LOUGH REE (LAKE REE)

A view on the lakeshore

Photo.
Photo: Irish Tourist Board




A. LOCATION

  • Roscommon, Longford and Westmeath, Ireland.
  • 53:26-53:41N, 7:50-8:05W; 38 m above sea level.


B. DESCRIPTION

    Lough Ree, which is about 25 km long and 7 km wide, lies entirely on Carboniferous Limestone. While it shows some evidence of being a solution lake such as undercut rocks (1), the existence and orientation of the deep areas of the lake are consistent with an origin by ice erosion
    The lake has a very irregular shoreline with extensive reed beds and an uneven bottom. There are many sizeable islands particularly in the upper area. The greater part of the lake is shallow and less than 6 m deep, however, there are a number of deep trenches running in a north-south direction with a maximum sounding of 35 m near the middle of the lake. The catchment (Fig. 1) has a low population density. The areas west and north of the lake have a population density of less than 20 persons km-2 according to the 1981 census data. There are five towns in the catchment with populations between 1000 and 5000 people but none are likely to have any effect on the lake in terms of effluent discharge.
    Agriculture is the main activity in the catchment and there are extensive peat-mining activities just north of the lake. The peat is used largely for the generation of electricity. There are several small agri-industry plants in the catchment and light and electronic engineering, chemical and coal mining industries are significant employers.
    Lough Ree is the second largest lake in the River Shannon System after Lough Derg. It forms part of the Shannon Navigation System and its development as an amenity and recreational area for cruising is its principal beneficial use. It is also renowned as a game and coarse fishery holding excellent stocks of several species of coarse fish. The water supply for Athlone (popul. 14,000), the principal town of the region, is taken from the lake outlet, the River Shannon.
    A detailed investigation of the water quality of Lough Ree and its feeder streams was carried out in the period 1979-1981, with updates in 1984 and 1986 (Bowman, in prep.). An initial assessment indicates that the lake was not significantly affected by artificial eutrophication in the 1979 1981 period. However, a light increase in the level of algal production was noted in the subsequent examinations. The values recorded for chlorophyll a and the total phosphorus concentrations place the lake in the border between mesotrophic and eutrophic categories according to the O.E.C.D. scheme (R).


C. PHYSICAL DIMENSIONS (Q)

    Surface area [km2] 105
    Volume [km3] 0.651
    Maximum depth [m] 35
    Mean depth [m] 6.2
    Water level Regulated
    Normal range of annual water level fluctuation [m] 0.8
    Residence time [yr] 0.2
    Catchment area [km2] 4,530


D. PHYSIOGRAPHIC FEATURES (Q)

D1 GEOGRAPHICAL

  • Bathymetric map: Fig. EUR-21-01.
  • Names of main islands
    Saits (0.82 km2), Inchmore (0.865 km2) and Inchcleraun (0.577 km2).
  • Number of outflowing rivers and channels (name): 1 (R. Shannon).

D2 CLIMATIC

  • Climatic data at Mullingar, 1951-1980

    Mean temp. [deg C]
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    3.6 3.9 5.6 7.6 10.2 12.9 14.4 14 12.2 9.8 6.0 4.7 8.7
    Precipitation [mm]
    91 62 62 59 67 63 72 79 83 90 91 98 1,018
  • Number of hours of bright sunshine: 1,313 hr yr-1.
  • Solar radiation: 9.8 MJ m-2 day-1.

    Fig. EUR-21-01
    Bathymetric map [m].


  • Water temperature [deg C]

    Station 1, 1980
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0.5* - 5.0 5.5 9.0 13.0 14.0 16.0 17.0 17.5 10.5 - -
    6 - 5.0 5.5 9.0 13.0 14.0 15.5 17.0 17.5 10.5 - -
    12 - 5.0 5.3 9.0 13.0 14.5 15.5 17.0 17.0 10.2 - -
    18 - 5.0 5.3 9.0 13.0 14.5 15.5 16.5 17.0 10.0 - -
    25 - 5.0 5.5 8.7 11.5 14.5 15.5 16 17.0 10.0 - -
    27 - - - - 11.2 14.5 - - - 10.0 - -
    30 - - - 8.5 - - - - - - - -
    * Surface.
  • Freezing period: None.
  • Mixing type: Monomictic.
  • Notes on water mixing and thermocline formation
    Water was generally well mixed in this lake in the period of observation (1979-1980). Short-term thermocline formation has been observed in June- October period.


