Heavily Modified Waters in Europe Case Study on the river Lozoya (Tajo, Spain)
Confederación Hidrográfica del Tajo, Calidad de Aguas Agustín de Bethencourt 25, 28071 Madrid phone 34-91-535 05 00, fax 34-91-554 93 00 e-mail: [email protected] Limnos, S.A. Bruc 168 entlo. 2ª, 08037 Barcelona phone 34-93-457 26 54, fax 34-93-458 96 84 e-mail: [email protected]
Table of contents page PART I 6 1 Preface 7 2 Summary Table 8 3 Introduction 10 3.1 Choice of case study 10 3.2 General remarks 10 4 Description of Case Study Area 12 4.1 Geology, topography and hydrology 12 4.2 Socio-Economic Geography and Human Activities in the Catchment 15 4.3 Identification of Water Bodies 17 4.4 Discussion and conclusions 22 PART II 24 5 Physical alterations 25 5.1 Pressures and uses 25 5.2 Physical Alterations 27 5.3 Changes in the Hydromorphological Characteristics of the Water Bodies and Assessment of Resulting Impacts 28 5.4 Discussion and conclusions 30 6 Ecological Status 31 6.1 Biological Quality Elements 32 6.2 Physico-Chemical Elements 38 6.3 Definition of Current Ecological Status 41 6.4 Discussion and conclusions 42 7 Identification and Designation of Water Bodies as Heavily Modified 44 7.1 Necessary Hydromorphological Changes to Achieve Good Ecological Status 44 7.2 Assessment of Other Environmental Options 45 7.3 Designation of Heavily Modified Water Bodies 46 7.4 Discussion and conclusions 47 8 Definition of Maximum Ecological Potential 48 8.1 Determining Maximum Ecological Potential Error! Bookmark not defined. 8.2 Measures for Achieving MEP Error! Bookmark not defined. 8.3 Comparison with Comparable Water Body Error! Bookmark not defined. 8.4 Discussion and conclusions Error! Bookmark not defined. 9 Definition of Good Ecological Potential Error! Bookmark not defined. 9.1 Determination of Good Ecological Potential Error! Bookmark not defined. 9.2 Identification of Measures for Protecting and Enhancing the Ecological QualityError! Bookma 9.2.1 Basic Measures Error! Bookmark not defined. 9.2.2 Supplementary Measures Error! Bookmark not defined. 9.3 Discussion and conclusions Error! Bookmark not defined. PART III 62
2 10 Conclusions, Options and Recommendations 63 10.1 Conclusions 63 10.2 Options and Recommendations 63 11 Bibliography 64 12 List of Annexes 67
______List of Tables, Figures and Maps page Table 1 Geological types in the hydrographical units from the river Lozoya catchment12 Table 2 Soil types in the hydrographical units from the river Lozoya catchment 13 Table 3 General characteristics of the river Lozoya 13 Table 4 Slope in the hydrographical units from the river Lozoya catchment 14 Table 5 Mean precipitation and evapotranspiration in the hydrographical units from the river Lozoya catchment 14 Table 6 Mean discharge during the period 1996-2000 at the gauging station of El Paular and downstream of each dam 15 Table 7 Land uses in the hydrographical units from the river Lozoya catchment 16 Table 8 Population in the river Lozoya catchment 16 Table 9 Relative tourist fluency in the Lozoya catchment villages 16 Table 10.Impacts derived from the economic activities and water uses on the water body and adjacent ecosystems 17 Table 11 Typification of the river Lozoya according to the System A (Annex II de la WFD) 17 Table 12 Identification of stretches along the river Lozoya channel 18 Table 13 Details of the different water bodies groups 21 Table 14 Main characteristics from the river Lozoya reservoirs 25 Table 15 Main characteristics of the canals in the river Lozoya catchment. 26 Table 16 Wastewater treatment plants in the river Lozoya catchment 26 Table 17 Reservoir regulations and delimited areas in the corresponding catchments according to Resource Management Plan of the Lozoya catchment reservoirs 27 Table 18 Location and quantification of the different types of physical alterations along the river Lozoya 28 Table 19 QBR applied to the fluvial segments in the river Lozoya 29 Table 20 Biological Indicators of quality 31 Table 21 Physico-chemical indicators of quality 31
3 Table 22 Most representative genera in the phytoplankton, chlorophyll content (maximum and annual mean) and Secchi disk depth 33 Table 23 Macrophytes, phytobenthos and riverine vegetation in river Lozoya 34 Table 24 Fish fauna in the river Lozoya and main tributaries 35 Table 25 Biological index applied to the benthic fauna found in the river Lozoya 36 Table 26 Benthic organisms in El Atazar reservoir 37 Table 27 Depth of the spillways and discharge intakes of the micro-hydropower stations of the Lozoya river reservoirs 38 Table 28 Contaminants detected in the river Lozoya 39 Table 29 Physico-chemical characteristics of the water in the river Lozoya 39 Table 30 Values of physicochemical and biological quality elements in the river Lozoya 40 Table 31 Ecological status of river Lozoya 41 Table 32 Ecological water regime proposed in the Forestry Plan of the Autonomous Community of Madrid 45 Table 33 River Lozoya reservoirs according Sistem A (WFD Annex II) 48 Table 34 Biological quality elements for lakes 49 Table 35 Hydromorphological quality elements for lakes 49 Table 36 Physico-chemical quality elements for lakes 49 Table 37 Values of some hydromorphological and physico-chemical elements for the river Lozoya reservoirs comparison with Spanish reservoirs. 50 Table 38 Percentaje of reservoirs in four trophic categories. 53 Table 39 Water bodies comparable to the river Lozoya reservoirs (oligotrophic and siliceous) 54 Table 40 Good ecological potential according to physico-chemical and biological quality elements 55 Table 41 Directives and Spanish legislation 58
Annex 1: Maps Map 1. Location of river Lozoya within the river Tajo watershed Map 2. Geology of the river Lozoya watershed Map 3. Topographic map of the river Lozoya catchment (scale 1:200.000) Map 4. River Lozoya network Map 5. Irrigated land in the river Lozoya catchment
4 Map 6. Nature reserves in the river Lozoya catchment Map 7. Population in the river Lozoya catchment Map 8. Water bodies in the river Lozoya relative to the modified characteristics Map 9. Water bodies designed as heavily modified in the river Lozoya Map 10. Location of the water bodies comparable to the river Lozoya reservoirs
Annex 2: Tables Table 1. Monthly discharge, mean annual and median discharge at El Paular gauging station and downstream of each reservoir of the river Lozoya Table 2. Phytoplankton species collected with net in the river Lozoya reservoirs Table 3. Minimum and maximum values of physico-chemical parameters detected at the ICA control stations along the river Lozoya
Annex 3: Figures Figure 1. River Lozoya longitudinal section Figure 2. Temporal variation of discharge and other hydrological parameters in the river Lozoya Figure 3. Population in the main urban areas of the river Lozoya catchment Figure 4. Winter and summer population in small villages located in the river Lozoya catchment Figure 5. Scheme of Canal Isabel II water-works Figure 6. Water rate in the Autonomous Community of Madrid during 1999 Figure 7. Spatial evolution of some physico-chemical parameters along the river Lozoya Figure 8. Spatial evolution of number of taxa, BMWP’ score and ASPT along the river Lozoya Figure 9. Temporal variation of physico-chemical parameters at different ICA control stations along the river Lozoya
5 PART I
6 1 Preface
During the first HMWB meeting held on the 12th of April 2000, Spain accepted to participate in a pilot study on a watershed mainly affected by water supply. This decision was in accordance with the proposal made by the leader States (Germany and United Kingdom) since no other countries were dealing with this water use. After the appropriate consulting, the river Lozoya watershed was chosen because of the series of reservoirs built for water supply to Madrid and surroundings. In this watershed, the enterprise for water supply is Canal de Isabel II, whereas the river authority is the Confederación Hidrográfica del Tajo (CHT).
7 2 Summary Table
Item Units Información
1. Country Spain
2. Name of the case study (name of River Lozoya water body)
3. Steering Committee member(s) Spanish Ministry of Environment (Ministerio de Medio responsible for the case study Ambiente)
4. Institution funding the case study River Tajo water authority (Confederación Hidrográfica del Tajo –CHT-)
5. Institution carrying out the case study CHT / Limnos
6. Start of the work on the case study November 2000
7. Description of pressures & impacts Pressures: Water supply and hydropower. Impacts: expected by impounded river (reservoirs) and regulated river
8. Estimated date for final results August 2001
9. Type of Water (river, lake, AWB, River freshwater)
10. Catchment area km2 983.3
11. Length/Size km 77.7
3 12. Mean discharge/volume m /s 12.34
13. Population in catchment Number 8335
14. Population density Inh./km2 8.48
15. Modifications: Physical Pressures / 5 reservoirs, channelisations, weirs, protected margins / low Agricultural influences impact on watershed from livestock, agriculture, forestry and tourism activities / excessive fishing pressure in headwaters
16. Impacts? Change in river profile, disruption in river continuum and sediment transport, artificial discharge regime and changes in water temperature
17. Problems? Altered biological communities, characteristic of lenitic conditions (in reservoirs) or subjected to artificial discharge and low flows (dowstream the dam)
18. Environmental Pressures? Artificial discharge regime and reduced flow dowstream the dam
19. What actions/alterations are planned? Management of hydraulic flow patterns downstream of each dam. Reduction of eutrophy in reservoirs. Improvement in fish regulations at headwaters
20. Additional Information Good water quality in the river (but eutrophic and mesotrophic
8 reservoirs)
21. What information / data is available? Biological data, water quality data and hydraulic regime data
22. What type of sub-group would you Water supply and, to a lesser extent, hydropower find helpful?
23. Additional Comments Proposed heavily modified water bodies: reservoirs (and downstream regulated river if no ecological discharge regime is achieved)
9 3 Introduction
The water resources of Spain are limited and variable. The rivers of Spain show large fluctuations in discharge. While low order streams are generally dry in summer, they may overflow during autumn storms. Because of the two-edged problem of water scarcity combined with occasional hazardous overabundance, there has always been a need for management of water resources in Spain. To this end, many dams and reservoirs have been built. Some of the oldest reservoirs in the world were built in Spain in the 2nd century, and are still in use. It was after the 19th century, however, when the construction of reservoirs became extensive, and today there are over 1000 of them in use in Spain. These reservoirs are dedicated to a variety of purposes: water supply, irrigation, flood control, and many of them to hydropower generation. The Lozoya river is an example of a river in Spain that has been heavily modified by the construction of a series of reservoirs, serving water supply and hydropower generation uses. Given the large number of reservoirs in Spain and the modifications that they imply in the river segments where they have been built, one of the aspects of the Water Framework Directive (WFD) which most affects our country are the criteria and requirements established for designating water bodies as “heavily modified”, with respect to the environmental objectives which may be established for the same.
3.1 Choice of case study
Within the European working group on HMWB, it was suggested that Spain contribute a case study focusing on a catchment including reservoirs intended for domestic water supply. The Lozoya river was chosen because its path is heavily modified by the presence of a series of reservoirs which are the principal water supply source for the Metropolitan Area of Madrid. These reservoirs are operated by a public company, Canal Isabel II, while the competent water authority for the catchment is the Confederación Hidrográfica del Tajo.
3.2 General remarks
The Lozoya river is a tributary of the Jarama river, which in turn, is a tributary to the right margin of the Tajo river (Annexes: Map 1). The Tajo is the longest river in Spain and the one with the greatest discharge capacity; its reservoirs have a volume of approximately 12000 hm3. The Tajo catchment bears the greatest population-based water demand of all the rivers in the Iberian Peninsula, with over 6 million inhabitants depending on it in Spain alone. The catchment receives markedly unequal contribution from its affluents: those on the right margin, to the north, bringing more than those on the left margin. Within the working group on HMWB, the case studies have been divided among sub- groups according to use and/or type of modifications, yielding a total of 3 sub-groups (meeting of October 10, 2000): • hydropower generation (and water supply);
10 • navegation, urbanization, and flood control; • coastal and transition waters. The case study of the Lozoya river falls into the hydropower sub-group, based on the type of physical modifications affecting it (dams), and because its primary use is water supply and secondary use is hydropower generation. The case study of a catchment dedicated to water supply use such as the Lozoya river provides, was needed to fill in a gap left by the other case studies presented for the European project on HMWB.
11 4 Description of Case Study Area
4.1 Geology, topography and hydrology
Geology The Lozoya river drains primarily from the central mountain range (Sistema Central), which is composed of intrusive and metamorphic rocks, and the Tajo sedimentary trench, a small section just prior to the Lozoya’s confluence with the Jarama (Annexes: Map 2). The greater part of the catchment is composed of gneiss and granite, which implies terrain of low permeability and, consequently, the conductivity of the river waters is very low. Permeable terrains do appear in two sections: in the sub-catchment corresponding to the Pinilla reservoir, with limestone, marls and mesozoic dolomite in the right margin, and gravel and alluvial sands in the left margin. Downstream of La Parra dam, we also find terrain which is permeable due to fissurization (limestone, marls and mesozoic dolomite) and porousity (sands and clayey miocene sands).
Table 1 Geological types in the hydrographical units from the river Lozoya catchment
Hydrographical Area (km2) Geological types (%) units Q P-Q Cc Cd P I Headwaters 39.15 - - - - - 100 Pinilla 209.24 8.61 - 3.16 6.58 - 79.20 Riosequillo 151.48 0.15 - - - - 97.12 Puentes Viejas 273.95 - 1.38 - - 7.76 90.05 El Villar 51.89 - 22.28 - - 6.63 68.18 El Atazar 199.26 - 2.60 - - 44.53 46.14
Q = recent granular not consolidated deposits; P-Q = rañas (not consolidated puddingstone); Cc = karstified carbonate rocks with interbedded marls; Cd = detritic deposits, marls, clayey limestone; P = slate, schist, limestone and other metamorphic rocks; I = igneous and volcanic rocks.
