Groundwater use in Spain: an overview in light of the EU Water Framework Directive

Abstract

In semi-arid regions, aquifers provide a series of practical advantages that make them preferential sources of water supply. In Spain, groundwater meets about one-fifth of the total water demand and is used to irrigate over one-third of the total irrigated land. This article examines groundwater use in Spain from the perspective of the EU Water Framework Directive. Analysis of different sector uses suggests that core problems (and solutions) related to groundwater lie in agricultural uses and that the Directive's environmental requirements remain distant from reality on the ground, where economic, political and social reasons prevail on legal obligations set by national and supranational authorities.

Keywords::

• groundwater management
• Water Framework Directive
• irrigation
• domestic supply
• pollution
• unauthorized use
• Spain

Introduction

The importance of groundwater in many regions of the world is widely acknowledged in the literature. In the European Union (EU) groundwater is a strategic resource, especially for urban supply, where it meets about 55% of the domestic demand (EEA, 2010). In Southern Europe the role of aquifers is even more relevant, as groundwater represents more than 33% of the blue water used for irrigation (EASAC, 2010) and is a strategic resource during droughts. At the same time, scholars and water practitioners acknowledge the challenge of controlling groundwater (De Stefano & López-Gunn, 2012; Minciardi, Robba, & Sacile, 2007; Shah, 2009) and the implications of its intensive use on water-table levels and groundwater quality (Custodio, 2002; Menció & Mas-Pla, 2010; Shi et al., 2011). Spain, with a semi-arid climate in most of its territory, is no exception to these features, and is an interesting laboratory in which to analyze groundwater development dynamics and the different policy attempts to manage intensive groundwater use.

Spain, as an EU member state, has to shape its water policy in accordance with EU regulations. The Water Framework Directive (WFD, approved in 2000; EU, 2000) constitutes an environmentally oriented legal umbrella requiring EU countries to achieve good status in all their waters – including groundwater – by 2015, or 2027 at the very latest. This objective suggests that the Directive strives to re-establish balance between the three tiers of sustainable development by acknowledging the economic and social dimensions of water management and emphasizing the environmental one, which has often been neglected, as shown by the poor quality of many aquatic ecosystems. Thus, the benchmark for the success of WFD implementation is the environmental quality of EU water resources by 2027.

The article looks at groundwater use in Spain through the lenses of the WFD and explores how the achievement of its objectives unfolds in the case of groundwater. After presenting an overview of groundwater uses and status in Spain, the article explores the implications of urban and industrial groundwater uses and points to the central role of agriculture in determining the status of groundwater bodies. The last section concludes, summarizing the main take-home messages about the difficult balance between socio-economic development and good groundwater status.

Overview of groundwater resources in Spain

Groundwater uses

The WFD requires EU countries to elaborate river basin management plans (RBMPs) by 2009 – and then revise them every 6 years – based on baseline information about water resources status. The WFD baseline studies identified 777 groundwater bodies (GWBs), stretching across about 360,000 km², or 70% of Spain's territory, and storing over 300,000 hm³ (López-Geta & Fernández Ruiz, 2013) – see Figure 1. The groundwater share of the average annual runoff (111,000 hm³) is estimated at 29,900 hm³ (MIMAM, 2000). This accounts for almost 9% of the annual precipitation and is the main component of in-stream flows during dry periods.

Figure 1 Groundwater bodies in Spain, showing the location of case studies discussed in the text: (1) Sierra de Crevillente; (2) Western La Mancha; (3) Poniente Almeriense; (4) Loma de Úbeda; (5) Western Doñana. Adapted from De Stefano et al. (2013).

Groundwater resources available for abstraction after discounting environmental needs are estimated at about 25,000 hm³/y (De Stefano, Martínez-Santos, Villarroya, Chico, & Martínez-Cortina, 2013). This represents a significant share of the regulated water resources, as the storage capacity of reservoirs for consumptive use is about 55,400 hm³ and the average surface-water reserve for consumptive use during the past 10 years was approximately 33,400 hm³ (MAGRAMA, 2012).