E. LAKE WATER QUALITY (Q)

E1 TRANSPARENCY [m]

    Station 1, 1980
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    - 2.8 1.7 2.0 2.5 2.4 2.8 2.0 3.0 2.3 - -

E2 pH

    Station 1, 1980
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0.5 - 8.25 8.3 8.32 8.27 8.27 8.41 8.55 8.25 8.21 - -
    6 - 8.3 8.3 8.32 8.27 8.27 8.39 8.53 8.26 8.29 - -
    12 - 8.3 8.3 8.35 8.27 8.31 8.39 8.49 8.25 8.27 - -
    18 - 8.3 8.3 8.35 8.27 8.30 8.42 8.52 8.25 8.23 - -
    24 - 8.3 8.4 8.32 8.15 8.29 8.34 8.52 8.26 8.21 - -
    27 - - - - 8.13 8.31 - - - 8.09 - -
    30 - - - 8.31 - - - - - - - -

E4 DO [mg l-1]

    Station 1, 1980
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0.5 - 9.5 9.8 9.8 10.2 9.7 10.8 11.2 9.4 10.0 - -
    6 - 9.5 9.9 9.7 10.0 9.6 10.4 11.0 9.4 10.0 - -
    12 - 9.3 9.8 9.7 10.0 9.5 10.4 11.0 9.4 9.8 - -
    18 - 9.4 9.9 9.8 10.0 9.4 10.2 10.8 9.3 9.6 - -
    24 - 9.4 9.9 9.7 8.7 9.4 10.0 10.8 9.0 9.7 - -
    27 - - - - 8.4 9.3 - - - 9.5 - -
    30 - - - 9.6 - - - - - - - -

E6 CHLOROPHYLL CONCENTRATION [micro g l-1]

    Station 1, 1980
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0.5 - 2.53 2.9* 5.89 0.34* 2.0 6.68 15.66 2.8* 7.0 - -
    6 - 2.2 2.9 0.6 6.78 14.41 - 7.3 - -
    12 - 1.66 - 4.26 0.82 0.6 6.94 12.95 2.3 7.0 - -
    18 - 2.2 - - - - 7.20 - 1.7 6.9 - -
    24 - - 6.63 5.89 - 0.9 5.50 14.95 3.1 6.8 - -
    * 0.5-6 m.

E7 NITROGEN CONCENTRATION

  • NH4-N [mg l-1]

    Station 1, 1980
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0.5 - 0.075 0.04 0.015 0.05 0.065 0.005 0.005 0.10 0.04 - -
    6 - 0.065 0.02 0.015 0.05 0.08 0.005 0.005 0.10 0.04 - -
    12 - 0.055 0.015 0.01 0.045 0.08 0.010 0.015 0.11 0.06 - -
    18 - 0.050 0.015 0.015 0.045 0.07 0.010 0.030 0.12 0.04 - -
    24 - 0.050 0.015 0.02 0.075 0.07 0.015 0.005 0.125 0.05 - -
    28 - - - - 0.085 0.085 - - - 0.06 - -
    > NO2+NO3-N [mg l-1]

    Station 1, 1980
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0.5 - 0.89 0.76 0.72 0.64 0.53 0.38 0.07 0.24 0.14 - -
    6 - 0.89 0.76 0.72 0.64 0.52 0.40 0.075 0.22 0.14 - -
    12 - 0.89 0.78 0.74 0.64 0.53 0.40 0.10 0.24 0.14 - -
    18 - 0.89 0.78 0.74 0.62 0.52 0.40 0.11 0.24 0.14 - -
    24 - 0.89 0.78 0.76 0.64 0.52 0.40 0.11 0.22 0.20 - -
    28 - - - - 0.65 0.53 - - - 0.22 - -

