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SAN ROQUE RESERVOIR

A view on the lake
Photo.
Photo: J.G.Gavilan

A. LOCATION

  • Province of Cordoba, Argentina.
  • 31:21S, 64:30W; 600 m above sea level.
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B. DESCRIPTION

San Roque Reservoir is located in the Provionce of Cordoba at 600 m above sea level in Punilla Valley. It was created by the construction of the dams - the first one was built in 1888 and the second one, only a few meters distant from the former dam, replaced it in 1944 - for supplying tap water to the city of Cordoba, covering irrigation water needs, controlling floods, hydroelectric power generation and recreational purposes. The Cosquin and San Antonio Rivers and Las Mojarras and Los Chorrillos Streams flow into the reservoir, which is drained by the Suquia.

The reservoir is situated on an inverse fault by which Punilla Valley was formed. The risen botck (eastern side) corresponds to the Sierras Chicas. Geologically, it lies on a metamorphic crystalline basement covered by continental tertiary sediments, though there are different types of intrusion in its margilal parts, such as granite and diorite in the western margin, crystalline schist and limestone in the eastern margin, and quarternary deposits in the northern and southern margin.

The catchment area lies in a moderate subtropical climate with an average annual precipitation of 650 mm and an average humidity of 65%.

San Roque Reservoir plays an important role as the source of water for domestic uses in Cordoba city as well as for industries and irrigation. Its significance as hydroelectric power generator depends on the requirements from industrial and other sectors. Besides, it has encouraged the development of recreational activities in the territory's central area, e. g. sport-fishing, various water sports, motor boat races, cruising, etc. More than 50% of facilities for tourist reception in Cordoba Province are concentrated in the Valley of Punilla. Villa Carlos Paz area-an entrance gate to Cordoba Mountains-has the highest tourist density, and offers a variety of bathing sites (Q, 1).

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C. PHYSICAL DIMENSIONS (2)

Surface area [km2] 17
Volume [km3] 0.19
Maximum depth [m] 25.0
Mean depth [m] 11.0
Water level Regulated
Normal range of annual water level fluctuation [m] 8.0
Length of shoreline [km] 54.5
Residence time [yr] 0.1-0.7
Catchment area [km2] 1,750
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D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL (Q)

  • Sketch map: Fig.
    SAM-06-0l.
  • Bathymetric map:
    Fig. SAM-06-02.
  • Names of main islands:
    None.
  • Number of outflowing rivers and channels (name):
    1 (Suquia).

D2 CLIMATIC

  • Climatic data (2)
Cuesta Blanca, 1976-1977
Min Max Ann.
Mean temp. [deg C] 0 38 16
Precipitation [mm] - - 650

* Rainy period: September-May.

Villa Carlos Paz, 1983 (4)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
Mean temp. [deg C]* 21.5 18.6 14.7 15.9 13.0 8.6 7.7 9.2 10.8 17.6 18.3 20.7 14.7

* Based on daily extreme values.

  • Number of hours of bright sunshine (Buenos Aires):
    2,519 hr yr-1.
  • Solar radiation:
    5.4*1-10.9*2 MJ m-2 day-1. *1 Winter. *2 Summer.

    Fig. SAM-06-01
    Sketch map (Q).

    Fig. SAM-06-02
    Bathymetric map [m](Q).
  • Water temperature [deg C](3)
Station A*1, December 1984-November 1985
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
S*2 26.0 25.5 21.0 19.5 17.0 12.0 - 10.0 - 19.5 24.0 22.5
15 - - - 19.0 16.5 12.0 - 10.5 13.5 18.0 20.0 21.0
20 18.5 19.0 20.0 - - - - - - - - -

*1 The centre of the lake. *2 Surface.

Station 1008*, 1986 (5)
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0-4 - - 24.5 23.2 - 16.0 - 12.5 - 21.0 - -
5-9 - - - 22.5 - 15.0 - - - 19.5 - -
10-14 - - - 21.5 - 14.6 - 13.0 - 17.5 - -
15-18 - - 22.0 - - - - - - 18.0 - -

* Gems-Agua Project.