Largely as a consequence of the lack of direct water metering and of the fact that water rights registers often do not fully reflect real uses, most planning documents can only estimate actual groundwater abstraction. Undoubtedly, a pending issue for the Spanish water authorities is to put their official water registers in order to revise water rights that are no longer in use – but that are accounted for in estimates – and to clarify the legal situation of many wells that are used ‘informally’ and thus are rarely accounted for in official estimates (López-Gunn, Rica, & Van Cauwenbergh, 2013).

Estimated overall groundwater abstraction is now about 7000 hm³/y, which corresponds to about 22% of Spain's total water demand (31,500 hm³/y) (De Stefano et al., 2013). It should be noticed that RBMPs mainly provide estimates of groundwater demand – which represent estimates of potential abstraction, not necessarily actual abstraction – from registered water rights, adjusted using direct abstraction measurements, as well as mixed (e.g. remote sensing) and indirect methods (e.g. statistical data on population or crop areas, multiplied by an average water rate). This combination of methods and some possible misconceptions around groundwater often lead to a certain level of disparity in the data provided by different sources (López-Vera, 2012). In the case of surface water or global values this article will use the term ‘demand’, as official figures are mostly only estimates of water demand for different uses. It should be noticed, however, that those estimates make no reference to the price to be paid for the demanded good, as one would expect when quantifying a demand.

Aquifers supply water to about 13 million inhabitants (28% of Spain's population) (López-Geta, Fornés, Ramos, & Villarroya, 2009) and are used to irrigate over one-third of irrigated land (0.9 million of 3.3 million hectares). They also provide for almost one-fourth of the industrial demand (about 360 hm³/y of 1400 hm³/y, see Table 1 ) and are key for hydrological functioning of rivers and wetlands.

Table 1 Estimated groundwater abstraction (mainly based on estimates of groundwater demand) and overall water demand (surface and groundwater). Based on De Stefano et al. (2013) and López-Geta and Fernández Ruiz (2013).

	Estimated groundwater abstraction (hm^3/y)	Total water demand (hm^3/y)
Domestic supply	1,400–1,500	5,200
Agriculture	4,300–5,000	25,000
Industry	360	1,400
Recreational uses	65	130
Total	6,125–6,925	31,730

Comparison of the estimated groundwater abstraction with the estimated available resources suggests that there is margin for increasing groundwater use. Still, this should be done using a planned approach and applying the precautionary principle, to avoid altering natural dynamics through localized intensive abstraction or jeopardizing the reliability of supply during dry spells. In Madrid, for instance, the domestic water supply company abstracts groundwater mostly only during droughts, through approximately 90 wells with a total pumping capacity of 100 hm³/y (Villarroya, 2010).

Groundwater status

The WFD requires all GWBs to have good status by 2015, although it is possible to establish time extensions to 2021 and 2027 or to set less stringent objectives for those GWBs where good status cannot be met without incurring disproportionate costs. Both options introduce a flexibility that, while needed to adapt the WFD to very specific socio-economic and technical circumstances, potentially can undermine the effectiveness of the Directive in achieving a real improvement in groundwater status. At the end of 2013, approximately 40% of the GWBs had poor status (Figure 2). About 25% had poor quantitative status, and 30% did not meet the quality standards set in Annex V of the WFD, which are monitored through water conductivity (to detect salt intrusion) and the concentration of a number of pollutants defined in the EU legislation. In a sample of 107 GWBs with poor chemical status, 32% had salinization problems; 26% had high nitrate content; 22% were affected by point and diffuse pollution; and 20% by high concentrations of arsenic or per- or trichloroethylene (personal communication, Pérez Baviera, General Directorate for Water, MAGRAMA).

Figure 2 Current status of groundwater bodies. Adapted from De Stefano, Martínez-Santos, Villarroya, Chico and Martínez-Cortina (2013).

Following the WFD requirements, the new RBMPs state that at the end of the last planning cycle (2027) about 80% of the Spanish GWBs will meet the objective of good status, while less stringent objectives have been set in 4% of the GWBs (De Stefano et al., 2013). In the remaining GWBs available data are insufficient to predict their status by 2027. Pollution, mainly by nitrates, is the main cause of non-compliance with good status objectives and for establishment of less stringent objectives (De Stefano et al., 2013).