Soils Two main types of soils develop on top of the hard, impermeable substrates (crystaline rocks) which predominate in the Lozoya river catchment: moist brown earth and meridional brown earth. The moist brown earth is found in zones of higher altitude and greater humidity, corresponding to the river source and the highlands of the left margin of the river. The meridional brown earth is found principally in the mid and lower sections of the river, from the exit of Pinilla dam to El Atazar reservoir. In this broad swath of the catchment, and due to the nature of the substrate, surface runoff predominates over infiltration, and consequently, the running water tends to be slightly acid or neutral with few dissolved salts (very low conductivity) but with higher content of suspended solids, especially in periods of heavy rain.
12 The overall homogeneity of the catchment is interrupted only by small areas (near the riverine zone of the Pinilla reservoir and at the river mouth) in which there is a more permeable substrate over which develop small spots of meridional brown earth, rendziniforms and brown earth. In these zones of greater infilitration, there is an ingress of a series of ions such as sulphates, bicarbonates, magnesium and chlorides coming from the solubility of the substrate, which slightly increase the pH and conductivity. Table 2 Soil types in the hydrographical units from the river Lozoya catchment
Hydrographical Area (km2) Soil types (%) units T.M.P. T.P. S/M S/S Headwaters 39.15 - 100 Pinilla 209.24 - 100 Riosequillo 151.48 63.07 36.75 Puentes Viejas 273.95 36.09 63.91 El Villar 51.89 94.87 5.13 El Atazar 199.26 65.95 34.05
T.P.M. S/M = Brown earth on rocks, T.P. S/S = Brown earth on siliceous material
Topography The Lozoya river begins at 2.020 m s.n.m in Puerto de Navacerrada with the name of the “River of the Guarramillas” or “River of Angostura”, and it flows into the Jarama river at 710 m s.n.m (Annexes: Maps 3 and 4). The right margin of the Lozoya river drains the Sierra de Guadarrama which belongs to the Sistema Central, whose highest peak, Peñalara at 2429 m, is located near the source of the Lozoya river. The Somosierra and Sierra del Ayllón ranges with peaks of lesser altitude are located further downstream on the same margin. On the right margin we find spurs of the Sierra de Guadarrama mountains, such as the Sierra de Morcuera and the Sierra de Cabrera. The left margin of the Lozoya river receives the ingress of storm-fed streams, such as the Peñalara river, the Umbría and Artiñuelo streams, De la Puebla river and Riato river. The right margin receives fewer affluents, among them the Aguilón river, Santa Ana stream and the Canencia river. Table 3 Characteristics of the river Lozoya
Surface of the catchment (km2) 983. 3 Type of segment Length (km) Percentage (%) Total river length (km) 77.7 Impounded river 39.0 50.2 Altitude in the river source (m s.n.m.) 2.020 Fluvial segment 38.7 49.8 Altitude in the mouth (m s.n.m.) 710
13 The river has been highly modified by the construction of a series of reservoirs: 50.2 % of the river’s length is taken up by reservoirs, with the result that of the 77.7 km of the total river length, only 38.7 km are fluvial. The path of the Lozoya river is characterized by a steeply sloped headwater section (12-7%); from the small Vadillo reservoir up to the riverine zone of the Pinilla reservoir, the slope decreases (2-1%), while in the regulated sections the slope is less than or equal to 1% (Annexes: Fig. 1). The slopes of the Lozoya river catchment have been calculated according to hydrographic areas, which include the headwaters and the receiving basins of each reservoir of the Lozoya. Steep slopes predominate in all the hydrographic areas (20- 35%) because many affluents on the right margin of the Lozoya river drain the Guadarrama mountain range. Table 4 Slope in the hydrographical units from the river Lozoya catchment
Hydrographical Area (km2) Slope (%) units <3% 3-12% 12-20% 20-35% >35% Headwaters 39.15 - - - 59.26 40.74 Pinilla 209.24 11.93 8.55 5.59 54.52 18.13 Riosequillo 151.48 7.41 9.58 17.57 49.62 13.95 Puentes Viejas 273.95 4.55 12.02 22.17 46.56 13.15 El Villar 51.89 5.04 11.94 24.56 44.48 12.30 El Atazar 199.26 3.97 16.27 21.69 44.16 11.19
Hydrology Rainfall is heavy, especially in the headwaters (annual average of 1395 mm) and decreases progressively towards the confluence with the Jarama river; with an average annual rainfall of less than 700 mm in the hydrographical areas of El Villar and El Atazar. The average annual evapotranspiration presents the opposite pattern, with low values at the headwaters (587.5 mm) and higher values in the lower river section (702 mm). Table 5 Mean precipitation and mean evapotranspiration in the hydrographical units from the river Lozoya catchment
Hydrographical Area (km2) Mean Mean units precipitation evapotranspiration (mm) (mm) Headwaters 39.15 1394.66 587.50 Pinilla 209.24 1072.91 588.79 Riosequillo 151.48 931.49 625.18 Puentes Viejas 273.95 847.97 619.83 El Villar 51.89 657.15 684.12 El Atazar 199.26 697.07 702.09
14 Because the Lozoya is modified specifically by the presence of a series of reservoirs, the variations in its flow may be attributed to the operation of those reservoirs. The gauging station located at the headwaters (El Paular) shows the annual flow variation following the pattern of rainfall, while the fluvial sections downstream of each reservoir show a pattern of highly irregular variation over the last 5 years, with minimum flows of less than 0.5 m3/s. (Annexes: Table 1 and Fig. 2). Table 6 Mean discharge during the period 1996-2000 at the gauging station of El Paular and downstream of each dam
3 Mean discharge (m /s) Q 347 Range
(1996-2000) (1996-2000) El Paular 1.6* 0.1* Pinilla 5.0 0.1-0.2 Riosequillo 6.4 0.0-0.3 Puentes Viejas 9.3 0.0-0.4 El Villar 5.5 0.0-0.3 El Atazar 2.3 0.0
*1994-1996 period It is possible to establish 3 sections of the Lozoya river according to the flow regime: 1) Non-regulated fluvial section: Natural hydrologic regime, rain and snow fed, with broad seasonal fluctuations. Extends from the river source to the riverine zone of the Pinilla reservoir. 2) Regulated fluvial section: Artificial flow regime, affected by the regulation of the Pinilla, Riosequillo, Puentes Viejas and El Villar reservoirs. Extends from Pinilla reservoir to El Atazar reservoir. 3) Final regulated fluvial section. Greatly reduced flow during most of the year, as this section is located at the exit from the last reservoir in the series, from which the majority of the supply water is extracted. Extends from below El Atazar reservoir to the merger with the river Jarama.
4.2 Socio-Economic Geography and Human Activities in the Catchment
Socio-economic geography of the catchment The Lozoya river valley is populated by small villages with traditional cattle raising and forestry activities. The moutainous orography has historically limited agricultural and industrial activities. (Annexes: Map 5). On the other hand, the natural beauty of the landscape and the proximity to Madrid have made the valley a focus for touristic activity. Both the Peñalera Nature Park and the Valle del Paular park are notable centers of tourist attraction. (Annexes: Map 6). Tourist activity is especially heavy in the summer, but there are also tourist activities in the winter related to the ski resort (Valdesquí) just at the source of the Guarramillas river.
15 Table 7 Land uses in the hydrographical units from the river Lozoya catchment
Land uses (km2) Hydrographical Area (km2) Coniferous Hortoculture Intensive and Grazeland, Non- units and broad- land extensive prairies, productive leaved agriculture shrubland land species (reservoirs) Headwaters 39.15 18 - - 21 - Pinilla 209.24 85 14 - 147 3 Riosequillo 151.48 118 15 - 258 7 Puentes Viejas 273.95 199 17 - 447 11 El Villar 51.89 202 17 - 489 18 El Atazar 199.26 237 17 2 637 32
Population in the river Lozoya catchment The estimated total population in the catchment is approximately 8335 inhabitants, which yields a low-density spread of 8.48 inhab/km2. The largest population centers, Rascafría and Buitrago de Lozoya, both with approximate populations of 1404 inhabitants (data from 1998), are located one at the headwater, and the other in the mid valley, respectively (Annexes: Map 7 and Fig. 3). The majority of the urban clusters are located in the left margin from the mid to lower valley of the Lozoya, and have between 1000 to 100 inhabitants. Tiny villages of less than 100 inhabitants are also found along the left margin of the Lozoya catchment, especially along the De la Puebla river and in the margins of El Villar and El Atazar reservoirs. Table 8 Population in the river Lozoya catchment
Stable population Summer increase in population Population in the catchment (inhab.) 8335 Alto Lozoya 34 % Population density (inhab./km2) 8.48 Bajo Lozoya 44 % Lozoya catchment 38 %
In summer, the population practically doubles in the majority of the villages in the valley (Annexes: Fig. 4). The villages with the most tourist activity, however, are found along the upper and mid Lozoya valley, Rascafría being the most often visited (48%), followed by Lozoya (18%), Buitrago de Lozoya (18%), Alameda del Valle (6%), El Paular (5%), Pinilla del Valle (3%) and Lozoyuela (2%). Table 9 Relative tourist fluency in villages from the river Lozoya catchment
The most visited villages % Rascafría 48 Lozoya 18 Buitrago de Lozoya 18 Alameda del Valle 6 El Paular 5 Pinilla del Valle 3 Lozoyuela 2
16 Impacts derived from the economic activities and water uses in the catchment The economic activities and the water uses in the Lozoya river catchment which have an impact on the river, the aquatic and adjacent terrestrial ecosystems are basically (see section 5.1): 1) Water supply and hydropower generation; 2) Livestock, agriculture, and forestry operations; 3) Urbanization and tourism. The impacts of these activites on the aquatic and adjacent ecosystems are summarized in the following table and are described in detail in the following sections. The descriptive parameters used refer to the morphology, quantity, and quality of these ecosystems. Table 10 Impacts derived from the economic activities and water uses on the water body and adjacent aquatic and terrestrial ecosystems.
Economic activities and water uses Water supply and Agriculture, farming Urbanization and hydropower and forestry tourism Morphology Dam, channelisations Cattle fences and Channelisations, weirs, cattle access to river bridges, fords, protected margins, picnic areas, recreational areas, buildings, litter Water quantity Fix water abstraction Temporal and fix water Temporal and fix water abstraction abstraction Water quality Changes in general Increase in water Discharge from conditions turbidity and nutrient wastewater treatment content plants
4.3 Identification of Water Bodies
The Lozoya river may be grossly characterized as a mid-sized river of the Iberic- macaronesian region, high-middle according to the altitude, and siliceous. Table 11 River Lozoya according to system A (Annex II from WFD)
Descriptors River type Ecoregion 2 (Iberic-macaronesian region) Altitude High (2022 m) – Mid-altitude (710 m) Catchment area Medium (983.3 km²) Geology Siliceous
The distinct river stretches encountered along the main river channel of the Lozoya system may be grouped into three water types (Annexes: Map 8): 1) Natural stream: from stretches 1 to 4. 1a) Natural stream: stretch 2 1b) Natural stream with minor physical alterations: stretches 1, 3 and 4.
17 2) Reservoirs: stretch 5 and stretches 7 to 10. 3) Regulated river (regulated river downstream of each dam): stretches 6, 11 and 12. 3a) Regulated river: stretch 6 3b) Final regulated river: stretches 11 and 12.