  • Freezing period:
    None.
  • Mixing type:
    Monomictic.
  • Notes on water mixing and thermocline formation:
    Unstable.
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E. LAKE WATER QUALITY

E1 TRANSPARENCY [m](3)

Station A
Nov
1984 0.70
1985 2.10

E2 pH (3)

Station A, October 1984-November 1985
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
S* - - - - - - - - - 7.2 8.2 7.9
15 - - - - - - - - - 6.8 7.1 7.3
S 8.1 7.4 7.8 7.5 7.7 7.2 - 7.7 8.0 7.7 8.5 -
15 - - - 7.2 7.5 7.8 - 7.9 8.0 8.6 7.3 -
20 6.4 6.6 6.8 - - - - - - - - -

* Surface.

E4 DO [mg l-1]

Station A, October 1984-November 1985 (3)
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
S* - - - - - - - - - 6.54 9.02 7.76
15 - - - - - - - - - 2.18 5.33 3.96
S* 7.0 6.46 6.73 6.0 6.88 8.64 - 10.16 11.25 8.94 9.92 -
15 - - - 5.84 6.40 8.48 - 9.92 10.66 6.15 6.81 -
20 3.20 0.16 0.0 - - - - - - - - -
Station A, 1986 (5)
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0-4 - - 6.9 6.5 - 8.3 - 8.3 - 8.4 - -
5-9 - - - 4.9 - 8.3 - - - 7.5 - -
10-14 - - - 4.7 - 8.3 - 7.8 - 5.9 - -
15-18 - - 1.2 - - - - - - 3.4 - -

* Surface.

E6 CHLOROPHYLL CONCENTRATION [micro g l-1](3)

Station A, November, 1984-1985
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
S* - - - - - - - - - - 30.50 13.35
15 - - - - - - - - - - 0.0 2.67
S* - 12.81 4.27 2.13 10.6 10.6 - 12.8 34.1 21.3 0.0 -
15 - - - - 0.0 10.6 - 6.54 17.0 0.0 0.0 -
20 - 9.48 4.27 8.54 - - - - - - - -

* Surface.

E7 NITROGEN CONCENTRATION (5)

  • NH4-N [mg l-1]
Station A, 1986
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0-4 - - .07 .1 - .056 - .015 - .076 - -
5-9 - - - .1 - .056 - - - .192 - -
10-14 - - - .1 - .056 - .045 - .258 - -
15-17 - - .173 - - - - - - .511 - -
  • (NO2 + NO3)-N [mg l-1]
Station A, 1986
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0-4 - - 7.63 1.32 - .035 - 1.15 - 1.263 - -
5-9 - - - 1.30 - .020 - - - 1.12 - -
10-14 - - - 1.26 - .095 - 1.076 - 1.043 - -
15-18 - - 4.71 - - - - - - 1.11 - -

E8 PHOSPHORUS CONCENTRATION (5)

  • PO4-P [mg l-1]
Station A, 1986
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0-4 - - .010 .012 - .028 - .003 - .003 - .006
5-9 - - - .020 - .030 - - - .016 - -
10-14 - - - .025 - .033 - .009 - .020 - -
15-18 - - .176 - - - - - - .033 - .124

E9 CHLORIDE CONCENTRATION [mg l-1](5)

Station A, 1986
Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0-4 - - 6.6 9.4 - - - 15.5 - 30.0 - -
5-9 - - - 9.4 - 3.0 - - - 29.0 - -
10-14 - - - 9.4 - 4.5 - 13.5 - 29.0 - -
15-18 - - 5.7 - - - - - - 28.0 - -
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F. BIOLOGICAL FEATURES

F1 FLORA (Q)

  • Emerged macrophytes:
    None.
  • Floating macrophytes:
    None.
  • Submerged macrophytes:
    Elodea ernstae is found occasionally.
  • Phytoplankton
    Spring: Cyanophyta abundant (Anabaena and Microsystis).
    Summer: The same as in spring and Melosira granulata.
    Autumn: Melosira and greater abundance of Anabaena.
    November 1985: Diatoms.
    Submerged and floating aquatic vegetation appeared after the floods for the first time in 1987.