Eventually, the magnitude of the challenge will be determined by the origin and severity of the pollution, by how entrenched the problem of overdraft is, and by how water quality and quantity dynamics interact. This requires, on one hand, considering the legal and institutional context where groundwater uses occur and, on the other hand, understanding the drivers contributing to poor groundwater status.

Institutional framework

The 1985 reform of Spain's Water Act put groundwater under public ownership. This means that water abstracted from wells drilled from 1986 onwards is public. However, users abstracting groundwater before 1986 could opt to keep their water rights private. As a result, the overwhelming majority of groundwater rights are still private, creating situations of high legal complexity because public and private ownership entails different rights and obligations for users and different legal options and constraints for water authorities. Furthermore, unlicensed groundwater use is a reality that water authorities rarely acknowledge officially. Unofficial estimates put the number of unauthorized wells at over half a million; 90% of existing wells may be illegal or in legal ‘limbo’ (De Stefano & López-Gunn, 2012).

Water resources are managed at the river basin district (RBD) level, either by river basin organizations (depending on the central government) or by regional water agencies (depending on a regional government). These water authorities are in charge of elaborating the RBMP and ensuring the compliance of the WFD objectives in their RBD.

As it is widely acknowledge in the literature (e.g Blomquist, 1992; Ostrom, Stern, & Dietz, 2003; Stern, Dietz, & Ostrom, 2002), water users play a key role in groundwater management, and their decisions largely determine the success or failure of any groundwater-related public policy. In Spain there is a rather long tradition of water user associations. The first association of groundwater users dates back to 1976, when groundwater users – mainly industrial ones – in the Llobregat Delta (Catalonia, north-east Spain) decided to associate to interact with and lobby the water authorities. Since then many groundwater users across Spain have formed associations, which vary in legal status, size, composition and territorial scope (López-Gunn, Cabrera, Custodio, Huertas, & Villarroya, 2013; Rica, López-Gunn, & Llamas, 2012). These associations facilitate a coordinated use of the water resources that users share (reservoirs, community wells, etc.) and defend the interests of their members before the authorities or other entities (e.g. energy providers, brokers).

Groundwater use for domestic supply

In 2011, Spain's public domestic supply networks distributed 4514 hm³ of water, out of which 1354 hm³ (30%) was abstracted from aquifers (INE, 2013). Average domestic water supply was 142 litres per person per day, and the average price paid was €1.54/m³ (INE, 2013). Groundwater share varies between 19% in settlements with more than 20,000 inhabitants and 70% in those with less than 20,000 inhabitants. Groundwater is key for domestic supply in the Canary Islands (56% of the total domestic demand), the Balearic Islands (82%), Jucar (59%), Andalusian Mediterranean RBDs (42%) and several RBDs in northern Spain (De Stefano et al., 2013).

Domestic supply is managed by municipalities directly, through an association of municipalities (mancomunidad) or through utility companies (public, private or mixed). Municipalities act within the legal framework defined by their regional governments, which also supervise pricing policies (Maestu & Del Villar, 2007). Small municipalities in some cases have significant difficulties in managing the supply in a professional manner. This can affect the economic and technical efficiency of the service and is the reason why small municipalities often opt to operate through mancomunidades or similar super-municipal bodies.

In many urban areas, groundwater is a strategic resource to prevent failures in the urban supply system, especially during droughts. For instance, during a dry spell at the end of the 1980s, the cities of Bilbao, Vitoria and San Sebastian (in northern Spain) had water shortages due to their strong dependence on surface water, while nearby cities such as Santander and Pamplona did not, largely due to their conjunctive use of surface and groundwater (González Lastra & Sanz de Galdeano, 1991). Conjunctive use is also important in Barcelona (López-Geta, 2013) and in Madrid, which is perhaps the best-documented Spanish example of conjunctive use during droughts. The supply system for Spain's capital serves about 6.5 million inhabitants and is designed to ensure meeting 100% of the demand in 96 of every 100 years (Sánchez, Muñoz, Iglesias, & Cabrera, 2003). The system includes 14 surface reservoirs with a total storage capacity of 946 hm³. Additionally, it can abstract water directly from two rivers and use groundwater strategically: wells in the detrital aquifer of Madrid are used intermittently to allow recuperation of the water table (Figure 3).