E8 PHOSPHORUS CONCENTRATION

  • Total-P [mg l-1]

    Station 1, 1980
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0.5 - 0.025 0.025 0.025 0.013 0.050 0.020 0.034 0.018 0.020 - -
    6 - 0.025 0.023 0.033 0.015 0.030 0.021 0.034 0.023 0.046 - -
    12 - 0.028 0.025 0.038 0.013 0.023 0.019 0.036 0.016 0.021 - -
    18 - 0.03 0.03 0.04 0.013 0.020 0.020 0.033 0.018 0.020 - -
    24 - 0.025 0.025 0.035 0.024 0.025 0.020 0.031 0.019 0.024 - -
    27 - - - - 0.020 0.018 - - - - - -
    30 - - - 0.033 - - - - - - - -


F. BIOLOGICAL FEATURES (Q)

F1 FLORA

  • Emerged macrophytes
    Sagittaria spp., Equisetum variegatum, Phragmites spp., Juncus spp.
  • Floating macrophytes: Lemna spp.
  • Submerged macrophytes
    Potamogeton spp., Elodea canadensis, Myriophyllum spp., Chara tomentosa, C. spp.
  • Phytoplankton
    Winter: Oscillatoria spp., Stephanodiscus spp., Melosira spp. Spring: Melosira spp., Asterionella spp., Oscillatoria spp. Summer: Oscillatoria spp., Asterionella spp., Anabaena spp. Autumn: Oscillatoria spp., Ceratium hirundinella, Fragilaria spp.

F2 FAUNA

  • Zooplankton
    Diaptomus spp., Cyclops spp., Daphnia hyalina, Bosmina spp., Keratella quadrata, K. cochlearis.
  • Benthos
    Platyhelminthes (Planaria torva), Oligochaeta (Eiseniella tetraedra), Hirudinea (Glossiphonia complanata), Crustacea (Gammarus duebeni), Ephemeroptera (Ecdyonurus dispar), Trichoptera (Polycentropus flavomaculatus), Coleoptera (Oulimaius tuberculatus), Mollusca (Bithynia tentaculata, Limnaea peregra, Theodoxus fluviatilis, Valvata piscinalis).
  • Fish
    Salmo salar, S. trutta*, Perca fluviabitis, Tinca tinca, Anguilla anguilla*, Coregonus elegans, Osmerus eperlanus, Esox lucius, Abramis brama, Scardinius erythrophthalmus, Rutilus rutilus. * Economically important.

F5 FISHERY PRODUCTS

  • Annual fish catch [metric tons]
    1986: 5.


G. SOCIO-ECONOMIC CONDITIONS (Q)

G1 LAND USE IN THE CATCHMENT AREA

    1980'S
    Area [km2] [%]
    - Natural landscape
    Woody vegetation 226 5
    Herbaceous vegetation 226 5
    Peatland 906 20
    - Agricultural land
    Crop field 226 5
    Pasture land 2,718 60
    - Residential area 45 1
    - Others 181 4
    - Total 4,528 100
  • Main types of woody vegetation
    Mixed evergreen predominate with lesser amounts of old deciduous broadleaf.
  • Main kinds of crops: Grass for cattle rearing.
  • Levels of fertilizer application on crop fields: Light.
  • Trends of change in land use: Increase in exploitation of peatlands.

G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE

  • Major industries
    Milk and meat processing, light mechanical engineering, electrical engineering, chemical, coal mining, timber products, food stuffs, electricity generation, peat products.
  • Numbers of domestic animals in the catchment area
    Cattle 500,000, sheep 270,000, swine 41,000, poultry 350,000.


H. LAKE UTILIZATION (Q)

H1 LAKE UTILIZATION

    Source of water, navigation and transportation, sightseeing and tourism, recreation (swimming, sport-fishing, yachting) and fisheries.

H2 THE LAKE AS WATER RESOURCE

    l980s
    Use rate [m3 day-1]
    Domestic 7,280
    Industrial 325
    Power plant 500,000


I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS (Q)

I1 ENHANCED SILTATION

  • Extent of damage: Not serious.
  • Supplementary notes: Peat silt, resulting from peat workings in the lake
    catchment, is being washed into and settling in the lake.