F2 FAUNA (Q)

  • Zooplankton
    Rotifera (Brachionus, B. calyciflorus, B. angularis, B. plicatilis, Euchlanis, Keratella cochlearis, Platyias, Lecaneluna, Monostyla, Trichocerca, Asplanchna, Polyarthra, Filinia, Pompholyx, Hexarthra, Conochiloides, Collotheca); Crustacea (Notodiaptomus, Acanthocyclops, Diaphanosoma, Daphnia, Ceriodaphnia, Moina, Bosmina).
  • Benthos
    Oligochaeta (Branchiura sowerbyi, Limnodrilus hoffmeisteri, L. udekemianus, L. sp., Tubifex tubifex, Dero obtusa, Pristina osborni, Pristina sp., Inais variabilis); Hirudinea (Glossiphoniidae, Erpobdellidae, Semiscolecidae); Insecta (Chironomidae, Ceratopogonidae, Trichoptera, Ephemeroptera); Mollusca (Pisidum, Physa, Lymnaea).
  • Fish
    Bryconamericus iheringi, Cichlaurus facetus, Cnesterodom decenmaculatus, Corydoras, paleatus, Hoplias malabaricus malabaricus, Jenynsia lineata lineata, Oligosaurus jenynsi, Paradon tortuosus tortuosus, Pimelodella laticeps, Plecostomus cordovae, Rhamdia sapo, Astyanax cordovae, A. eigenmanniorum, Bryconamericus eigenmanni, Loricaria catamarcensis, Pygidium corduvense, Basilichthys argentinensis bonariensis, Jenynsia lineata lineata, Pimelodus albicans, Pimulodus clarias, Leporinus obtusidens, Salminus maxillosus, Percichthys trucha, Cyprinus carpio.

F3 PRIMARY PRODUCTION RATE [mg O2 m-2 hr-1](3)

Station A, October 1984-November 1985
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
Gross production - - - - - - - - - 80 2,168 1,683 -
2,004 - 1,287 280 470 385 - 725 399 1,107 538 - -

F5 FISHERY PRODUCTS (6)

  • Annual fish catch
    There is no commercial exploitation.
  • Fishery products other than fish
    There is no commercial exploitation, except the catch of shrimps (without an industrial organization) used as bait.

F6 PAST TRENDS

Not available.

F7 NOTES ON THE REMARKABLE CHANGES OF BIOTA IN THE LAKE IN RECENT YEARS (3)

    Phytoplankton:
    Low diversity and very frequent blooms (two blooms may take place within a period of one month).
    The high productivity, high chlorophyll concentration and its distribution, frequent algal blooms with Cyanophyta dominance, hypolimnetic lack of oxygen during summer time and poor transparency indicate that this lake ecosystem is on a high level of eutrophication. It may reach hypertrophic stage, if nutrient loadings due to domestic and industrial sewage, deforestation in the catchment area, and other important environmental impacts are not successfully controled.
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G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA (6, 9)

[%]
Natural landscape
- Woody vegetation 48.8
- Herbaceous vegetation 47.8
Agricultural land 3.4
Total 100.0
  • Types of important woody vegetation:
    Upland forest and scrub.
  • Types of important herbaceous vegetation:
    Grassy and pasture grounds.
  • Main kinds of crops
    Experimental plantation of potato and man-made forests in the San Antonio Basin.
  • Levels of fertilizer application on crop fields:
    None.
  • Trends of change in land use:
    Not available.

G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE (6)

Gross product per year No. of persons engaged No. of establishments
Secondary industry
Mining and avian industries N.A. N.A. N.A.
  • Numbers of domestic animals in the catchment area:
    Not available.

G3 POPULATION IN THE CATCHMENT AREA (10)

The most densely populated locality of the catchment area has less than 30,000 inhabitants. Some localities duplicate their population during summer time.

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H. LAKE UTILIZATION

H1 LAKE UTILIZATION (Q)

Source of water, recreation (swimming, sport-fishing, yachting), control of floods, hydroelectric power generation and irrigation.

H2 THE LAKE AS WATER RESOURCE (2)

1977
Use rate [m3 day-1]
Domestic 400
Irrigation 3,300
Industrial*1 1,100
Others*2 260

*1 Additionally power plant: 26,000[kW yr-1].
*2 Water for municipal purposes (industrialwastewater dissolution during low water).