Figure 3 Water table trends of the wells of Madrid's supply company. Abstraction periods are followed by inactivity periods that often last twice as long as the pumping ones, to ensure the full recovery of the water table levels. From Sánchez et al. (2003).

Locally, domestic demand can cause important pressure on aquifers, from a quantitative and a qualitative perspective. This is especially significant in coastal areas, where about one-third of Spain's population lives and where an important share of the national economy develops. For instance, in the Valencia region, on the Mediterranean Coast, 80% of the population and 90% of the regional GDP are less than 100 m above sea level (Fornés, De la Hera, Ballesteros, & Aragón, 2008). Urban agglomeration, peak demands for tourism, and irrigation all contribute to groundwater over-abstraction and cause seawater intrusion. Surprisingly, there are no recent data on the magnitude of seawater intrusion in Spain's coastal areas. Data from 1994 (MOPTMA-MINER, 1994) show of 58% of the coastal hydrogeological units in Spain being affected by seawater intrusion as a direct result of over-exploitation of freshwater resources.

Other sources of concern for groundwater quality are related to uncontrolled urban discharges and the absence of sufficient regulation of emerging organic contaminants (EOCs). These are natural or synthetic products such as active pharmaceutical compounds, drugs or oestrogens that usually are not monitored despite their potential negative impacts on human health and the environment. EOCs are likely to enter to the aquifer mainly through the effluents of wastewater treatment plants and are present in groundwater at concentrations of ng/L to μg/L. It is important to mention, however, that compared to rivers, aquifers are considerably less contaminated by these compounds, which may be indicative of their natural attenuation capacity (Jurado et al., 2012).

Natural bank filtration from rivers that receive large amounts of effluents from wastewater treatment plants has turned out to be the most influential source of contamination. For instance, 72 pharmaceuticals along with 23 of their transformation products were detected in groundwater underlying the city of Barcelona – antibiotics and analgesics were the most frequently found compounds – at levels reaching 100 ng/L (López-Serna et al., 2013). Interestingly, in that case groundwater showed a broad range of compounds in concentrations as high as the river itself, or even higher. López-Serna et al. attribute this to the progressive accumulation of pollutants in the aquifer and to the fact that abundant spring rains had increased pollution dilution in the river. The connection between surface and groundwater pollution highlights the need to keep improving wastewater treatment capacity in many Spanish urban areas.

Reclaimed water is another source of pollution. In Gran Canaria Island, irrigation with reclaimed water has been practised for over 30 years and currently represents 8% of water resources. Reclaimed water and groundwater were monitored quarterly from July 2009 to May 2010. EOC concentrations registered were always below 50 ng/L, although some pharmaceuticals and one pesticide (chloropyrifos ethyl) were occasionally detected at higher concentrations (Estévez, Cabrera, Molina-Díaz, Robles-Molina, & Palacios-Díaz, 2012). Similarly, in the Llobregat Delta (south of Barcelona), where reclaimed water is employed for in-stream flows, irrigation and the construction of a hydraulic barrier against seawater intrusion, groundwater monitoring revealed widespread pharmaceuticals and chemicals (Teijon, Candela, Tamoh, Molina-Díaz, & Fernández-Alba, 2010).

Arsenic pollution is linked to mining activity and to mobilization of arsenic naturally present in the aquifer matrix, e.g. in the detrital aquifer of Madrid and in the Douro Basin. In the latter case, concentrations of arsenic over 10 μg/L (recommended concentration) were detected in domestic supply wells, leading to sealing of domestic supply wells in over 500 municipalities (Cama et al., 2008). Thus, in areas prone to arsenic mobilization, having a good monitoring system is key to controlling arsenic movement in the aquifer.

Pollution by nitrates or arsenic, as well as induced salinization, are often addressed by reducing dependence on groundwater and searching for other sources such as reservoirs, water transfers, and more recently desalination plants. (For more on desalination in Spain, see García-Rubio & Guardiola, 2012.) Examples can be found in the towns of Valladolid, Segovia and Ávila (Douro Basin, central Spain); in Castellón, Alicante, Almería and Barcelona (Mediterranean coast); and in Seville and Cádiz (Andalusia, southern Spain). This type of solution has important economic and environmental implications, and contributes to neglecting the recovery of groundwater quality. However, it is often seen as a solution that is easier than tackling the causes of pollution, which would require acting against well-established water uses and economic interests associated with irrigated agriculture and intense urbanization.

