The Emilio López Zamora dam, also known as the Ensenada dam, is a dam with a water treatment plant in

Ensenada Ensenada ("inlet") is a city in Ensenada Municipality, Baja California, situated on the Pacific Coast of Mexico. Located on Bahía de Todos Santos, the city had a population of 279,765 in 2018, making it the third-largest city in Baja Californ ...

, Baja California, Mexico, on the basin of the Ensenada stream. Its main use is the containment of flash floods, and as a water supply for the city. It was built in 1976 and is administered by Mexico's (CONAGUA).

Characteristics

The dam has a reservoir capacity of about 3.75 million cubic meters. However, the useful capacity is estimated to be about 2.61 million cubic meters, since the bottom has filled with mud and debris. The area of the reservoir is 54 hectares. The dam is a concrete gravity dam with a length of 200 meters and a maximum height of 34 meters. The width of the crest is 8.5 meters. It has a drop spillway with a maximum drain rate of 30 meters cubic per second. Below the dam, there is a water treatment plant with a capacity of 150 liters per second. It takes water from the reservoir and treats it to drinking level to be sent to the distribution network with a pumping system.

Operation

The Emilio Lopez Zamora dam is operated by Mexico's National Water Commission. In 2018 preventive maintenance was carried out on the dam with an investment of 2 million pesos.

History

Built in 1976, it was named for hydraulic engineer Emilio Lopez Zamora, who was the Director of Agriculture in Baja California. The purpose of the dam was to contain flash floods from the local streams and

surface runoff Surface runoff (also known as overland flow or terrestrial runoff) is the unconfined flow of water over the ground surface, in contrast to ''channel runoff'' (or ''stream flow''). It occurs when excess rainwater, stormwater, meltwater, or other ...

, and to supply water to the city. In 1993 an area of 72 hectares was expropriated from the nearby Adolfo Ruiz Cortines community to be part of the reservoir.

Problems and risks

Drought

The contribution from the dam to the water supply is sporadic, because of the irregularity of the Ensenada stream. The dam has reached very low levels of accumulated water, due to poor rainfall during long drought periods, as occurred in 2014, with the dam becoming almost empty in 2015.

Overflow risk

The dam has reached its maximum capacity and activated the

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

on several occasions, most recently in 2019. During the intense rainfall of March 4, 1978, ( in 24 hours), there was an overflow scare and sandbags were placed at the top of the crest. There is uncertainty among the nearby population concerning a potential overflow, with the risks balanced by the fact that the dam did not overflow during the intense rains of 1978, and since then there have not been similar rainfall levels. The real risk of overflowing is increased when the reservoir partially fills with sand and mud due to the lack of dredging.

Garbage and pollution

The dam has been illegally used for dumping raw sewage. This situation has worsened due to the population increase in the neighboring communities, including irregular settlements, and with a construction company reported for illegal spilling. On the surface and the edges, garbage and litter, such as plastic bags and bottles, is visible.

Suicides

In previous years, people have committed suicide by jumping from the dam, until fences were installed to prevent access.

Other community uses

The dam also serves as a vehicular and pedestrian bridge. In the 2002 the Ensenada city council declared the reservoir and surrounding area as an ecological reserve, and in 2007 it was determined to be a protected zone. Plans have been introduced to create a park around the dam or a series of parks from the dam to the ocean following the stream. The reservoir has been used as a training site for competitive kayaking and boating.

Flora and fauna

Vegetation

The vegetation around the dam consists of, in order to distance to the water,

marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...

(next to the water) with species such as ''

Spartina foliosa ''Sporobolus foliosus'' is a species of grass known by the common name California cordgrass. It was reclassified from ''Spartina foliosa'' after a taxonomic revision in 2014. It is native to the salt marshes and mudflats of coastal California and ...

and Sarcocornia pacifica'';

coastal sage scrub Coastal sage scrub, also known as coastal scrub, CSS, or soft chaparral, is a low scrubland plant community of the California coastal sage and chaparral subecoregion, found in coastal California and northwestern coastal Baja California. It is ...

, and in the higher areas away from the water coniferous forest type trees such as pines,

junipers Junipers are coniferous trees and shrubs in the genus ''Juniperus'' ( ) of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely species distribution, distributed throughout the Northern Hem ...

, and

calocedrus ''Calocedrus'', the incense cedar (alternatively spelled incense-cedar), is a genus of coniferous trees in the cypress family Cupressaceae first described as a genus in 1873. Three species are native to eastern Asia and one to western North Ame ...

Fish

Different fish species have been documented in the reservoir, including exotic species such as threadfin shad (''

Dorosoma petenense The threadfin shad (''Dorosoma petenense'') is a small pelagic freshwater forage fish common in lakes, large streams and reservoirs of the Southeastern United States. Like the American gizzard shad, the threadfin shad has an elongated dorsal fin, ...

''), channel catfish (''

Ictalurus punctatus The channel catfish (''Ictalurus punctatus''), known informally as the "channel cat", is a species of catfish native to North America. They are North America's most abundant catfish species, and the official state fish of Kansas, Missouri, Nebras ...

''), western mosquito fish (''

Gambusia affinis The western mosquitofish (''Gambusia affinis'') is a North American freshwater poeciliid fish, also known commonly, if ambiguously, as simply mosquitofish or by its generic name, ''Gambusia'', or by the common name gambezi. Its sister species ...

''), bluegill (''

Lepomis macrochirus The bluegill (''Lepomis macrochirus''), sometimes referred to as "bream", "brim", "sunny", or, in Texas, "copper nose", is a species of North American freshwater fish, native to and commonly found in streams, rivers, lakes, ponds and wetlands ea ...

''), largemouth bass (''

Micropterus salmoides The largemouth bass (''Micropterus nigricans'') is a carnivorous, freshwater, ray-finned fish in the Centrarchidae (sunfish) family, native to the eastern and central United States, southeastern Canada and northern Mexico. It is known by a v ...

''), and redbelly tilapia ('' Tilapia zillii'').

References

{{Authority control Landmarks in Ensenada Dams in Mexico Dams completed in 1976 Buildings and structures in Baja California