its waters has been a source of territorial conflict between the two countries up to the
present (see section on Political Geography – Current Territorial Conflicts). The San Juan River, as
attested by the Cañas-Jerez Treaty signed in 1858, belongs exclusively to Nicaragua.
The Punta Gorda River shows a large number of rapids and small drops. Settlers of the Nueva Guinea region
have taken residence along the first few kilometres of its 115 kilometre run and deforested along its banks.
The Sikia and Mico Rivers originate in the Chontales hills and are used to irrigate pasturelands for
livestock production. The Rama originates in Yolaina and its course covers extensive tracts of rain forest.
The Escondido is navigable along its whole course from Rama City up to its drainage point in Bluefields
Bay and it is still used as the most efficient access route to the Caribbean
other than air travel. Sadly, however, deforestation during the past fifty years has made the river susceptible
to flooding as the riverbanks have lost their strength and the riverbed has widened disproportionately. As
the trees disappear, their roots can no longer protect the banks from the erosive strength of excess waters.
Little by little, then, the banks lose their shape and the river becomes wider. An extra side effect of this
process is that the amount of sediments being dumped into Bluefields Bay is increasing excessively, thus
putting at risk the survival of Bluefields Lagoon itself and forcing the local authorities to spend much
needed capital resources in dragging the lagoon bed.
The Grande de Matagalpa River is the second longest of Nicaragua, with 465 kilometres in length, and a
watershed of some 18,000 square kilometres. It originates in the mountains north of the city of Matagalpa,
flowing on a southward direction towards the valley of Sebaco, where it turns east. Among its numerous tributaries,
the Tuma is the most important.
The Tuma, with a 180-kilometre course, originates close to San Rafael del Norte in the Department of
Jinotega. It has been dammed at Apanas valley, forming the artificial Lake Apanas used to generate hydroelectric
power. Its main tributaries are Yaoska, Iyas, Wilike, and Lisawe, where Sumu villages used to be located up
until recently. It joins the Grande de Matagalpa at San Pedro del Norte, from which point the Grande is navigable,
acquiring widths of up to 300 metres.
The Prinzapolka’s main tributary is the Bambana (143km), which is very sinuous. Both rivers descend from
the mining districts of Siuna, Bonanza and Rosita, and were used in the past to transport minerals.
Closer to the Caribbean, the Prinzapolka runs through an extensive marshy area and splits in two:
Prinzapolka proper and Wappasiksa. At one point, these rivers used to carry lumber logged around the dense
forests that used to exist along their courses. Much of the forests in the Caribbean Region have decreased in
size due to the undeterred expansion of the agricultural frontier on the one hand, and the unscrupulous
exploitation of the forests’ resources on the other (see section on Climate).
. The Kukulaya drains in Wouhnta lagoon while the Wawa drains in Karata lagoon. The main tributary of the
Wawa is the Likus, which drains the pine-covered Miskito plains.
It originates from the junction of two rivers: the Comali (Honduran) and the Tapacali (Nicaraguan),
close to El Espino. Along its northern shore, it has sandy banks were gold may be found. Its main tributaries
in this initial part of its course are the Esteli, Yali, Monte Cristo, Jicaro, Pantasma, Cua, and Poteca.
Along the central portion of its course, it forms canyons with treacherous rapids, making navigation difficult
even for native canoes. The canyons can attain depths of up to ninety metres. This area is barely inhabited.
It is here that it receives its two main tributaries: the Bocay (115 kilometres long) and the Waspuk
(138 kilometres) which is the sacred river of the Sumu natives.
East of the Waspuk, the Coco becomes navigable by medium-sized vessels as it exits the Central Highlands
and runs trough a broad plain dotted with numerous Miskito villages. It drains at Gracias a Dios Cape,
forming a small delta. The amount of sediments that this river carries darkens the water of the Caribbean
Sea at the point of entry and for several kilometres off shore.