Groundwater use for industry

According to the Spanish National Institute of Statistics (INE, 2009), overall water supply for manufacturing industries is 1393 hm³/y (including water for ‘cooling’), of which 960 hm³/y is self-supplied. Of this, 340 hm³/y is abstracted from aquifers. In the case of extractive industries, 68 hm³/y (93% of their water supply) is self-supplied, 21 hm³/y from aquifers.

During the past few years, spurred by public support for green energy production, new solar thermal power plants have added to existing industrial water demand, especially in the Guadiana and Guadalquivir River basins (central and southern Spain), accounting for 20 hm³/y. This new groundwater demand is often met by shifting water resources from other uses, mainly agriculture. Finally, the mineral-water bottling industry demands about 5 hm³/y.

In general, challenges and problems derived from the industrial sector are similar to those from urban water supply. Perhaps the most frequent and severe impact of industry on groundwater status is due to uncontrolled industrial waste disposal, as well as uncontrolled or accidental spills of industrial by-products. For instance, López-Geta et al. (2009) estimate that industry generates more than 3 million tons of toxic and hazardous wastes per year, of which only 20% is treated. Additionally, there are more than 30,000 fuel tanks in gas stations and more than 300,000 hydrocarbon tanks for domestic use, which are all potential sources of aquifer pollution. Table 2 summarizes some cases of pollution associated with industrial activities.

Table 2 Selected cases of groundwater pollution due to industrial activity in Spain

Location and year	Causes	Pollutants and remediation
Lower Llobregat, Barcelona, 1974 (1)	Dumping of industrial and urban waste in an abandoned arid extraction site	Chlorinated solvents, mainly perchloroethylene; hydraulic barriers and abandonment of the polluted wells
Albolote village, Andalusia, 1988 (2)	Pollution of domestic supply wells due to a spill from an underground pipeline of a factory located 300 m from the urban area	50,000 litres of hydrocarbons
Detrital aquifer of Madrid, 1992 and 1993 (3)	Leakage from two gas stations in two towns close to Madrid	Hydrocarbons (200,000 litres from one of the gas stations)
Llobregat Delta, Catalonia, 1994 (1)	Pollution of domestic supply wells, attributed to illegal industrial discharge into an abandoned well	High concentration of trichloroethylene; actions to guarantee supply and water purification cost over €1.6 million
La Llagosta aquifer, Catalonia (4)	Infiltration of waste water from septic tanks and sewage networks, and by industrial activities located in urban areas	High contents of NO3 (90–100 mg/L) and an increase in the concentrations of Ca and Mg
Troya karstic aquifer, Guipúzcoa, (N Spain) 1995–1997 (1)	Abandonment of a sulphur mine in 1993; pollution caused fish mortality in the stream draining the mine	The polluted water had a high content of SO4 (1.5 mg/L) and dissolved minerals (50 mg/L of Fe and 5 mg/L of Zn)
Llobregat basin, Balsareny, Sallent and Suria villages (Bages region, Catalonia), 1960–present (5)	Dumping of salt waste (70 million tonnes) from mining – to extract KCl – into non-sealed and non-covered fields (100 ha), and subsequent leaching of pollutants	High content of chlorides (>14% in some aquifers); waste covering and salt removal through collectors to the sea
Guadiamar Basin, Aznalcóllar mines (Doñana National Park, Andalusia), 1998 (6)	Leakage of 3.6 million m^3 of contaminated water and 1 million m^3 of toxic mud, affecting 5500 ha, including the Agrio River, due to the collapse of a mining tailing pond	Pyrite (86% content in wastes) and other sulphur compounds, and metals like lead, zinc, arsenic and copper

Source: (1) Arenas Cuevas & Godé Lanau (1999), (2) Cruz-Sanjulián, Olías, Valle-Cardenete, & Rubio (1992); (3) J.M., Fornés, pers. comm.; (4) Navarro & Carbonell (2007), (5) La Calle (2013) and (6) Simón et al. (1998)

In this field, a first challenge is ensuring the enforcement of existing legislation, which is sometimes lax due to the local economic importance of the polluting activity. For example, in the Bages region (north-east Spain), a large potash mining company continues to operate despite the serious impact of its salt waste disposal on local water resources (La Calle, 2013). A second challenge is ensuring the economic and legal liability of polluters, which in some cases is avoided through lengthy legal processes, as occurred with Boliden-Apirsa, the mining company responsible for the 1998 pollution accident in Doñana, Andalusia (Table 2).