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I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS

I1 ENHANCED SILTATION (2)

  • Extent of damage:
    Not serious.
  • Supplementary notes:
    A volume of 134,600 m3 was lost during past fifty years. Sedimentation rate: 2,000 [m3 yr-1].

I2 TOXIC CONTAMINATION

Not available.

  • Supplementary notes (Q)
    Pollution caused by human settlements along the Cosquin River flows into the lake. The San Antonio River - the most important one - watershed has not a large number of human settlements, but an upstream uranium exploitation plant and a sigificant concentration of population on the lake shore (Villa Carlos Paz and its surroundings) are the sources of pollution.

I3 EUTROPHICATION (3)

  • Nuisance caused by eutrophication
    Unusual algal bloom: Anabaena, Microcystis, Melosira granulata and M. binderana.
    Disturbed filtration in cleaning beds.
    Foul odour of tap water.
    Harms to fishery products: Mackerel mortality.
  • Nitrogen and phosphorus loadings to the lake [tons yr-1](2)
Sources Industrial Domestic Agricultural Natural Total
T-P - 45 140 5 190
  • Supplementary notes (10)
    Winter blooms of Cyanophyta tend to reach high levels. Countermeasures implemented to diminish eutrophication are
    1. Studies are being carried out to detect the rate of nutrient loading in the San Antonio and Cosquin Rivers.
    2. Limiting loadings to the San Antonio River.
    3. Contamination studies to determine water characteristics of the Cosquin and San Antonio Rivers.
    4. Limnological studies on the reservoir (navigation licenses will be reduced because of fuel toxicity).
    5. The Provincial Hydraulics Department has implemented the legislation that hotels should be supplied with treatment plants.
    6. Forestation programs in non-forested areas and prohibition about the formation of lots in many sectors so as to prevent the action of mineral substances.
    7. It has been ordered to the city of Carlos Paz (10,000 inhabitants) to implement a tertiary treatment plant.
    8. Aluminium sulfate, approximately 1,500 tons per year, and activated carbon are used in blooming time.

I4 ACIDIFICATION (10)

  • Extent of damage:
    Serious.
    Strong acidity (pH: 3) in the San Antonio River, caused by H2SO4 discharge, at Los Gigantes and the Cuesta Blanca water intake.
    Damages: Fish and macrophyte mortality and dermatitis in human beings.
  • Past trends:
    Not available.
  • Supplementary notes
    Prohibition of H2SO4 discharge in the uranium plant is in force at present.

I5 OTHER HAZARDS (10)

Radioactive contamination caused by uranium exploitation.

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J. WASTEWATER TREATMENTS

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA

(f) Other case (10). The incidence of agricultural and stockfarm contamination is not known, and significant developments of such activities are not expected in this area. The number of large-scale industrial plants is also few, with an outstanding exception of uranium exploitation at Los Gigantes. The generation of pollutants in the catchment area is mostly due to tourism and wastewater from human settlements. Urban wastewater flows into the rivers and the reservoir without any treatment; there are treatment plants in some localities and hotels, but they are hardly controlled by local authorities, for instance the municipal office of Villa Carlos Paz.

J2 APPROXIMATE PERCENTAGE DISTRIBUTION OF POLLUTANT LOADS (Q)

[%]
Non-point sources
- (agricultural, natural and dispersed settlements) 5
Point sources
- Municipal 90
- Industrial 5
Total 100

J3 SANITARY FACILITIES AND SEWERAGE (10)

  • Percentage of municipal population in the catchment area provided with adequate sanitary facilities (on-site treatment systems) or public sewerage:
    Not available.
  • Percentage of rural population with adequate sanitary facilities (on-site treatment systems):
    Low rural population, without sanitary facilities.
  • Municipal wastewater treatment systems
    No. of tertiary treatment systems: None.
    No. of secondary treatment systems: 2 or 3.
    1. In La Falda (one in operation).
    2. In Sta. Maria (stabilization lagoons).
      No. of other types: There are various compact plants in some hotels and vacation lodgings (without tertiary treatment).
  • Industrial wastewater treatment systems:
    None.
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K. IMPROVEMENT WORKS IN THE LAKE (Q)

K1 RESTORATION

None.