Table 12 Identification of river stretches in the river Lozoya
Stretch Beginning End Length Slope (%) Description (X/Y coordinates (X/Y coordinates (km) UTM) UTM) 1 04 18 253 / 45 17 708 04 18 619 / 45 18 111 1.5 12.00 Headwaters – skiing resort 2 04 18 619 / 45 18 111 04 25 461 / 45 22 634 8.2 7.07 Presence of river bank vegetation 3 04 25 461 / 45 22 634 04 25 720 / 45 26 080 3.7 2.16 Presence of first signifcant human pressures 4 04 25 720 / 45 26 080 04 31 195 / 45 30 438 6.8 1.18 Opening of river valley 5 04 31 195 / 45 30 438 04 34 943 / 45 33 366 4.4 0.45 Pinilla reservoir 6 04 34 943 / 45 33 366 04 40 800 / 45 33 500 6.4 0.94 Very open valley with some gorges 7 04 40 800 / 45 33 500 04 45 500 / 45 37 400 4.9 0.82 Riosequillo reservoir 8 04 45 500 / 45 37 400 04 52 744 / 45 33 310 9.5 0.63 Puentes Viejas reservoir 9 04 52 744 / 45 33 310 04 52 744 / 45 33 310 7.1 0.56 El Villar reservoir 10 04 52 744 / 45 33 310 04 60 328 / 45 29 162 13.1 0.92 El Atazar reservoir 11 04 60 328 / 45 29 162 04 62 906 / 45 26 113 10.2 0.39 Regulated stretch with bank vegetation occupying river channel 12 04 62 906 / 45 26 113 04 61 740 / 45 25 022 1.9 1.05 Widening of river channel
The following paragraphs broadly describe the river stretches identified which fall into the three groups of water bodies: Stretch 1 (natural stream with minor physical alterations) Small headwater stream that has a discharge of 50-100 l/s, originating in the Navacerrada pass. The main anthropic pressure is from the Valdesquí ski resort which has channelised 250 m of the stream, from the base of the ski lift to the parking lot, with various gauges along the channeled length. Litter, such as plastics, aluminium foil and other anthropic waste from the ski resort may be observed in the streambed. At the end of this stretch there is an abandonned weir. Stretch 2 (natural stream) Mountain stream with no significant anthropic pressures. Clear waters, varied substrate composed of boulders, rocks and cobbles, partially overgrown with mosses and rodophytes. Vegetation of the catchment reaches the riverbank and is composed basically of Pinus sylvestris, Juniperus communis and Quercus pyrenaica. Further along this stretch, truly riparian vegetation begins to develop (presence of Salix and
18 Betula pendula). At the end of this stretch, there is a small dam orginally built for hydropower, but no longer in use. Stretch 3 (natural stream with minor physical alterations) Below the Vadillo dam, there is a small section of well-preserved mountain stream, followed by a slightly modified stretch affected by various human pressures such as: small picnic areas, riverside restaurant parking lots, and pastures which extend to the river. Both the recreational activities and the livestock related activities are the reason for many access paths to the river. There are cattle-grazing pastures on both margins, and in the areas used by cattle there is an abundance of excrement. Truly riparian vegetation in this modified stretch is nearly nonexistent, with the exception of the occasional willow and, on the right margin, a patch of young re-sprouted oak. Stretch 4 (natural stream with minor physical alterations) Human pressures here begin with the Las Presillas recreational area, which consists of a series of weirs constructed by large boulders, and riverbanks also protected by boulders. In this section, the riparian vegetation is replaced by meadows and several recreational structures (small buildings). Below the Las Presillas reservoir, there are areas which are undergoing modification due to the restoration works supported by the Autonomous Community of Madrid (CAM), flood-control measures which consist of creating artificial margins with blocks and stones, and diversion of the natural streambed. Other human pressures observed in this area are the agricultural and livestock activities of the riverside villages (Rascafría, Oteruelo, Alameda and Pinilla), such as cattle farms and pastures that extend to the river. At the end of this section there is a notable increment in the riparian vegetation (Salix, Populus, Fraxinus, Betula) which also extends to the small islets within the streambed itself. Stretch 5 (reservoir) The Pinilla reservoir is the first of the series of reservoirs that provide water supply to the Autonomous Community of Madrid. The catchment of this reservoir includes a large amount of livestock activities. There are many cattle pastures, combined with scattered oak groves. There is a wastewater treatment plant (Pinilla del Valle) which discharges into the left margin of the reservoir. Stretch 6 (regulated river) Below the Pinilla reservoir, the stream flows into open valley, which narrows in a few points to gorges, such as the Roman bridge or Hoya Encavera. The flow here is heavily modified and depends on the water discharged from the upstream reservoir and the hydropower plant at Pinilla. The riparian vegetation here is well-developed (Fraxinus, Salix) including even some gallery structures. The human activities affecting this catchment consist of extensive livestock operations with pasturelands, la Dehesa de Lozoya on the right margin and la Dehesa de Mata Aguda on the left margin, which have limited the potential vegetation growth (Quercus spp.). Stretch 7 (reservoir) The Riosequillo reservoir catchment is populated with Quercus ilex and Quercus coccinea. A line of willows grows along the reservoir margin. The human pressure in
19 this catchment consists of residential areas such as “El Verdugal” and a few scattered houses. The impact of livestock is less notable here than in the previous stretches, however there are hoofprints and excrement left by livestock in the accesses to the edge of the reservoir. Stretch 8 (reservoir) In the vegetation of the catchment of the Puentes Viejas reservoir, holm-oaks (Quercus rotundifolia) and planted pine forest (Pinus pinaster) dominate. At the riverine zone of the reservoir, there is a sub-section with well-devloped riparian vegetation (poplar, willow and ash) but the hydrologic regimen is artificial and depends on the discharge from the dam and hydropower station of Riosequillo. The human pressures in this catchment basically derive from one of the main population centers of the Lozoya catchment, Buitrago de Lozoya, which discharges effluent from its wastewater treatment plant into the reservoir, and has 12th century fortification walls forming a protected riverbank in the Buitrago meander. Stretch 9 (reservoir) El Villar reservoir is affected by human pressures consisting basically of an old out-of- use dam (El Tenebroso) located at the riverine zone of the reservoir, protected reservoir banks, and water channelisations. El Villar reservoir catchment is similar to that of the previous reservoir (Puentes Viejas), with low scrub, some pasture, disperse stands of Quercus rotundifolia and planted Pinus pinaster. At the start of this stretch, just below the Puentes Viejas dam, the riparian vegetation is well-developed (mainly Salix with some Populus), but the hydrologic regime is heavily modified by the dam. Stretch 10 (reservoir) El Atazar reservoir suffers drastic variations in water level, as it is the last in the series of reservoirs supplying water to the Autonomous Community of Madrid. The erroded margins denuded of vegetation that can be observed when the water is at low level is one effect of these shifts in level. This catchment has very few inhabitants and trees are scarce; the right margin has a few planted pines and there are some isolated holm oaks on both margins. The shrubs vegetation consists of rockrose, juniper, and mountain genistae, and there are a few areas of mountain grass. Stretch 11 (final regulated river) This stretch corresponds to the water discharged from El Atazar dam, with a limited to non-existent flow during most of the year, and consequently, riparian vegetation occupies even the central part of the channel. There are cliffs along the banks that are as steep as 60-70 % grade en some sections. Vegetation growth in the catchment consists of low-growing thickets and a few, isolated holm-oaks and maples. In some sub-sections, especially towards the end, the riparian vegetation disappears, yielding to meadows and grassland. All along this stretch there are man-made retaining walls reinforcing the river banks. There is also a small dam (La Parra) and at the very end of this unit, the out-of-use Pontón de la Oliva reservoir where the effects of visiting livestock are evident in the eutrophization (increase in algae covering the rocks) and turbidity of the water. Stretch 12 (final regulated river)
20 This unit begins downstream of the Pontón de la Oliva reservoir. The riverbed widens here, the substrate changes to predominately gravel and sand, and the water is more turbid than in the preceding stretch. Anthropic debris (plastics) may also be observed in the riverbed.
Table 13 Details on groups of water bodies
Name of the Main pressures of the Main physical alterations of Water bodies Section group group the group of the group referring to the group Natural None None Stretch 2 Part II stream Minor physical alterations Channelisation, weirs, Stretch 1 Part II (tourist resort) protected margins Stretch 3 Stretch 4 Reservoir Water supply and Change in river profile Stretch 5 Part II Hydropower Disruption in river continuum Stretch 7 (dams) and sediment transport Stretch 8 (dams) Stretch 9 Stretch 10 Artificial discharge regime Direct disturbance to fauna/flora Regulated Regulated river Disruption in river continuum Stretch 6 Part II river downstream of each dam and sediment transport Stretch 11 Artificial discharge regime and Stretch 12 reduced flow in the river bed Direct disturbance to fauna/flora Alteration of thermal regime
21 4.4 Discussion and conclusions
The main issues considered important in identifying the water bodies The water bodies have been identified according to parameters defining their natural qualities and the anthropic modifications to which they have been subject. The basic diagonistic parameters used refer to hydromorphology, water quality, and biological conditions. The use of these parameters as tools for evaluating the general conditions of each water body is developed further in Annex V of the WFD, and broadly speaking, allows us to distinguish the headwaters, a steeply inclined section with a thick substrate and very clear water, from the calmer middle section, with muddier water influenced by the contributions of the catchment. However, in the case of the Lozoya, the various infrastructures and water uses have been the factor bearing the greatest weight in defining the water bodies. All along the streambed there are channelisations, fortified riverbanks, weirs and dams, which result in water bodies of varios tipes. The linear constructions in the streambed change the hydromorphological characteristics, causing accelerated flows and alterations in the streambed and banks. The dams and weirs have an even stronger impact, as they eliminate the fluvial system; the pools they create occupy riparian zones, and at the river bottom, silt replaces the rocky substrate formerly in balance with the current. In these water bodies, the cycles of stratification and mixing, combined with the plankton metabolism (which can be more or less intense according to the degree of trophism) can lead to significant modifications in water quality. The type of water use, in this case predominately for water supply although there is some hydropower production as well, is the third most important factor to bear in mind in identifying these water bodies. The fluctuations in water level of the reservoirs have a significant impact on the reservoir margins, causing the surface to remain devoid of vegetation. Additionally, the changes in regulated flow and the physio-chemical quality of the water below the reservoirs also result in new ecological conditions to which the river communities must adapt. The combinations of the factors described have made it possible to place the water bodies along the Lozoya channnel into four basic types. At the headwaters, a section of natural stream followed by another slightly modified stream, both with predominately fluvial characteristics. In the middle section, large reservoirs alternating with short stretches of regulated flow. Main problems experienced in identifying the water bodies Overall, the criteria established for identification of the water bodies turned out to have great practical value. Perhaps the most problematic point would be the interfaces, especially when these show sigificant changes over time and space. Two examples may serve to illustrate: 1) in the sequential reservoirs, where the stream immediately below a reservoir may be temporaily included in the impounded areas of the following reservoir; and 2) the sections of regulated flow where it is not easy to ascertain objectively the degree to which the imbalance in the regulated hydric regime differs from the natural hydric regime. For the purposes of this case study, we have always
22 opted for the highest degree of transformation, such that we have considered to be regulated stream all sections with modified hydric regime, and have considered to be reservoir all the area included between a dam and the maximum level of its pool. Comments on the level of differentiation The methodology applied has permitted a highly detailed degree of differentiation: 12 distinct stretches (Table 12) in 78 km of river, grouped into three water bodies (Table 13). This result has been possible because the river chosen for case study has undergone a high level of intervention, resulting in a diversified typology. Based on the field work, the stretches identified have a minimum length of 1.9 km, and a maximum of 13.1 km. Therefore, this river with <1000 km2 of catchment has been divided into stretches of approximately 1 – 10 km. In any case, the length of each stretch depends exclusively on the importance of the modification produced by human pressure.
23 PART II
24 5 Physical alterations
5.1 Pressures and uses
Water supply and hydropower production The primary economic and social force responsible for creating significant human pressure on the Lozoya river is the drinking water supply use of its reservoirs. (Annexes: Fig. 5) The oldest of the reservoirs in the Lozoya river catchment is the Pontón de la Oliva reservoir, built in 1855. It is operated by the public company Canal Isabel II, a consortium which has been supplying water to Madrid since 1851, and nowadays to all of the Autonomous Community of Madrid. Reservoirs from the Lozoya river provide nearly 50% of the total water supplied to the Madrid Autonomous Community. The total capacity of the 5 reservoirs is approximately 589 Hm3, with El Atazar reservoir having the largest single capacity of 425.3 Hm3. Table 14 Main characteristics from the river Lozoya reservoirs
Dam Year in service Volume (hm3) Area (ha) Height (m) Power (kW) Pinilla 1967 38.1 480 33 2320 Riosequillo 1958 50.0 326 56 7200 Puentes Viejas 1939 53.0 280 66 7200 El Villar 1879 22.4 144 50 5680 El Atazar 1972 425.3 1070 134 8640
Canal Isabel II later took advantage of the dams and chutes of the five reservoirs to construct five hydropower plants which began operation between 1992 and 1995. The total generated power potential is approximately 31040 kW, a modest but significant contribution to the electric energy needs of the Community of Madrid. In order to blend in better with the local landscape, some of these hydropower plants have been set into the mountain (to build the El Villar plant the mountain was cut into 64 m vertically, and for El Atazar plant, the vertical cut was 34 m) so that the machinery could be housed in the mountain at water level. The current operation for supplying water to the Community of Madrid consists of diverting water from all 5 reservoirs, from the first (Pinilla) through the last (El Atazar). At the start of winter, water is accumulated in the reservoirs and is released throughout the summer until minimums are reached in the autumn. This pattern of filling and emptying the reservoirs follows the water consumption pattern of the Community of Madrid (Annexes: Fig. 6), which rests at approximately 40 hm3 per month during most of the year, but which peaks in summer with a maximum demand in July of 56.3 hm3 (data from Canal de Isabel II for 1999). Of the total water supplied to the Community, 42.3 % proceeds from the Lozoya river catchment. There are three canals which distribute the water to the metropolis, with a flow capacity ranging from 3 to 16 m3/s.
25 Table 15 Canals main characteristics in the river Lozoya catchment.
Canal charateristics El Villar Canal El Atazar Canal La Parra Canal In service since 1912 1966-70 1904 Length (km) 16.7 65.4 23.7 Flow capacity (m3/s) 8 16 3 Beginning El Villar dam El Atazar dam La Parra weir End Depósito Superior Depósito de Pza. Canal Bajo (tank) Castilla (tank)
Agriculture and forestry The economic activities traditionally carried out in the catchment are basically livestock operations and conifer plantations, which both have little impact on the aquatic systems and their adjacent areas in the Lozoya catchment. In addition, the orography does not favor agriculture, and this has limited the appearance of eutrophization processes which can result from the use of fertilizers. Urbanization and tourism The pressure of urbanization has had a low impact on the fluvial ecosystem in the Lozoya catchment. On the one hand, since there are neither large urban or industrial centers, the quantity of contaminant discharge is very small, and on the other hand, a large effort has been directed towards wastewater treatment (“Wastewater Treatment Plan for the Community of Madrid 1995-2005/Plan de Saneamiento y Depuración de Aguas residuales de la Comunidad de Madrid 1995-2005”) because the existing population centers are located on the banks of reservoirs which supply water to the Autonomous Community of Madrid. Currenty there are five wastewater treatment plants in the entire catchment, three of which are suburban and two are local. In order to reduce eutrophization of the reservoirs, the suburban wastewater treatment plants eliminate phosporous and nitrogen. The treatment achieves a reduction of nutrients of approximately 90% of total phosphorus and 50% of total nitrogen. In addition, the treatment is sufficiently flexible to adapt to the large variations in flow and contaminant load produced by the summer population increase. Table 16 Wastewater treatment plants in the river Lozoya catchment.