Its waters are not clear due to the alluvial debris carried by several rivers in the form of
muddy currents along the northern shore, and the sewage from the city of Managua on the
south¬eastern shore. The amount of sediments, combined with the shallow nature of the lack,
makes the waters seem permanently muddy. Although most people attribute the extensive pollution
of the lake to the direct dumping of Managua’s raw sewage, that is not the case. Managua’s
sewage system has contaminated an area of 8 square kilometres, which is not much compared
to the size of the lake. Rather, other reasons are responsible: pesticides and fertilisers
washed onto the rivers that feed the lake; sewage of communities located along its shores;
and dumping of dangerous chemicals from factories. Pollution levels will lower thanks to recent
legislation banning direct dumping of chemicals and the construction of a new sewage treatment
facility to service Managua’s more than one million inhabitants. There is also a new project
underway to clean up the lake and it is expected that by 2015 its waters will be suitable
for human consumption.
Lake Managua Watershed
Four large rivers originating in Esteli, Jinotega, and Matagalpa pour their waters into Lake
Managua’s northern shore (Sinecapa, Viejo, Pacora, and San Antonio), as do many smaller ones.
Lake Nicaragua (Cocibolca)
With an area of 8,264 square kilometres, it is the sec-ond larg¬est lake in Latin America,
only surpassed by Lake Titicaca (between Bolivia and Peru). It has an oval shape, and its
main axis has a length of 160 kilometres and a width of about 60 kilometres. Its altitude is
thirty-one metres above sea level, and a nineteen kilometre-wide isthmus separates it from the
Pacific Ocean. Its waters drain into the Caribbean Sea via the San Juan River.
Sketch of island formation in Lake Nicaragua
Sunset over Granada Islets on Lake Nicaragua
Lake Nicaragua Watershed
The rivers that drain their waters on Lake Nicaragua can be classified by their drainage point into
those that empty along the Rivas isthmus; those that empty their waters on the northeastern shore;
and those that flow towards the southern shore of the Lake, along the Costa Rican border.
San Juan River Watershed
The San Juan River drains Lake Nicaragua. It has an extension of 190 kilometres from San Carlos (drainage
point of Lake Nicaragua) to San Juan del Norte (drainage point of San Juan River). It reaches widths of up
to 300 metres in some locations. Rapids exist at different points along its course as the river descends
thirty metres from the lake to the Caribbean Sea. In front of El Castillo, a colonial fortress, the rapids
make navigation difficult, which was one of the reasons why the Spanish authorities decided to build the
fortress at that location.
Indio, Maiz, and Punta Gorda Rivers Watershed
These three rivers go down from the Yolaina and Chiripa Mountains. The area is almost totally uninhabited,
and is now part of the Biological Reserve Indio-Maiz. They drain in San Juan del Norte Bay. Their watershed
covers and area of 13,000 square kilometres and is ecologically important because of the rich biodiversity
it houses. There is also great potential for ecological tourism. More recently, the Biological Reserve
Indio-Maiz, with an extension of close to 264,000 hectares, has been declared by the United Nations Educational,
Scientific and Cultural Organization (UNESCO) as a World Biosphere Reserve. The UNESCO classification is aimed
at promoting and showing a balanced relationship between humankind and the environment. Nicaragua, in turn,
acquired the responsibility of protecting the Reserve.
Escondido River Watershed
The Escondido River, with a length of 88 kilometres, is formed by the junction of three major rivers:
Sikia, Mico, and Rama. Its total watershed, then, is of some 13,000 square kilometres.
Wawashan,Kurinwas, Grande de Matagalpa Rivers Watershed
The Wawashan and Kurinwas Rivers drain their waters in Pearl Lagoon. Their courses run through rain forests
from which were extracted precious woods in the past. Rich wildlife can be found throughout their watersheds.
Prinzapolka River Watershed
The Prinzapolka River’s watershed covers an area of about 8,000 square kilometres. The river itself has a
length of 245 kilometres and half of its course is navigable by small vessels.
Kukulaya and Wawa Rivers Watershed
The Kukulaya and Wawa rivers have extensions of 140 and 160 kilometres respectively, running through a
heavily forested region west of Puerto Cabezas in the northeastern portion of the country. Both are navigable
along their latter twenty-five and fifty kilometres respectively. Up until the first quarter of the twentieth
century, large banana plantations existed along their courses.
Coco, Segovia,
or Wanki River Watershed
The Coco, Segovia, or Wanki River (depending on the chosen language and historical period of preference)
is the longest in Central America, with an extension of 680 kilometres, almost crossing the isthmus from
side to side.
Seas and Coastlines