K2 AERATION

None.

K3 OTHERS (10)

The elimination of algae through superficial mechanic aspiration in being studied at a pilot level, to be applied to high algal concentration areas at water intakes, where they are concentrated by wind.

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L. DEVELOPMENT PLANS (10)

There is a budget scheme for 1987 to undertake the construction of a dam in Cuesta Blanca area, upstream of Carlos Paz, on the San Antonio River. It is to control water flux for preventing floods and especially to supply potable water to the city of Carlos Paz and its surroundings.

The purification of sewage of Carlos Paz is planned in the city of Villa Carlos Paz. In the beginning, this project will cover 10,000 inhabitants out of the total 60,000, which will be covered later on in successive stages.

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M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS (11)

M1 NATIONAL AND LOCAL LAWS CONCERNED

  • Names of the laws (the year of legislation)
    1. Law 7,343 (August 29th, 1985). Principles regulating preservation, maintenance, defense and improvement of environmental conditions.
    2. Code of Waters of the Province of Cordoba
  • Responsible authorities
    1. Original bill elaborated by legislators Ruben Martin and Alfredo 0rgaz. Subsecretariat of Environmental Negotiations.
    2. Provincial Hydraulics Department
  • Main items of control
    1. Law 7,343: Soil, air, water and biotic components.
    2. Code of waters: water.

M2 INSTITUTIONAL MEASURES

  1. Empresa Provincial de Obras Sanitarias, Ciudad de Cordoba (Provincial Sanitary Works Department, City of Cordoba)
  2. Subsecretaria de Gestion Ambiental, Ciudad de Cordoba (Subsecretariat of Environmental Negotiations)
  3. Direccion Provincial de Hidraulica, Ciudad de Cordoba (Provincial Hydraulics Department, City of Cordoba)

M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES

  1. INCYTH: Instituto Nacional de Ciencia y Tecnica Hidricas (National Institute for Water Science and Technology).
  2. CTUA: Centro de Tecnologia del Uso de Agua (Centre of Technology for Water Use).
  3. CIHRSA: Centro de Investigaciones Hidricas de la Region Semi-Arida (Centre for Water Studies of the Semi-Arid Region).

N. SOURCES OF DATA

Questionnaire filled by Dr. J. G. Gavilan, Instituto Nacional de Ciencia y Tecnica Hidricas, Centro de Tecnologia Deluso del Agua, Ezeiza, Argentina.

  1. Cachi, J. C. Vareaciones planctonicas del Embalse San Roque, Cordoba, Republica Argentina, Tema 1, No. 4, Empresa 0. S. N..
  2. Gavilan, J. G. (1981) Estudios de calidad de agua en el Embalse San Roque, Prov. de Cordoba, Republica Argentina, CTUA-INCYTH.
  3. EP0OS-Ciudad de Cordoba: Busso, F. & Ormeno, N. Personal communication.
  4. Dereccion Provincial de Hidraulica.
  5. Laboratorio CTUA-INCYTH, Proyecto GEMS/AGUA.
  6. CIRHSA-CONICET: Donatti, 0. Personal communication.
  7. Corigliano, M. C. (1975) Estudio ecoligicos sobre la comunidad zooplanctonica del Lago San Roque, Tesis para doctorado Universidad Nacional de Cordoba.
  8. Bonetto, A. A. & Di Persia, D. H. (1984) The San Roque Reservoir and other man-made lakes in the Central Region of Argentina. "Ecosystem of the World 23: Lakes and Reservoirs" (ed. Taub, F. B.), Chapter 22, pp. 541-556. Elsevier Science Publishers B. V., Amsterdam.
  9. Barbeito, 0., Santa, J. A. & Herrero, M. (1978) Erosion y Sedimentacion en la cuenca del Rio San Antonio, Cordoba, Informe preliminar INCYTH- CONICET, CIHRSA, Villa Carlos Paz.
  10. EPOS-Ciudad de Cordoba: Bertucci, C. Personal communication.
  11. Ambiente y Recursos Naturales (Octubre-Diciembre 1985) Revista de Derecho, Politica y Administracion, 2 (4).
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