Type of wastewater Wastewater Municipalities treated Nutrients removed treatment plant treatment plant Suburban Pinilla Rascafría, Alameda del Valle Phosphorus Lozoya Oteruelo Riosequillo Canencia Phosphorus and Nitrogen Garganta de Montes Gargantilla del Valle Puentes Viejas Buitrago de Lozoya Phosphorus Villavieja del Lozoya Local Cervera Cervera de Buitrago - El Berrueco El Berrueco -
26 The Master Plan for Wastewater Treatment (Plan Director de Saneamiento y Depuración del 100% de los Municipios de la Autonomous Community of Madrid) allows for inclusion of all towns with fewer than 2000 inhabitants, which presently do not have appropriate wastewater treatment procedures, in the future. Another pressure noted in the catchment is that of tourism. The Lozoya catchment is a popular tourist destination because of its proximity to Madrid. In summer, the population increases sharply (see Section 4.2). Throughout the rest of the year there is a continual flow of local tourists during the weekends and on holidays; the winter period brings an influx of skiers as well. Because this catchment is designated as a water supply source for the Autonomous Community of Madrid, there is a Resource Management Plan for each one of its reservoirs, which limits and regulates the acitivities permitted within the receiving catchments of the reservoirs as well as in the reservoirs themselves. Table 17 Reservoir regulations and delimited areas in the corresponding catchments according to Resource Management Plan of the Lozoya catchment reservoirs
Regulated activities in the reservoirs Areas Regulated fishing and hunting Maximum protection areas Swimming forbiden Areas to protect Boats and nautical sports forbiden (except in Areas to regenerate the El Atazar reservoir) Traditional livestock areas Fire forbiden Traditional farming areas Plant, animal and mineral collection forbiden Urban areas Recreational areas
5.2 Physical Alterations
The pressures and uses described in Section 5.1 result in a series of physical impacts on the water bed, the banks and the riparian zone of the Lozoya river. These impacts may be divided into two types: • Alterations to the river channel or bed: channelisations (photo 1), dams (photo 2), weirs (photo 3), bridges (photo 4), blockades (photo 5), cattle fences (photo 6) and advance of riparian vegetation (photo 7). • Indirect and direct alterations to the riparian zone or the banks of the river: flood breaks (photo 8) and protected banks (with rocks, boulders, cement and/or concrete), picnic areas (photo 9), recreation areas (photo 10), structures (photo 11) and presence of debris (photo 12). The following table shows all the impacts noted along the entire length of the river, including the streambed itself and the margin area as well.
27 Table 18 Type and number of physical alterations in the water bed and banks along the river Lozoya
Physical alterations Stretch Place Type 123456789101112Total river bed channelisations 31112- - -3 1 3 1 16 dam -1- -1-112 1 1 - 8 weir 1122----- 1 1 1 9 bridge -357-5-31 1 1 2 28 ford -1-1------2 cattle fence --3------3 advance of riparian vegetation ------3 - 3 subtotal 69 margins protected banks --47------11 picnic areas ---2------2 recreation areas ---2----- 2 - - 4 structures/buildings 1122----2 - 2 - 10 presence of debris ------2- - 3 - 5 subtotal 32 total 101
5.3 Changes in the Hydromorphological Characteristics of the Water Bodies and Assessment of Resulting Impacts
The most notable hydromorphological changes in the Lozoya catchment result from the creation of the reservoirs. The use and operation of the reservoirs results in changes both in the water level of the reservoirs themselves and in the hydric regime downstream of the dam. The following list details the resultant hydromorphological and physical changes: • Reservoirs: − Creation of impounded water bodies: change from a river to lacustrine environment. − Accumulation of sediment in the reservoir bottom: change from a rocky substrate in accordance with the erosive, sedimentary and transport forces of a river, to a substrate of primarily fine particle sediment. − Disruption in river continuum: fragmentation of the river system. − Disruption in sediment transport: changes in the streambed morphology (overexcavation and granulometric shift). − Artificial flow regime: changes in the riparian vegetation and the bank morphology, changes from the truly fluvial biological communities (phytobentos, benthic invertebrates and fish) • Reservoir use and operation: − Fluctuations in the level of the impounded water body as a result of the reservoir operation: erosion of the margins and formation of denuded surfaces. − Hydromorphological changes downstream of the dams.
28 Assessment of resulting impacts The impacts of these hydromorphological changes can be evaluated in the riparian zone of the segments without reservoirs according to the QBR index (Munné et al., 1998), which takes into account the following elements of the riparian habitat in which riparian vegetation could potentially develop: 1) Total riparian cover 2) Cover structure 3) Quality cover 4) Channel alteration Table 19 QBR index applied to the water bodies identified in the river Lozoya
Water bodies QBR index Alterations Quality Natural stream 90-85 Some disturbance Good (from headwaters to Pinilla reservoir inlet) Regulated river 60 Considerable disturbance Fair (from Pinilla dam to El Atazar dam) Final regulated river 65-40 Considerable disturbance / Fair / Poor (downstream of El Atazar dam) Strong alteration
Riparian habitat quality level: >90 = riparian habitat in natural condition, high quality; 75-90 = some disturbance, good quality; 55-70 = considerable disturbance, fair quality; 30-50 = strong alteration, poor quality; 0-25 = extreme degradation, very poor quality. The quality of the banks is good in the fluvial sections from the headwaters to the riverine zone of the Pinilla reservoir, becoming notably poorer in the final section of regulated flow. • Natural stream. The degree of riparian vegetation cover in this upper middle section of the river varies between 50% to 80%, maintaining the connection with adjacent forest ecosystems (pine woods and thickets). The riparian vegetation contains an elevated percentage of native tree species (birch, poplar, ash), the shores being partially overhung by stands of black willows. The morphology of the streambed appears to be unchanged except in very specific areas (the Las Presillas recreation area). • Regulated river. Downstream of the reservoirs, the elimination of ordinary flooding has resulted in the modification of the lower river terraces, reducing the fluvial channel. The quality of the banks with respect to vegetation is moderate. • Final regulated river. The riparian vegetation cover and the river morphology are modified by the reduced flow, showing development of a dens alder-forest in some sections. The quality of the banks is moderate and, in some sections, deficient.
29 5.4 Discussion and conclusions
Lessons learned The pressures and uses with the greatest impact on the Lozoya river are primarily related to supplying water to a large metropolitan area (Madrid) and, to a lesser degree, related to hydropower generation. Practically all the modifications observed, including changes to morphology and to the hydrologic regime, stem from the mentioned activities. The other pressures are of little importance. The agricultural and forestry operations and the resident human population hardly alter the river at all, either because their effects do not reach the river or because appropriate preventative measures have been taken (wastewater treatment with tertiary systems in urban areas). The physical alterations can affect the streambed, the banks or both. In the case of hydraulic infrastructures, 16 canals, 8 dams and 9 weirs were counted. Among infrastructures affecting the banks, we observed 8 lateral reinforcements. Other infrastructures such as bridges, crossings, cattle fences, picnic areas, small buildings, and garbage bins have a much smaller impact. The quality of the riparian vegetation is highly dependent on the structural integrity of the streambed. The quality also reflects the human pressures on it, as the vegetation must compete with human activities (agriculture, access to the river). According to the field study evidence, in all the non-impounded sections of the river there is riparian vegetation. The riparian habitat has good quality at headwaters and is being progressively altered downstream; the condition is fair in the intermediate sections of regulated river, and fair-to-poor closer to the merger with the Jarama. Problems encountered and how they were overcome The main problem determining the physical alterations is the presence of shortfalls in the availability of information. The relevant Water Authorities and the License Operators know the infrastructures under their control in detail, however there are numberless modifications that have never been documented or which have been forgotten. To bring the information up to date would require an exhaustive field survey, such as the one performed for this project, based on a reconnaissance of the entire river and its margins, including mapping of all the modifications observed.
30 6 Ecological Status
The ecological status of the river Lozoya water bodies has been classified according to the physico-chemical and biological quality elements (WFD Annex V, 1.1. “Quality Elements for the Classification of Ecological Status”) which are listed in the two following Tables. Table 20 Biological Quality Elements
Biological quality elements Water body type Reservoir River Phytoplankton + Other aquatic flora (macrophytes + + and phytobenthos) Macroinvertebrates + + Fish fauna + +
The data available for each biological quality community is described below: • Phytoplankton: samples taken in the present study (November 2000), data from Canal Isabel II and from the CAM (1997). • Macrophytes and phytobenthos: field observations and samples taken in the present study and earlier data from García de Jalón (1979), Casado (1986) and the Forestry Plan from the CAM. • Macroinvertebrates: samples taken from the river in the present study, and earlier data from García de Jalón (1979), Casado (1986) and Martín (1997), data on benthos in reservoirs from Real (1993). • Fish fauna: García de Jalón (1992) and Confederación Hidrográfica del Tajo (1998). Table 21 Physico-chemical quality elements
Physico-chemical quality Water body type indicators Reservoir River General conditions: Transparency + Thermal conditions + + Oxygenation + + Mineralization + + pH + + Nutrients + + Specific contaminants + +
The data available for the physico-chemical quality elements are described below: • Data on transparency, temperature, oxygen, conductivity and ammonium measured in the present study (November 2000). • Data on general conditions and specific contaminants from the ICA stations of the CH Tajo (1994-2000).
31 6.1 Biological Quality Elements
This section describes the ecological quality of each water body according to the biological quality elements, including as well the following aspects for each biological community (phytoplankton, other aquatic flora, macro-invertebrates and fish): 1) Availability of information: Information not provided by the existing data Need for data and additional measures proposed 2) Indicative function of the organisms: To what degree are the impacts on biological communities derived from physical modifications? Are the organisms themselves good indicators of those impacts? Description of the impacts upstream and downstream of the physical modification Are there other significant modifications (such as pollution)? How can such pressures be separated?
Composition, abundance and biomass of phytoplankton The creation of impounded water bodies permits the development of plankton communities. The limited capacity of the reservoirs (low retention time), with the exception of El Atazar reservoir, conditions the development of phytoplankton in the sense that it is less abundant and the community is less mature. Given the density and dominance of species found (Annexes: Table 2), the five reservoirs may be classified as moderately eutrophic (Pinilla, Riosequillo and El Atazar) and eutrophic (Puentes Viejas and El Villar). Pinilla. The phytoplankton is sparse and shows little diversity. The diatom Melosira granulata and the chlorophyt Pediastrum duplex predominate, while other species (mainly diatoms) are found with minimum density. The dominant species are indicators of moderately eutrophic non-stratified waters (mixing season). Ríosequillo. The phytoplankton is sparse, mainly composed of diatoms, among which Melosira granulata and Fragilaria crotonensis predominate. Both species are characteristic of the mixing season in moderately eutrophic waters. Puentes Viejas. The phytoplankton, of moderate density, consists of species indicative of eutrophic waters. Worthy of mention is the dominant, potentially toxic, cianophytes Aphanizomenon gracile accompanied by the diatoms Melosira granulata and Fragilaria crotonensis. El Villar. Phytoplankton almost exclusively consists of the diatom Melosira granulata, the density is high and typical of eutrophic reservoirs of low-mineralization. El Atazar. Phytoplankton almost exclusively consists of the cianophytes Oscillatoria rubescens with high density. This species is typical of moderately eutrophic waters of
32 low-mineralization. On occasion, the density of the phytoplankton is such that it lends a reddish tint to the water.
Table 22 Most representative genera in the phytoplankton, chlorophyll content (maximum and annual mean) and Secchi disk depth
Reservoir Mixing period Stratification Max. Mean Secchi Disk period chlorophyll chlorophyll (m) (µg/l) (µg/l) Pinilla Asterionella Aphanizomenon 50.3a 10.7a 2.1ª Fragilaria Anabaena 1.4c Melosira Staurastrum Pediastrum Riosequillo Ceratium - - 7.6b 3.0b Fragilaria 2.6c Melosira Puentes Viejas Aphanizomenon - - 16b 4.0b Fragilaria 3.9c Melosira El Villar Ceratium - 26.3a 6.6a 3.5ª Fragilaria 3.4c Melosira El Atazar Asterionella Ceratium 18.3a 2.8a 5.3ª Fragilaria 2.7c Melosira Oscilatoria adata from 1989-96 period (Canal Isabel II), bdata from july 1997 (“Additional depuration required in susceptible areas / Necesidades de complementación de depuración en zonas sensibles” by the CAM); cdata from november 2000 (present study). The Canal Isabel II company performs a routine monitoring of the phytoplankton in the reservoirs from which water is diverted directly for water supply use (Pinilla, El Villar and El Atazar), as part of the water supply quality control. They identify the predominant species and the chlorophyl concentration as an indirect measure of the relative abundance of phytoplankton. With respect to shortfalls in data, the information from Canal Isabel II, ought to be more routinely passed on to the relevant water authority (Confederación Hidrográfica del Tajo). As a biological parameter, the phytoplankton are highly suitable for determining the trophic state of the reservoir, and therefore, reflect the changes in use of the catchment and the pressures from pollution. They also reflect the hydric regime to which the reservoir is subject, for example, a low density of phytoplankton and a low concentration may be indicative of high frequency of water renewal.
Composition, abundance of macrophytes and phytobenthos The phytobenthos and especially the macrophytes in the Lozoya river are good indicators of the changes in flow below each reservoir.
33 • Natural stream. The headwaters segment is characterized by scarce to non- existant riparian vegetation cover, which allows the development of incrusting phytobenthos (briophytes, rodophytes, incrusting chlorophytes and diatoms) on the boulders and rocks of the streambed. • Regulated river. Below each dam it is possible to observe the effects of the fluctuations in the discharge level, such as growth of grasses and ruderal plants which are periodically flooded. The strong, sudden fluctuations in flow have resulted in the reduction or elimination of the natural vegetation below each dam. Due to the same cause, the shores of the reservoirs themselves show very scarce vegetation, and in most cases are completely deforested. • Final regulated river. This segment has a macrophyte community (Myriophillum verticillatum and Ceratophyllum demersum) indicative of stagnant or slow-moving waters. Table 23 Macrophytes, phytobenthos and riverine vegetation in river Lozoya
Water bodies Riverine vegetation Macrophytes and phytobenthos Natural stream Grasses: Gramineae Bryophyta (from headwaters to Pinilla Shrubs: Genista, Salix Rhodophyta reservoir inlet) Trees: Pinus sylvestris, Quercus pyrenaica Chlorophyta (crustose) Diatoms Regulated river Grasses: Gramineae (Potamogeton pectinatus) (from Pinilla dam to El Atazar Shrubs: Carex fusca, Scirpus, Salix Ranunculus aquatilis dam) salviifolia, Salix atrocinera, Rubus ulmifolius, Rosa canina, Phragmites Trees: Populus nigra, Populus tremula Final regulated river Grasses: Gramineae Bryophyta (downstream of El Atazar dam) Shrubs: Carex fusca, Scirpus, Salix (Potamogeton pectinatus) salviifolia, Salix alba, Juncus Ranunculus aquatilis Trees: Populus nigra, Alnus glutinosa, Ceratophyllum demersum Fraxinus angustifolia Myriophillum verticillatum
Data from the present study and the Forestry Plan from the CAM; species found in Casado (1986) but not in these two other studies are between brackets.