Groundwater use for irrigation

As in many countries worldwide, agriculture is the main groundwater user in Spain (73% of the total estimated groundwater abstraction). The economic value of groundwater agricultural production is about €4700 million per year, or 30% of the value of irrigated production (average for 2005–2008; De Stefano, Martínez-Cortina, & Chico, 2013).

In terms of groundwater quality, overdraft for irrigation is an important cause of induced aquifer salinization. Additionally, agriculture is responsible for diffuse pollution by fertilizers and pesticides, which is a widespread problem globally (EEA, 2003; Watson, 2001) and is the major and growing source of groundwater pollution across many OECD countries (Parris, 2011). This is largely because other sources of pollution have been reduced more rapidly than agricultural ones, although evidence of groundwater pollution is limited. This is a particular concern for countries where groundwater provides a major share of drinking-water supplies for both human and livestock populations; also, natural recovery from pollution can take many decades, especially in deep aquifers. There is also some evidence of increasing pollution of groundwater from pesticides, despite lower use in many cases, largely explained by the long time pesticides can take to leach through soils into aquifers. In Spain, 173 groundwater bodies have been declared to be in poor status due to this type of pollution. So far, the main instrument to address this problem has been EU Directive 91/676/CEE (Council of the European Union, 1991) concerning the protection of waters against pollution caused by nitrates from agricultural sources, which in Spain has led to the identification of 8 million ha as ‘vulnerable’ to nitrate pollution (MAGRAMA, 2012).

The Directive requires the definition of codes of good agricultural practice for farmers, establishment of action programmes, and periodic reporting to the European Commission. According to the official report (EC, 2013), in Spain during the 2008–2011 period pressure from agriculture decreased (relative to 2004–2007), and the nitrate monitoring network was expanded, adding about 700 new groundwater monitoring points. However, there is still an imperative need to prevent and reduce nitrate pollution: over 40% of the groundwater monitoring points registered concentrations higher than 25 mg/L, and about half of those exceeded the 50 mg/L limit (EC, 2013).

In many regions, groundwater-irrigation expansion has resulted in significant socio-economic development. In Andalusia, some areas have a thriving local economy based on exports of groundwater-irrigated berries and fresh vegetables, with apparent water productivity of €8.5/m³ (Aldaya, García-Novo, & Llamas, 2010) and €7/m³ (Dumont, López-Gunn, & Llamas, 2011), respectively. In other areas the shift of traditionally rainfed crops such as vines and olive trees to groundwater irrigation has radically transformed formerly deprived areas. Often, however, the spectacular growth of groundwater irrigation has occurred in an uncontrolled way, and is largely responsible for the poor status of Spain's groundwater bodies and environmental degradation of the associated aquatic ecosystems. For example, in the Guadalquivir Basin between 2002 and 2008, the area of olive-tree plots irrigated with groundwater increased by 53%, mostly without the authorization of the Guadalquivir River Basin Authority (Corominas, 2011).

Analysis of several case studies in the southern part of Spain (Sierra de Crevillente, Western La Mancha, Poniente Almeriense, Loma de Úbeda, and Western Doñana, see Figure 1) allows the identification of common patterns in groundwater development for irrigation (Table 3; a full description of these case studies is given by De Stefano, López-Gunn, & Martínez-Santos, 2014).

Table 3 Comparison of key characteristics of five selected case studies of intensive groundwater use for irrigation. Y: yes; N: no.