I3 EUTROPHICATION

  • Nuisance caused by eutrophication
    Unusual algal bloom: Mixed blue-green populations 'bloom' during calm weather.
  • Nitrogen and phosphorus loadings to the lake [t yr-1]
    150 (estimated; accurate details of breakdown not available, but mostly of natural origin).
  • Supplementary notes
    No increase in the level of planktonic algal development has been noted in Lough Ree in recent years. The lake still retains the characteristics of a water body in the transition between the mesotrophic and eutrophic categories.

I4 ACIDIFICATION

  • Extent of damage: None.
  • Past trends in hydrogen ion concentration in lake water
    No detailed historic information on the pH values in the lake. Recent data indicate the lake to be well buffered with the pH values in excess of 8.0. Lake waters are hard (mean alkalinity value: ca. 160 mg-1-1 CaCO3).


J. WASTEWATER TREATMENTS (Q)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA

    c) Limited pollution with wastewater treatment.

  • Supplementary notes: Influx of peat silt to the lake may be a source of
    bioavailable phosphorus.

J2 APPROXIMATE PERCENTAGE DISTRIBUTION OF POLLUTANT LOADS

    [%]*
    Non-point sources 95
    Point sources 4
    Aeolian 1
    Total 100
    * Estimated.

J3 SANITARY FACILITIES AND SEWERAGE

  • Percentage of municipal population in the catchment area provided with
    adequate sanitary facilities (on-site treatment systems) or public sewerage: 100%.
  • Percentage of rural population with adequate sanitary facilities (on-site
    treatment systems): 75%.
  • Municipal wastewater treatment systems
    No. of tertiary treatment systems: 0. No. of secondary treatment systems: 20. No. of primary treatment systems: 10.
  • Industrial wastewater treatment systems
    No. of industrial wastewater treatment systems: 19 (oxidation ditches).


L. DEVELOPMENT PLANS (Q)

    A draft water quality management plan for the Upper River Shannon System, including Lough Ree, was completed by An Foras Forbartha in 1986. It provides a quantitative and qualitative assessment of the water resource and identifies the many beneficial uses. Water quality standards and criteria are set out for the maintenance of satisfactory water qualities conditions and remedial measures are listed where necessary. The plan indicates actions necessary for the retention of satisfactory water conditions taking account of projected future development. The specific measures for Lough Ree include an inventory of the phosphorus inputs to the lake, both 'point' and 'non-point' and an assessment of the feasibility of restricting the input of waste-associated phosphorus to the lake. In regard to two smaller lakes (Loughs Coosan and Killinure) connected to the main lake by a narrow channel and known as the 'inner lakes', the policy of the plan is to prohibit any further increase of phosphorus input.


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

M1 NATIONAL AND LOCAL LAWS CONCERNED

  • Names of the laws (the year of legislation)
    1. Local Government (Water Pollution) Act (1977)
    2. Planning Acts (1963-1984)
    3. Fisheries Acts (1959-1980)
  • Responsible authorities
    1. Roscommon County Council
    2. Longford County Council
    3. Westmeath County Council
    4. Shannon Regional Fisheries Board
  • Main items of control
    1. Prohibition of discharges to waters except by licence (sewage discharges excluded).
    2. Control development of land including buildings likely to generate wastes.
    3. Prohibits pollution of fishery waters.

M2 INSTITUTIONAL MEASURES

  1. Roscommon County Council
  2. Longford County Council
  3. Westmeath County Council

M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES

  1. An Foras Forbartha


N. SOURCES OF DATA

  1. Questionnaire was filled by Dr. J. Bowman, the National Institute for Physical Planning and Construction Research, Dublin, based on the data obtained from the following sources.
  2. Charlesworth, J. K. (1963) Proc. Roy. Irish Acad., 63, B. 3.
  3. Whitton, J. B. (1975) Geology and Scenery in Ireland. Penguin.