Fish Fauna The Table below lists the species found along the course of the Lozoya river and in two of the affluents to the Lozoya catchment.
34 Table 24 Fish fauna in river Lozoya and main tributaries.
River Tributaries Family Species Lozoya Canencia Madarquillos Authochthonous Salmonidae Salmo trutta + species Cyprinidae Barbus bocagei ++ Chondrostoma polypepis + Leuciscus alburnoides ++ Leuciscus pyrenaicus ++ + Rutilus arcasii ++ Cobitidae Cobitis calderoni ++ Cobitis paludica ++ + Allochthonous Cyprinidae Carassius auratus ++ species Cyprinus carpio + Gobio gobio ++ Tinca tinca + Centrarchidae Lepomis gibbosus + Total number of species 13 7 3
• Natural stream. Trout is the only species found in the upper segments, headwaters and upper headwaters of the Lozoya river catchment. These trout populations are characterized by mid-to-high relative density, especially in the closed sections. From the middle section of the Lozoya river (El Paular) onward, the trout populations are characterized by extremely low densities and by being accompanied by abundant ciprinid populations. The current status of the trout populations is determined by a excessive fishing pressure, accompanied by an inadequate minimum capture size. • Regulated river. The fish fauna below the reservoirs is poor due to the strong oscillations in water lever and the low minimum flow. • Reservoirs. Introduced species (red carp, carp, gudgeon, tench, and sun perch) are found in the reservoirs. In the first reservoir of the series, Pinilla reservoir, the fish community is rich, including both the typical species of the river segments as well as the introduced species.
Macroinvertebrates The benthic composition depends on the hydromorphological characteristics and the type of substrate dominant in each section of river.
35 Table 25 Biological index applied to the benthic fauna found in river Lozoya.
Water bodies No. of taxa BMWP’ ASPT’ Water quality (maximum) (maximum) (maximum) level (maximum) Natural stream I’: Very clean (from headwaters to Pinilla reservoir inlet) 27 170 7 waters
Regulated river III: Hydrological (from Pinilla dam to El Atazar dam) 11 42 2.8 alteration or pollution
Final regulated river I’: Very clean (downstream of El Atazar dam) 30 162 5.4 waters
• Natural stream. The species found in this first segment are characteristic of mountain streams, with cold, very clear, oxygenated waters. The great variety of species of Plecoptera, Tricoptera and Ephemeroptera reflects the heterogeneity of habitats, composed of boulders, gravel, sand, mosses growing on rocks, oak leaves accumulated between rocks and trunks, etc. The number of taxons is high (maximum of 27) and the biotic index also (maximum of 170). • Regulated river. The type of substrate found downstream of the dams changes significantly with respect to the segments of natural stream; the proportion of sand and silt increases, and the water is more turbid. The number of taxons is low (maximum of 11) and the biotic indices (maximum of 42) indicate that the community reflects a modified or heavily modified water body. • Final regulated river. The flow in this segment proceeds mostly from the affluents. The contribution of water from the Lozoya river, which is restrained by El Atazar, the last reservoir of the series, is almost nil. The reduced flow, of natural water regime, maintains a rich community of taxons (maximum 30) and a very high biotic index (maximum 162). The invertebrate community is mid-alpine with some of the species characteristic of waters that are lentic or moderate current lentic environments or moderate flow (and with vegetation), such as Odonata (very well represented, both in number of species and abundance) and Ephemeroptera of the Cloeon genus. There are abundant Hydropsyche, a genus of tricopter which proliferates in rocky streambeds that carry suspended particles, from which the Hydropsyche feeds via filtration. There is only one genus of Plecoptera (Leuctra), which tolerates a moderate level of pollution. Among the crustaceans we find Atyaephyra desmarestii, a species indicative of waters of slightly increased mineralization. • Reservoirs. The bottoms of the reservoirs only allow development of benthic fauna typical to fine sediment substrates. Available data are for the bottom of El Atazar reservoir at 92 m depth, in the winter of 1988 (Real, 1993). The invertebrate fauna consisted basically of oligochaetes (Tubificidae) accompanied
36 by benthic cladocerans (Ilyocriptus sordidus), both resistent to low levels of oxygen. Table 26 Benthic organisms in El Atazar reservoir.
Benthic organisms (ind/m2) El Atazar Oligochaetes (Tubificidae) 2675 Chironomids 100 Cladocerans (Ilyocriptus sordidus) 25 Nematodes 25
Shortfalls in data and recommendation for further sampling. The macroinvertebrates are the biological community which best reflect the impact of modifications to the hydromorphological characteristics of the river channel. The Lozoya river is not included in the biological monitoring network established by the Spain’s Ministry of the Environment in 1998 for the Tajo river catchment. The authors propose adding the following sampling points to the monitoring network: 1) Upstream from Alameda del Valle (representative of natural stream); 2) Exit from the Pinilla reservoir (representative of a regulated segment); 3) Downstream of the Pontón de la Oliva dam (representative of the final regulated segment). Temporal evolution. A comparison of the studies on the benthic fauna performed from 1979 to the present shows a progressive impoverishment and simplification of the Lozoya river fauna. Both effects are reflected in the loss of species, affected by the regulation and in the replacement of native species with more generalist and cosmopolitan species (Martín, 1997). Longitudinal evolution. The communities of the three sectors into which the river is divided in this study (Table 25) also show that the gradient of the river’s longitudinal continuity has been interrupted. The majority of the species of a given sector are exclusive to that sector, and the species that are common to all sectors are banal components that exist in any water body (Martín, 1997). Alterations due to pollution. The quality of the Lozoya water river is generally good (see Section 6.2); on the one hand, no specific contaminants were detected, and on the other, the general conditions are good/very good except in the reservoirs (meso- eutrophic conditions). In the last two stretches of the river (stretches 11 and 12) before it merges with the Jarama, two types of impacts of little effect converge: nutrient enrichment, due to the agriculture and livestock activities in the catchment, and the reduction of the river flow. The biological communities reflect these two alterations; showing development of macrophytes and invertebrates that are tolerant to a limited degree of eutrophy, and to stagnant or limited current waters.
37 6.2 Physico-Chemical Elements
Impacts of the physico-chemical alterations on the physico-chemical characteristics The reservoirs impose a series of physical modifications that distort the physico- chemical characteristics of the waters, both in the reservoir itself and in the fluvial segments below the dams. Reservoirs • Stratification of the water: formation of a thermocline between 5 and 6 m, except in El Atazar where it is located somewhat deeper (10 m). • Night-day and seasonal changes in pH: the maximums are reached during the hours and periods (summer) of most sunlight and are always related to the photosynthetic action of the primary producers. • Oxygenation conditions: hypersaturation of the illuminated zone, cause by the primary production, and hypoxia or anoxia (as a result of the organic load, both alochthonous and autochthonous) in the hypolimnion during the stratification season, with the exception of El Atazar, which maintains good oxygenation conditions throughout the year. Downstream segments The reservoirs of the Lozoya River discharge their waters to the river via bottom drains and via the waters released from the hydropower stations. The released waters generally correspond to the hypolimnion waters with physical and chemical characteristics different from those of the surface waters. The following Table shows the depths of the drains and the outlets of the hydropower stations. Table 27 Depth of the spillways and discharge intakes of the micro- hydropower stations of the river Lozoya reservoirs
Pinilla Riosequillo Puentes Viejas El Villar El Atazar Dam height (m) 33 56 66 50 134 Spillways high - 25 17 - - (Depth in m) medium - - 33 7 79 low 21 37 45 43 108 Discharge intakes high 4 - 14 12 - (depth in m) medium - - 27 22 - low 13 - 42 34 -
The consequences of discharging from the reservoir bottoms into the fluvial segments below the dam are: • Homogenisation of the water temperature. • Increase in the nutrient concentration (ammonium) and in total suspended solids. • Decrease in the concentration of dissolved oxygen.
38 The reservoirs act as both accumulators and dissipaters of heat, and therefore, along the course of the river there is a homogenization of the water temperatures and a reduction of the annual and inter-annual thermal fluctuations. In the summer and fall, due to the thermal stratification, the water discharged is cooler than would correspond to a river in equilibrium with the atmosphere, and in contrast, in the winter the water discharged is more temperate. The reservoirs also behave as exporters of nutrients (especially ammonium) and of suspended solids (Martín, 1997). The maximum discharges including from the Pinilla to the El Villar, are in winter and spring, when the river flow is highest, and the water is transferred from Pinilla to El Atazar (where it accumulates). In the segments below these dams which discharge water, except for the dam of El Atazar, an increase in fine and ultra-fine particulate organic material is observed (Casado, 1989). This load tends to disappear along the course of the river because the chain of reservoirs acts as a series of settling ponds (data from 1993-94 from Martín, 1997).
39 Impacts of the pollution on the physico-chemical characteristics The activities related to agricultural and livestock operations, urbanization, and tourism are the only activities in the catchment which may have some effect on the physico- chemical characteristics of the Lozoya river water. The main contaminants on the list in Annex VIII of the WFD, do not currently exceed the ecological quality limits established by the CH Tajo for the Tajo river (A-2). These limits have been occasionally exceeded in the past at the following gauging stations and for the following parameters (Annexes: Tables 3 to 8 and Fig. 9). Table 28 Contaminants detected in river Lozoya.
Rascafría Pinilla Riosequillo Puentes El Villar El Atazar Viejas Contaminants (ICA 52) (ICA 53) (ICA 55) (ICA 56) (ICA 57) (ICA 58) Phosphate (mg/L) - 0.81 - - 0.73 - (year 1997) (year 1998) Suspended matter (mg/l) - 32 - 66 - - (year 1998) (year 1997) Copper (mg/L) - 0.06-0.11 - 0.07 0.09 - (year 1994) (year 1994) (year 1999) Manganese (mg/L) - - - - 0.16 0.73 (year 1996) (year 1996) Total coliforms (100 130.000 1010 1.4*1010 - - - cells/ml) (year 1998) (year 1995) (year 1994) 42.000 (year 1998)
The total coliform values reflect some influence of wastewater at the end of the upper section (Rascafría and Pinilla) and in the middle section (Riosequillo). On the other hand, both the wastewater and the agriculture and livestock operations can contribute phosphates (elevated concentration in Pinilla) and an increase in total suspended solids in the reservoirs (phytoplankton biomass). The increase in the concentration of manganese may be the result of its release in the hypolimnetic anoxic waters. In addition to the data from the CH Tajo, data are available for temperature, conductivity and ammonium concentration as measured in situ during the reconnaissance of the river (Annexes: Fig. 7). In these data one may observe the following: • Slight increase in ammonium in the sections where there are agriculture and livestock operations and large villages near the shores, especially at the end of the first section of natural stream. • Slight decrease in ammonium along the series of reservoirs due to the self- purifying capacity of the reservoirs: at the entrance of the Pinilla reservoir, the concentration of ammonium detected is the highest in the entire course of the Lozoya river (0.3 mg/L) while at the El Atazar dam, it has descended to 0.1 mg/L. • Increase in conductivity along the course of the river, which in the case of the final segment below the El Atazar dam is due to the river passing through an area of soluble substrate at that point. Table 29 Physico-chemical characteristics of the water in the river Lozoya.
40 River segment Temperature Conductivity (µS/cm) Ammonium (ªC) (mg/L) Non-regulated river segment beginning 5 14.6 <0.05 (from de headwater Pinilla reservoir entrance) end 6.4 65 0.2
Reservoirs and regulated river beginning 6.1 104 0.3 segments (from Pinilla dam to El Atazar dam) end 10.8 97 0.1
Final regulated segment beginning 9.8 206 0.07 (downstream of El Atazar reservoir) end 12.3 239 0.1
6.3 Definition of Current Ecological Status
The ecological status, as defined by the WFD, is “an expression of the quality of the structure and functioning of aquatic ecosystems associated with surface waters”. Expert criteria have been applied in the assessment of each of the biological and chemical quality elements. With respect to the macro-invertebrate communities, these criteria have been combined with a biotic index (BMWP’), adapted to the Iberian Peninsula and widely used. Table 30 Values of physico-chemical and biological quality elements in the river Lozoya.
Physico-chemical elements Biological elements Water bodies General Specific Macrophytes Benthic Fish fauna conditions pollutants and invertebrate phytobenthos fauna Natural stream (headwaters to High / Good High High High Good Pinilla reservoir inlet)
Regulated river (from Pinilla Good High Poor Moderate / Poor dam to El Atazar dam) Bad
Reservoirs Moderate High Bad Bad Bad
Final regulated river Good High Moderate Good Poor (downstream of El Atazar dam)
For each group of quality elements (biological or physico-chemical) the resulting classification is a subjective weighing of the values of each of its elements (Table 31) Next, the two groups of quality elements have been combined considering the classification of the ecological status and ecological potential as described in Annex V of the WFD: “...the ecological status classification for the body of water shall be respresented by the lower of the values for the biological and physico-chemical monitoring results...” (Table 31).
41 Table 31 Current ecological status of the river Lozoya
Water bodies Physico-chemical Biological quality Ecological status quality indicators indicators Natural stream (from High / good High High / good headwaters to Pinilla reservoir inlet)
Regulated river (from Pinilla Good Poor Poor dam to El Atazar dam)
Reservoirs Good Bad Bad
Final regulated river Good Moderate Moderate (downstream of El Atazar dam)
6.4 Discussion and conclusions
Lessons learned The biological quality elements included in the WFD have an indisputable value for diagnosis of ecological status. The most significant physical alterations, which are the dams and weirs, create a new environment upstream which drastically influences the biological community and the consequences of which can be assessed through the changes in the phytoplankton, the aquatic flora, the macroinvertebrates, and the fish. The impounding of the water encourages the development of plankton, and its quality and quantity depend on the regional physico-chemical parameters of the water (mineralization and temperature), the rate of turnover, and the nutrient concentration. As for physical alterations, the development of plankton attributable to hydrological changes make it possible to discern to what degree the fluvial characteristics have been modified. The nutrients would enter following the favourable synergy of plankton development in the conceptual framework of eutrophization. The fluvial benthos disappears and is replaced by very poor communities made up of organisms adapted to living in silt. The aquatic vegetation also becomes notably scarce, with only a few species characteristic of lenitic waters remaining. The fish communities also suffer major alterations due to the changes in habitat and because these changes favor the introduction of new, better-adapted species which unbalance the local fauna. Downstream, in the regulated segments, the benthos, the vegetation and the fish continue to be good indicators of alterations. The alterations may be characterized by hydrological changes, which result from reduction of the flow, the regulation or inversion of the hydrological and thermal cycles. In any case, the complex web of the river biology suffers as all the organisms are eliminated that have their cycles tied to the natural hydrological events. The more resistant species tend to remain, in many cases coinciding with polluted waters.
42 It is easy to distinguish the response of organisms to effects of physical alterations from effects from other possible causes. In general, the changes observed are quite evident, as they have to do with changes in the habitat. The biological changes produced by other alterations such as pollution or depredation have a greater reversibility. The lineal physical alterations, such as canals and flood-works have a lesser impact, as they change only part of the habitat, and in any case, have an extension of several orders of magnitude less. The organisms that suffer are basically the zoobenthos and the aquatic vegetation, which respond with a decrease in the biodiversity by simplification of the spatial heterogeneity. The effects of the physical alterations on the physico-chemical quality of the water show in the temperature (lower than normal in summer) and possibly the dissolved oxygen in the water drained from the reservoirs during the most eutrophic episodes. By evaluating the various parameters it has been possible to establish that high and good ecological status is found only in the natural stream at the headwaters. The other water bodies of the river merit an inferior rating due to the biological indicators, especially in the case of the reservoirs, for which the qualification is bad, and the regulated river, for which qualification ranges from moderate to poor. Problems encountered and how they were overcome. The definition of the ecological status requires a good knowledge of the physico- chemical and biological characteristics of the water bodies. In general, information on these characteristics is either not available, or only partial information is available, as the indicators which the WFD requires to be used, are quite complex. In addition to the large number of indicators involved, it is necessary to consider their variation in space and time. Fortunately, the Lozoya has been the subject of numerous studies, which has made it possible to have sufficient information to perform the diagnostics. Furthermore, the diagnostics have benefited from data obtained through a reconnaissance of the entire river by expert biologists, which has made it possible to fill in for any lacking information and to confer uniformity on the previously existing information. The weaknesses of the definition of ecological status according to the WFD are: • The subjective nature of the assessment if based on expert criteria. Some investigators propose using biotic indices (Prat & Munné, 2000) which are simple to use, obtained rapidly, and require little economic investment. • It is still necessary to define how the different results for each of the indicators are to be combined. One option would be to give higher importance to a specific group of organisms in the case of biological indicators; but which is more important: the macroinvertebrate community, the aquatic vegetation, or the fish fauna? For purposes of this study this point has been resolved by applying a subjective weight to the values obtained for each biological group.
43 7 Identification and Designation of Water Bodies as Heavily Modified
7.1 Necessary Hydromorphological Changes to Achieve Good Ecological Status
This section describes the changes in the hydromorphological characteristics that would be (theoretically) necessary in order to achieve a good ecological status in the sections of regulated river between the reservoirs. An estimate and evaluation is also provided of the effects these changes would produce on the uses described earlier (see Section 5.1 and Art. 4.3 (a) 1). The steps to follow may be summarised in the following four questions: 1) How have the required measures to achieve good ecological status been defined? 2) How has the impact of these measures on water uses been described? 3) How have “significant adverse effects” been defined (tools may range from simple descriptions of the consequences to economic analysis)? 2 4) How have impacts upon the wider environment been assessed? Reservoirs. The efforts for achieving a good ecological status should focus on the mitigation measures which will improve the quality of the biological indicators, which presently have an unacceptable rating, in contrast to the good condition indicated by the chemical indicators. The creation of the reservoirs has completely changed the characteristics of the habitat, especially with respect to the benthic and fish fauna. The existing benthic communities in the reservoirs are characteristic of fine sediment, and in the case of fish, their communities are of limited quality with many introduced species (see Section 6.1). In order to achieve a good ecological status, it would be necessary to reverse the lenitic conditions to lothic conditions, which implies elimination of the dams. Such measures would have considerable negative repercussions on the current water uses, especially that of water supply to the Autonomous Community of Madrid. The hydropower use is less important, since it amounts to mini hydropower stations with
1 Article 4.3 (a) WFD. ”Member States may designate a body of surface water as artificial or heavily modified when: (a) the changes to the hydromorphological characteristics of that body which would be necessary for achieving good ecological status would have significant adverse effects on [Uses]: i) the wider environment, ii) navigation, including port facilities, or recreation, iii) activities for the purposes of which water is stored, such as drinking water supply, power generation, irrigation, iv) water regulation, flood protection, land drainage; or v) other equally important sustainable human development activities.” 2 Different methods for decision-making are: - rule of thumb - expert assessment (incl. qualitative and quantitative data) - direct consideration of ”main” or dominant uses, involving political decision, public involvement and consensus among water users.
44 limited production (31.040 kW installed potential and 105 GW/h forecast annual production). Regulated river segments downstream of reservoirs. As in the case of the reservoirs, here also the efforts for achieving good ecological status should focus on mitigation measures that will improve the quality of the biological indicators, which currently have a rating of poor to moderate, in contrast to the good conditions indicated by the chemical indicators. Downstream of the dams, the communities are characteristic of lothic, but heavily modified environments (see Section 6.1). In order to achieve a good ecological status it would be necessary for all these sections to have a hydric regime, which allows macrophytes, invertebrates and fish to thrive. These measures have been defined according to the ecologic flow requirements for maintaining an optimal icthyofauna biomass (applying Bovee’s method –PHABSIM, Physical Habitat Simulation-) of native species (trout). Table 32 Ecological water regime proposed in the Forestry Plan of the Autonomous Community of Madrid.
Water body Ecological Percentage of Water flow Remarks water regime the actual distribution along water flow the year Regulated river Trout stretch 34 % 2.3 m3/s from mid-July With a further increase (between Pinilla that requires 59 to mid September, in water flow (>2.3 m3/s) dam and Hm3/year and from November to there is no significant Riosequillo dam) mid February increase in fish biomass 1.5 m3/s the rest of the year Final regulated Trout stretch 12 % 1.5 m3/s from mid-July With a further increase river (downstream that requires 29 to mid September, in water flow (> 1.5 of El Atazar dam) Hm3/year and from November to m3/s) there is a slight mid February increase in fish biomass 0.3 m3/s the rest of the year
7.2 Assessment of Other Environmental Options
Identification and definition of the beneficial objectives served by the modified characteristics of the water body [Art. 4.3 (b)] 3 As described earlier in Section 5.1, the main use of the reservoirs in the Lozoya catchment is that of water supply to the Autonomous Community of Madrid. The chain of reservoirs in the Lozoya is part of a system of 14 reservoirs, all located in tributaries of the Tajo river (Jarama, Alberche, Guadalix, Sorbe and Manzanares), which provide water to 138 municipalities and a total of 4,811,077 inhabitants.
3 Article 4.3 (b) WFD. ”Member States may designate [...] as heavily modified, when: (b) the beneficial objectives served by the [...] modified characteristics of the water body can not, for reasons of technical feasibility or disproportionate costs, reasonably be achieved by other means, which are a significantly better environmental option.”
45 The construction of dams in the Lozoya river catchment since 1855 to provide water supply to Madrid has historically conferred a series of benefits on the populations served. The Autonomous Community of Madrid benefits by an almost unique natural water resource within the Spanish context. The most significant natural contributions within the Tajo catchment correspond to the Lozoya river. It is a catchment with a high annual contribution (385.45 hm3) due to a high precipitation level (more than 1000 mm at the Lozoya river headwaters). The chemical quality of the water is also good: on the one hand, the river water is soft because it passes over a substrate composed of impermeable materials (granites and Paleozoic slates), and on the other, there is little impact from direct and/or diffuse pollution in the water (see Section 5.1). The hydraulic infrastructures consist of an extensive system of canals, conduits and deposits, which are presently very well cared for, and used profitably (hydropower stations at the dams). Other alternative to the existing “water use” [Art. 4.3 (b)]. It is difficult to imagine alternatives for the water supply to the Autonomous Community of Madrid which would be technically feasible; not disproportionately costly; and which would reasonably achieve significantly better environmental option. In the hypothetical case that it were possible to extract water from other catchments (via diversions, construction of other dams in other catchments, etc.), destroying the existing dams to reverse the heavily modified conditions is not feasible. The environmental consequences would be extremely negative, among which we might number: • Impacts from the dam demolition works on the aquatic and adjacent ecosystems; • Drastically altered reservoir bottom for which reversion to the original conditions is extremely difficult. The only possible alternative would be management of reservoirs so that the regulated sections below each dam could maintain good biological conditions starting with the ecological flows indicated in Table 32.
7.3 Designation of Heavily Modified Water Bodies
The water bodies designated as heavily modified are (Annexes: Map 9): • The reservoirs • The fluvial segments downstream of each reservoir (in the case that it is not possible to regulate the flow in order to maintain good biological conditions) It is possible to take two approaches to the process of designation, which are described below.
46 Designation of heavily modified water bodies based on physical alterations. According to this process of designation, in the Lozoya only the dam and the regulated fluvial section downstream of the dam could be considered heavily modified water bodies. But it is not possible to apply this approach in the Lozoya river because the dam (physical modification) also affects the ecological conditions upstream (impounded waters, completely different conditions from the fluvial ones). The valid option for designation that has been used in this study is the following. Designation of heavily modified water bodies based on hydromorphological alterations. The designation of the heavily modified water body includes the dam, the reservoir created above the dam, and the regulated fluvial section below the dam. All this area is affected because of the dam (physical modification) and is designated as heavily modified. The hydromorphology is altered both upstream and downstream of the dam, which affects the ecological status.
7.4 Discussion and conclusions
Lessions learned The nature of the physical alterations and the water uses in the Lozoya river catchment lead to the designation of the reservoirs as heavily modified water bodies. There are no alternatives to the water supply use and a return to original conditions is not feasible. The regulated sections downstream of the reservoirs also merit designation as heavily modified water bodies, although alternatives could be considered for guaranteeing maintenance of an ecological water regime. That could be consider as a flow rate associated to a good ecological potential. Problems encountered and how they were overcome In the case of the Lozoya, it is possible to propose the alternatives of considering only the reservoirs or only the sections of river below the dams as heavily modified water bodies. Although in this study, the authors have chosen to apply Article 4(3) of heavily modified water bodies to the reservoirs, one may consider the possibility that these enter in Article 4(5) since they meet the requirements specified therein, and therefore, the reservoirs. In this last case the water bodies would be treated with less stringent environmental objectives.
47 8 Definition of Maximum Ecological Potential
48 8 Definition of Maximum Ecological Potential
The maximum ecological potential is the set of reference conditions for the water bodies designated as heavily modified according to the current uses. To achieve the maximum ecological potential, mitigation measures have to be taken to ensure: • Hydromorphological conditions that are the best approximation to ecological continuum, in particular with respect to: − Migration of fauna − Appropriate spawning and breeding grounds for aquatic flora and fauna • Physico-chemical elements that correspond totally or nearly totally to the undisturbed conditions For the establishment of reference conditions the following steps are undertaken: 1) Characterisation of the heavily modified water bodies According to WFD Annex II 1.1(v) “For artificial and heavily modified surface water bodies the differentiation shall be undertaken in accordance with the descriptors for whichever of the surface water categories most closely resembles the heavily modified or artificial water body concerned”. In the river Lozoya watershed, descriptors of lakes are applied to its reservoirs. Reservoirs have generally been considered synonymous with lakes and are classified as lake type 73 (Hutchinson, 1957). The approach to many reservoir limnological studies is identical to the approach used in many lake studies, and the response exhibited by a reservoir is interpreted within the context of conventional wisdom of lake limnology. 2) “Lake” types The river Lozoya reservoirs may be grossly characterised (according to System A) as: high “Lakes” (≥ 880 m of altitude); of medium size (1-5 km2 of water surface area); of intermediate depth (Pinilla) or deep (the rest); with siliceous geology and belonging to ecoregion 2 (Iberic-Macaronesian); with the exception of El Atazar which has high-mid altitude (880-760 m of altitude) and is large (>10 km2 of water surface area). Table 33 River Lozoya reservoirs typified according to System A (WFD Annex II)
Descriptors Pinilla Riosequillo Puentes El Villar El Atazar Viejas Ecoregion 2 (Iberic- 2 2 2 2 Macaronesian) Altitude High High High High High –mid altitude (1100-1080 m) (1020-980 m) (980-920 m) (920-880 m) (880-760 m) Mean depth Intermediate Deep Deep Deep Deep (8.8 m) (15.8 m) (18.7 m) (16.3 m) (42 m) Surface area Medium Medium Medium Medium Large (4.8 km²) (3.3 km²) (2.8 km²) (1.4 km²) (10.7 km²) Geology Siliceous Siliceous Siliceous Siliceous Siliceous
49 3) Quality elements As lakes are the most closely surface water category that resembles the river Lozoya reservoirs, the biological, hydromorphological and physico-chemical quality elements for lakes are given in the following tables (WFD Annex V 1.1.2). Table 34 Biological quality elements for lakes
Biological quality elements Composition, abundance and biomass of phytoplankton Composition and abundance of macrophytes and phytobentos Composition and abundance of benthic invertebrate fauna Composition, abundance and age structure of fish fauna
Table 35 Hydromorphological quality elements for lakes
Hydromorphological quality elements Hydrological regime: quantity and dynamics of water flow residence time connection to the groundwater body Morphological conditions: depth variation quantity, structure and substrate structure and condition of the shore
Table 36 Physico-chemical quality elements for lakes
Physico-chemical quality elements General conditions: transparency thermal conditions oxygenation conditions salinity acidification status nutrient concentrations Specific pollutants
4) Reference conditions for each of the quality elements In Spain there are no large lakes; nevertheless, there is a great number of small lakes and lagoons, mainly located in the Pyrenees and in other mountain ranges (Sierra Nevada, for example). The only two largest lakes are Lake Sanabria (glacial lake) and Lake Banyoles (karstic lake). Spain is the Member State with the highest number of reservoirs (over 1,000), from which 100 have been extensively studied in two periods (1973/75 and 1987/88) to establish a regional limnology. Consequently, reference conditions have to be based not only on lake studies but also and mainly on reservoir studies (Margalef et al. 1976, Riera et al. 1990). In both studies, types of reservoirs were established according to water ionic composition (Armengol et al. 1991) and trophic status (Morguí, 1991). Firstly, Spanish reservoirs were classified into four groups attending to the total dissolved solids content and the relatively ionic composition of their waters. According to this
50 classification, river Lozoya reservoirs belong to group I, which includes those reservoirs of low water mineral content and alkalinity ≤ 1meq/L, and are located in the eastern siliceous zone of the Iberian Peninsula. According to WDF System A, river Lozoya reservoirs have been classified as siliceous. Furthermore, Spanish reservoirs were classified into 4 groups of increasing trophic status (oligotrophic, meso-eutrophic, eutrophic and hypereutrophic) according to total reactive phosphorus content and chlorophyll a content in epilimnetic waters. All reservoirs in the river Lozoya are mesotrophic with the exception of Pinilla, which is eutrophic. Values for several hydromorphological and physicochemical quality indicators of the river Lozoya reservoirs are presented in the following Table and are compared with Spanish reservoir ranges (Margalef et al. 1976, Riera et al. 1990). Table 37 Values for some hydromorphological and physico-chemical elements of the river Lozoya reservoirs in comparison with the range in Spanish reservoirs
Range in Pinilla Riosequillo Puentes El Villar El Atazar Spanish Viejas reservoirs Hydromorphological quality elements Residence time 0.00078 (min.) 0.05 0.04 0.02 0.01 0.21 (years) 8.87 (max.) 2.70 3.44 90.89 3.29 111.91 Physico-chemical quality elements Transparency 0.18-7.79 (win.) 1.4b 2.6b 3.9b 3.4b 2.7b (m) 0.11-8.6 (sum.) Temperature 6 –13 (win.) 3.3 4.7 6.7 4.0 6.0 (ºC) 17-27 (sum.) 23.3 23.8 24.3 23.0 24.6 Conductivity Ic 20-175 62-115 57-84 56-94 46-107 61-98 (µS/cm) c 2- 2- 2- 2- 2- 2- Major anions I CO3 CO3 CO3 CO3 CO3 CO3 Na + K : Ca + Mg Ic <1 0.13-0.27 0.39-0.84 0.45-0.47 0.43 0.18-0.28 Total reactive 0.001-25 ≤0.08a ≤0.05a ≤0.05a ≤0.05a ≤0.05a phosphorus (mg/L) Trohic status* Oligotrophic - Eutrophic Mesotrophic Mesotrophic Mesotrophic Mesotrophic Hypereutrophic aData from ICA sampling stations (surface waters near the dam) in 2000; bData obtained on November 2000 in this study; *According to OCDE criteria; CFor conductivity, major anions and Na+K:Ca+Mg ratio, the range for the group I is given from the classification of Spanish reservoirs in four groups according to the total dissolved solids and ionic composition (Armengol et al., 1991). The rest of the data corresponds to minimum and maximum values detected during 1994-2000 in the ICA sampling stations.
51 8.1 Determining Maximum Ecological Potential
Reference conditions for each of quality elements (hydromorphological, biological and physico-chemical) are described below taking into account the following environmental constraints: high-mid altitude (cold waters) and with low conductivity waters (group I according to ionic composition). Biological quality elements Phytoplankton. The optimal phytoplanktonic community should correspond to that of oligotrophic and siliceous reservoirs (Margalef, 1976; group A in Sabater & Nolla, 1991) with diatom species such as Melosira (Aulacoseira) distans and Tabellaria flocculosa; and desmidiaceae such as Cosmarium depressum, Spondylosium planum, Staurastrum gracile and S. mesikomerii. Phytoplanktonic densities should be low (≤100 cells/ml). Macrophytes. If hydromorphological conditions should enable the establishment of a macrophyte reference community, this should be composed of submerged macrophytes that thrive in stagnant areas in the fluvial sections of river Lozoya: Ranunculus aquatilis, Ceratophyllum demersum and Myriophillum verticillatum. Macrophyte species associated with the reservoir littoral zone should be Carex fusca, Scirpus, Juncus and Phragmites, which nowadays are only present on the river banks of the regulated fluvial sections of the Lozoya. Benthic invertebrate fauna. The profundal benthic reference community (invertebrates that inhabit fine sediments) should be composed of species characteristic of cold, low conductivity and oligotrophic waters, the last gives good oxygenation conditions in the hypolimnion and, therefore, in the sediment. Furthermore, in oligotrophic reservoirs, there is less phytoplanktonic density and therefore, less autochthonous organic matter supply to the sediment, which favours the presence of microcarnivorous (Tanypodinae chironomids) and detritivorous taxa (oligochaetes). Chironomid genera characteristic of cold, low conductivity and oligo-mesotrophic waters are: Sergentia, Micropsectra and Tanytarsus. Oligochaeta species characteristic of the same environmental conditions are: Stylodrilus heringianus –oligotrophic indicator species-, Spirosperma velutinus – cold water stenotherm species-, Spirosperma ferox and Aulodrilus pluriseta. The maximum annual density of benthic organisms should be relatively high (> 20,000 ind/m2, in oligotrophic reservoirs from the river Duero watershed, 1989). Fish fauna. Reference fish community in these reservoirs should be composed mainly of salmonids (Salmo trutta) and cyprinids such as Chondrostoma polypelis, Leuciscus pyrenaicus and Rutilus arcasii, accompanied by low densities of Barbus bocagei. This fish community should be characteristic of cold waters with a high oxygen content. In Spain there are no fish species characteristic of standing waters because natural lakes are scarce and sparse. Therefore, the above mentioned species are characteristic of fluvial environments that colonise reservoirs. These species feed on benthic organisms and consequently any mitigation measure that should enhance the presence of littoral zone vegetation should provide suitable habitats and food for the fish community.
52 Hydromorphological quality elements To achieve ecological continuity and allow undisturbed migration of aquatic fauna and presence of suitable habitats for the aquatic flora and fauna, reference conditions for this quality element group should be: Hydrological regime. Outflows and reservoir operation should minimise water level fluctuations in order to achieve an optimal littoral zone structure so as to enhance the development of littoral vegetation and submerged macrophytes. Morphological conditions. Reservoirs should have a progressive longitudinal sedimentary gradient from headwater to dam (without excessive silting): coarse particles in the delta and riverine zone, sands in the transition zone, and silt and clay in the lacustrine zone. Shores should have irregularities such as embayments, sand and fine gravel beaches, etc. Physico-chemical quality elements The Lozoya reservoirs with only very minor anthropogenic alterations should achieve oligotrophic status, with mean annual low chlorophyll content (<2 mg/m3) and low phosphorus content (<0.01 mg/L), according to classification criteria based on trophic status of Spanish reservoirs (Morguí, 1991) and ranges established by the OCDE. With low nutrient content and therefore low phytoplankton biomass, oxygenation conditions should be good in the water column. Furthermore, Secchi disk depth (water transparency indicator) should be greater than 6 m.
8.2 Measures for Achieving MEP
To reach the maximum ecological potential it would be necessary to undertake measures in order to improve: 1) hydromorphological quality 2) physico-chemical quality of the water The achievement of these potential environmental conditions would allow the development of reference biological communities described in Section 8.1. Measures to improve the hydromorphological quality • To achieve minimum water level fluctuations compatible with the current water supply • Creation of wetlands in the riverine zone of reservoirs • Regeneration of the littoral zone (achieving continuity with the terrestrial ecosystems), by means of biological engineering techniques, based on the use of vegetal materials as part of the constructive process. • To achieve ecological continuum with respect to migration of fauna (elevators and stairs for fishes)
53 Measures to improve physico-chemical water quality To diminish the trophic status in Lozoya reservoirs up to oligotrophic conditions, the mitigation measures should focus on the reduction of phosphorus and nitrogen loadings from diffuse source and point source discharges: • Diffuse source: − Control over agricultural and farming activities − Creation of wetlands • Point source discharges: − Construction of wastewater treatment plants in tributaries
8.3 Comparison with Comparable Water Body
As mentioned at the beginning of this chapter, the most comparable water bodies to the Lozoya reservoirs have to be other Spanish reservoirs as they have been built in greatest profusion in Spain where natural lakes are scarce. To determine reference conditions, physicochemical quality elements (mineral water content and nutrient conditions) and hydromorphological (most frequent lacustrine environments in Spain) have been considered. The reference reservoirs most comparable to the Lozoya reservoirs are those oligotrophic ones with siliceous waters. According to three recent studies, there are a few oligotrophic reservoirs in Spain (Table 38) and they represent between 7 and 28 %. This variability depends on the systems studied and time periods considered; during dry periods the percentage of eutrophic reservoirs increases while during humid periods this percentage diminishes. Table 38 Classification of Spanish reservoirs into four trophic categories according to three recent studies
Trophic status (%) Alvarez-Cobelas et al. (1992) Armengol & García (1997) Avilés et al. (1997) Oligotrophic 7 28 26 Mesotrophic 23 22 34 Eutrophic 51 41 33 Hypereutrophic 19 9 7
Within the category of oligotrophic and siliceous reservoirs, three comparable reservoirs to the river Lozoya reservoirs have been chosen, due to similar morphometric and altitudinal characteristics (according to System A): • Cernadilla (river Tera) would be comparable to El Atazar according to the morphometric characteristics (deep and with large water surface area) and altitudinal range. • Camporredondo and Compuerto (river Carrión) and El Vado (river Jarama), with a smaller water surface area, but relatively deep, would be comparable to Riosequillo, Puentes Viejas and El Villar.
54 Table 39 Water bodies comparable to the river Lozoya reservoirs (oligotrophic and siliceous)
Watershed Altitude (m) Mean depth (m) Surface (river) (km2) Reservoirs Camporredondoa Duero (Carrión) 1290 18.0 3.9 Compuertoa Duero (Carrión) 1221 25.3 3.8 El Vadob Tajo (Jarama) 924 19.0 3.0 Cernadillaa Duero (Tera) 889 17.6 14.5 Lakes Sanabria Tera* 1000 35.0 3.2 aoligotrophic according to data from Junta de Castilla y León (1989); boligotrohic according to data from Cedex (1989) but mesotrophic according to Morguí (1991); *main tributary. Similarity of physico-chemical and morphological characteristics favours the comparison of ecological conditions between these water bodies and the river Lozoya reservoirs. Furthermore, geographical proximity (biogeographical constraints) with the river Lozoya watershed facilitates the comparison of biological communities (Map 10): − El Vado reservoir is within the same hydrographic watershed (Jarama, Tajo) − The other reservoirs are located in a neighbouring watershed (Duero) Lake Sanabria (glacial origin) might also be considered as a water body comparable to the Lozoya reservoirs as it is oligotrophic (1.5-18 µg/L of PRS and 5-15 m disk Secchi depth) and has siliceous (conductivity range of 13-18 µS/cm) and cold waters (4-20ºC of temperature). Moreover, morphometric characteristics (mean depth of 35 m) and altitude (1000 m) are similar to those of the river Lozoya reservoirs. Lakes of glacial origin are those most comparable water bodies to reservoirs as they have a frontal moraine, which is comparable to a dam, and moreover, have fluctuating water level (for instance, Lake Baña in León). Nevertheless, the water outlet is located at the surface as opposed to the majority of reservoirs, whose outlets are located at high or intermediate depths.
8.4 Discussion and conclusions
Lessons learned With the current available information on reservoirs from regional studies (or local), reference conditions of the maximum ecological potential for the Lozoya reservoirs have been identified. Nevertheless, in the near future more research based on Spanish and Portuguese basins will be necessary for both the regionalization of water bodies and the establishment of reference conditions. In the description of reference conditions for each of the biological quality indicators, the present study have used taxonomic composition, nevertheless, more accurate data on densities, biomass and age structure -for fishes- would be necessary. Information on indicator species characteristics has been used.
55 Problems encountered and how they were overcome For the definition of ecotypes in the regionalization studies, the WFD proposes the use of System A or System B. In this study, System A has been used as it has well defined classes and fewer descriptors. In regionalisation studies within the same basin, System B would be recommended, but this arises two questions: which descriptors have to be included and how they can be synthesised. For this purpose, ordination and classification methods of selected environmental variables (hydrological, geological, morphometric and climatic) should be used as has already been done by Prat and Munné (2000) in the river Ebro watershed. In the Lozoya reservoirs, the appropriate level of mitigation that should ensure the best approximation to ecological continuum should be the minimisation of water level fluctuations. Lake Sanabria represents the best approximation to constant water level that allows the development of littoral zone vegetation and therefore, continuity with the terrestrial adjacent terrestrial ecosystems.
56 9 Definition of Good Ecological Potential
9.1 Determination of Good Ecological Potential
The determination of good ecological potential in the river Lozoya reservoirs depends on the viability of the mitigation measures (feasible and reasonable measures to reach the good ecological status and therefore comply with WFD). These measures would reduce the trophic status of the reservoirs: (i) from eutrophic to mesotrophic (Pinilla), and (ii) from mesotrophic to oligotrophic (El Atazar), as it is the last in the multiple- reservoir series, in which nutrients are progressively being trapped. The rest (Riosequillo, Puentes Viejas, El Villar), with the reduction of the trophic status, would remain within the mesotrophic category but without anoxia in the hypolimnion. Table 40 Good ecological potential according to physico-chemical and biological quality elements
Physico- Biological quality elements chemical quality elements General Phytoplankton Macrophytes Benthic Fish fauna conditions and invertebrate specific pollutants fauna Pinilla, Riosequillo, Mesotrophic Community of - Community of Community of Puentes Viejas, El conditions cold, siliceous cold, siliceous cold, siliceous Villar (without anoxia in and and and the hypolimnion) mesotrophic mesotrophic mesotrophic waters waters waters El Atazar Oligotrophic Reference - Reference Reference conditions community community community (described in (Section 8.1) (Section 8.1) (Section 8.1) Section 8.1)
The “slight deviations” from the maximum ecological potential for the values of each biological quality indicator are defined below with regards to each water body. Biological quality elements Phytoplankton. The phytoplanktonic community expected in all reservoirs, except in El Atazar (see reference community in Section 8.1), should be characteristic of siliceous and mesotrophic waters (Margalef, 1976; group A in Sabater & Nolla, 1991), and should consist of diatom taxa such as Melosira (Aulacoseira) distans, Tabellaria flocculosa, Fragilaria crotonensis, with some chlorophyte taxa (Dictyosphaerium pulchellum), but desmidiaceae would be absent. The phytoplanktonic density should range from 100 and 10.000 cells/ml (mesotrophic reservoirs). Macrophytes. Hydromorphological conditions do not allow the establishment of a macrophyte community in the littoral zone. Benthic invertebrate fauna. The benthic reference community should consist of characteristic species from mesotrophic reservoirs with cold waters and low mineral content, except in El Atazar (see reference community in Section 8.1). The slight increase in phytoplanktonic production in mesotrophic reservoirs with regards to oligotrophic ones would favour the presence of phytophagous chironomids
57 (Stictochironomus and Chironomus), which would occur together with the reference taxa described in 8.1 in those reservoirs of intermediate depth (Pinilla). Among the oligochaetes cited in Section 8.1, other cosmopolitan and ubiquitous genera such as Limnodrilus spp. and Tubifex tubifex, would be present as well. Fish fauna. Fish community in mesotrophic reservoirs corresponds to that reference community described in Section 8.1 (Salmo trutta, Chondrostoma polypelis, Leuciscus pyrenaicus and Rutilus arcasii) but accompanied by high densities of Barbus bocagei. Hydromorphological quality elements To maintain the current reservoir use of the river Lozoya reservoirs, water level fluctuations would be inevitable, and consequently, the littoral zone would remain without riverine vegetation. Physico-chemical quality elements Nutrient content should correspond to mesotrophic conditions (except in El Atazar, where they should correspond to oligotrophic conditions). Mean annual chlorophyll content should be >2 mg/m3 and phosphorus content should range between 0.01 and 0.1 mg/L according to classification criteria of trophic status in Spanish reservoirs (Morguí, 1991) and ranges established by the OCDE.
9.2 Identification of Measures for Protecting and Enhancing the Ecological Quality
WFD Art. 11 requires the establishment of a programme of measures, taking into account the impact of the human activity and an economic analysis of water use (Art. 5), in order to achieve good ecological potential (Art. 4iii) of the heavily modified water bodies. To protect and enhance the ecological quality of the water bodies, each programme of measures shall include “basic measures”, which are the minimum requirements to be complied with, and “supplementary measures”, which are those measures designed and implemented in addition to the basic measures, with the aim of achieving the environmental objectives established pursuant to Art. 4.
9.2.1 Basic Measures
From all the basic measures cited in Art. 11.3 and Art.10, the following measures have been are proposed for the river Lozoya reservoirs: 1. Efficient and sustainable water use 2. Controls over the abstraction of fresh surface water (periodically reviewed and, where necessary, updated) 3. Safeguard water quality 4. Controls for point source discharges and diffuse sources (such as nutrient loadings that cause eutrophication in reservoirs). To reduce the trophic status in reservoirs from oligotrophic to mesotrophic conditions, the necessary measures considered here are those proposed by the CAM (“Additional wastewater treatment required in susceptible areas”/“Necesidades de Complementación de Depuración en Zonas Sensibles”):
58 • Creation of wetland areas at: − the riverine zone of Pinilla reservoir − La Nava stream (Puentes Viejas reservoir) • Construction of wastewater treatment plants associated with discharges into the following rivers and streams: − Pinilla stream (Riosequillo reservoir) − La Nava stream, river Madarquillos and river Trocha de Cigüeñuela (Puentes Viejas reservoir) − river Recombos (El Atazar reservoir) Apart from implementing these measures, the following directives should be observed (Annex VI part A): i) The Pollution Reduction Directive (76/464/CEE) ii) The Integrated Pollution Prevention Control Directive (96/61/CEE)* iii) The Nitrates directive (91/676/CEE) iv) The Urban Waste-water treatment Directive (91/271/CEE) v) The Drinking Water Directive (80/778/CEE) as amended by Directive 98/83/CEE* vi) The Environmental Impact Assessment Directive (85/337/CEE) vii) The Habitats Directive (92/43/CEE) viii) The Birds Directive (79/409/CEE).
*Non-transposed directives into Spanish legislation
Table 41 Directives and Spanish legislation
Directive Transposition into Spanish legislation Efficient and 85/337/CEE Real Decreto-Legislativo 1302/1986 de evaluación de impacto sustainable water ambiental use 79/409/CEE Ley estatal 4/1989 de conservación de los Espacios Naturales y de la Flora y Fauna Silvestres, y Real Decreto 439/1990 que regula el catálago nacional de especies protegidas (modificado por Órdenes Estatales 9/6/1999 y 10/3/2000, incluyéndose, cambiándose o excluyéndose especies) Safeguard water 91/271/CEE Real Decreto-Ley 11/1995 y Real Decreto 509/1996 por los que se quality establecen las normas aplicables al tratamiento de aguas residuales urbanas 80/778/CEE Real Decreto 1138/1990 por el que se aprueba la Reglamentación Técnico Sanitaria para el abastecimiento y control de calidad de las aguas potables de consumo público Controls for point 76/464/CEE Orden 12/11/1987 sobre vertidos de aguas residuales source discharges Controls for diffuse 91/676/CEE Real Decreto 261/1996 sobre protección de las aguas contra la sources contaminación producida por nitratos procedentes de fuentes agrarias
59
9.2.2 Supplementary Measures
The supplementary measures (Art. 11.4 and Annex VI part B) that would contribute to delivering environmental improvement are described below. The first two are current legislative instruments that should be modified by means of applying basic measures (described in Section 9.2.1). i) Central government legislative instruments (Ministry of the Environment): River Tajo Basin Management Plan (“Plan Hidrológico de la Confederación Hidrográfica del Tajo”), and this Plan should include: − Programme to determine environmental quality objectives − Programme to define and establish minimum flow − Programme to protect ecosystems ii) Autonomous government legislative instruments (Autonomous Community of Madrid, Consejería de Medio Ambiente): Resource Management for reservoirs, Forestry Plan from the CAM, Director Plan of wastewater treatment of all municipalities of the CAM. iii) Negotiated environmental agreements among Confederación Hidrográfica del Tajo, Canal Isabel II and Autonomous Community of Madrid: for the management of reservoir operations and water withdrawal (for example, multilevel selective withdrawal). iv) Promotion of adapted farming and agricultural production (codes of good practice) v) Research, development and demonstration projects: − Monitoring studies on ecological quality of reservoirs − Studies on the regeneration of the littoral zone of reservoirs − Studies on the de viability of creation of wetland areas − Studies on the viability of construction of pre-reservoirs vi) Efficiency and reuse measures, inter alia, promotion of a rational water use and urban water rate and water-saving techniques (Autonomous Community of Madrid together with Canal Isabel II).
9.3 Discussion and conclusions
Lessons learned Good ecological potential at medium and long term in the river Lozoya reservoirs would be achieved with the reduction of the trophic status. This would be achieved by complying with the above-cited directives (basic measures) and the implementation of strategies to reduce the nutrient loadings into reservoirs (construction of wastewater treatment plants, creation of wetland areas and pre-reservoirs, controls over agricultural and farming activities within the watershed, etc.).
60 Problems encountered and how they were overcome Water level fluctuations are an unsettled aspect as they prevent continuity with terrestrial ecosystems. Very detailed analyses of the annual water rate evolution (and future demands) at the Autonomous Community of Madrid are needed to establish a management reservoir model that diminishes the water level fluctuations. Construction of small reservoirs in the riverine zone of Pinilla reservoir, is a measure to be considered, as it would allow certain flow regulation and an adequate habitat for aquatic flora and fauna. Dams, besides, represent a disruption in the continuity of the river, and therefore, have negative consequences on the fish fauna, and to a lesser extent, on the macroinvertebrates. Elevators are especially required to connect reservoirs and fluvial stretches.
61 PART III
62 10 Conclusions, Options and Recommendations
10.1 Conclusions
Lessons learned concerning the treatment of heavily modified water bodies in the Water Framework Directive. Applicability of results in other river basins in the same ecoregion (of your country).
10.2 Options and Recommendations
[Recommendations should be of general nature and pertain to the objectives of the European project on heavily modified water bodies. In particular, items for consideration in the harmonised and consistent implementation of the Water Framework Directive should be discussed. Highlight any clarifications of Annexes or guidelines that may be needed or helpful.]
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65 García de Jalón, D. (1979). Estudio de las comunidades de macroinvertebrados, especialmente del orden Trichoptera, del río Lozoya. Tesis doctoral. Escuela Técnica Superior de Ingenieros de Montes. Univ. Politécnica de Madrid. García de Jalón, D. (1980). Efectos del embalse de Pinilla (Madrid) sobre las comunidades de macroinvertebrados bénticos del río Lozoya. Boletín de la Estación Central de Ecología, pp. 47-52. García de Jalón, D. (1981). Los Trichoptera del río Lozoya. Boletín de la Asociación Española de Entomología, vol. 5, pp. 41-58. Hidráulica Santillana. Centrales hidroeléctricas. Junta de Castilla y León (1989). Estudio diagnóstico de la calidad de las aguas embalsadas de Comunidad de Castilla y León: determinación y previsión de impactos, propuesta de corrección y red de vigilancia. Margalef, R., Planas, D, Armengol, J., Vidal, A., Prat, N., Guiset, A.., Toja, J & Estrada, M. (1976). Limnología de los embalses españoles. Dirección General de Obras Hidráulicas, Ministerio de Obras Públicas, Madrid, 422 pp. Morguí, J.A. (1991). Eutrofización: situación del problema en España. Ingeniería Química, agosto 1991. Martín, A. (1997). Marco conceptual y desarrollo metodológico para la caracterización y modelado de caudales de compensación de los ríos mediterráneos continentales (río Lozoya, cuenca río Tajo, España). Tesis doctoral. Facultad de Ciencias Biológicas. Universidad Autónoma de Madrid. Munné, A., Solà, C., Rieradevall, M. & Prat, N. (1998). Index QBR. Mètode per a l’avaluació de la qualitat dels ecosistemes de ribera. Estudis de la qualitat ecològica dels rius. Diputació de Barcelona, Àrea de Medi Ambient. Munné, A. & Prat, N. (2000). Establishing ecological regions to predict the ecological status of rivers. EurAqua Meeting, Madrid, Octubre 2000. MOPU. Inventario de las zonas húmedas. INITEC. Ortiz de Zárate, M.V.; Herraiz Ferreiro, J.A; et al. (1980). Estudio de la vegetación del Alto valle del Lozoya. Revista mensual de gestión ambiental. Año 2 – nº. 23. Editorial: La Ley. Prat, N. & Munné, A. (2000). Problemas y perspectivas en la definición del estado ecológico de los ecosistemas fluviales peninsulares. Comunicación Congreso Oporto 2000. Prat, N. & Munné, A., Rieradevall, M. & Bonada, N. (2000). La determinación del estado ecológico de los ecosistemas acuáticos en España. En: “La aplicación de la Directiva Marco del Agua en España”: Real, M. (1993). Ecologia del bentos profund als embassaments de l’estat espanyol. Tesis doctoral. Facultat de Biologia. Universitat de Barcelona. Riera, J. L. (1993). Regional limnology of spanish reservoirs. Relationships between nutrients, seston and phytoplankton. Tesis doctoral. Facultat de Biologia. Universitat de Barcelona. Riera, J.L., Jaume, D., de Manuel, J., Morgui, J.A. & Armengol, J. (1990). Patterns of variation in the limnology of Spanish reservoirs: a regional study. Limnetica, 8: 111-123. Vega, J.C., Rodríguez de Lema, G., Rieradevall, M. & Prat, N. (1993). Research and environmental management in the Sanabria Lake Natural Park (NW Spain), Proc. 5th Int. Conference on the Conservation and Management of Lakes, pp. 491-494.
66 12 List of Annexes
Annex 1: Maps Annex 2: Tables Annex 3: Figures
67 Annex 1: Maps
68 Annex 2: Tables
69 Annex 3: Figures
70