	Sierra de Crevillente	Western La Mancha	Poniente Almeriense	Loma de Úbeda	Western Doñana
Dominant crops	Table grapes	Wine grapes	Fresh vegetables	Olives	Berries
Water quality degradation	Y	Y	Y	Y	Y
Efficient water use	Y	Y	Y	Y	Y
Conjunctive use	Y	N	Y	Requested	Requested
External resources	Y	Y	Requested	N	Requested
Unconventional resources	?	?	Y	N	N
Users' collective action	Y	Y	Y	Y	Y
Legal pitfalls	?	Y	Y	Y	Y
Recovery of the costs of intensive use	N	N	N	N	N
Land-use policy supporting irrigation	Y	Y	Y	Y	Y

During the past four decades, management strategies to deal with intensive groundwater use have evolved significantly, following four main ‘waves’ (Figure 4). At the beginning of the groundwater ‘boom’, the number of wells grew in a paced manner (first wave: ‘silent revolution’) while water authorities focused their attention and efforts mainly on surface-water development. Soon, however, different, concomitant drivers – e.g. the approval of the 1985 Water Act (Boletín Oficial del Estado, BOE, 1985), EU subsidies to irrigated crops and a severe drought – led to a frenzy of drilling activity, which in turn caused a sharp increase in groundwater abstraction and the subsequent drop in water-table levels.

Figure 4 Evolution of strategies to manage intensive groundwater use in agriculture. Adapted from De Stefano et al. (2014).

Water authorities reacted using the legal instruments established in the 1985 Water Act (second wave, ‘command-and-control’), but their effectiveness was hindered by limited resources and the lack of political backup to curb unauthorized groundwater use. In some cases, water authorities employed EU-funded economic instruments to temporarily reduce irrigation but failed to change crop patterns in a lasting way (Martínez-Santos, De Stefano, Llamas, & Martínez-Alfaro, 2008). At the same time, the consolidation and expansion of irrigation were strongly supported by the authorities responsible for land-use policies (i.e. regional authorities and the central Ministry for Agriculture). From the beginning of groundwater development in the 1970s until today, these public land-use policies have maintained their firm support of irrigation, first through direct subsidies to thirsty crops and then by subsidizing infrastructure to consolidate existing irrigation.

Groundwater users soon became aware of the threats posed by the water authorities' command-and-control approach and by the degradation of the groundwater resource due to overdraft. This led to the emergence of collective action around many aquifers (third wave, ‘users' self-organization’). Users began to associate, to protect their economic activities from sanctions and well closure; to pursue their legal recognition as water users before the water authorities; to lobby for new water resources to complement the shrinking or increasingly expensive groundwater resources (due to pumping costs); to seek public economic support to increase water-use efficiency; and to build critical mass to optimize access to water (e.g. through common wells and creating irrigators' advisory services or peer control of agreed abstraction rates). This phase allowed the progressive regularization of some of the unlicensed wells. This entails the legitimization of an activity that provides important incomes for some rural areas, but also means granting new 75-year-long water rights in aquifers that are already under severe pressure.

In the following phase (fourth wave, ‘technological fix’), water authorities and irrigation farmers have converged toward a common strategy aimed at ensuring the viability of the existing irrigated hectares, mainly through technological solutions. These include state-subsidized programmes for the modernization of irrigation systems and the search for additional water to complement groundwater resources and ensure the access to cheap (for users), good-quality water. Depending on the area, this can be surface-water transfer from other basins, desalinated water, reclaimed water, water traded through water markets or finely tuned conjunctive use. In this way, the water authorities implicitly acknowledge their inability to ‘undo’ the existing groundwater-based development and the water users realize the need to expand their pool of water sources.

At the national level, this approach led to the establishment of several large-scale public investment programmes: the 2001 National Hydrological Plan (BOE, 2001), whose cornerstone was a 650 km water scheme to transfer 1100 hm³/y from the Ebro River (in the north-east of Spain) to several areas along the Mediterranean Coast; the €8 billion AGUA Programme (BOE, 2004), which foresaw the construction of over 34 desalination plants along the Mediterranean Coast; and the €7 billion 2006 National Irrigation Modernization Plan (BOE, 2006) for the modernization of over 11 million hectares of irrigated land. These solutions, however, have some pitfalls. First, water efficiency improvements have come at the expense of a sharp increase in energy costs for irrigation and often have not resulted in a net decrease in water consumption (Lecina, Isidoro, Playán, & Aragüés, 2009). Second, substituting or complementing groundwater abstraction with surface-water resources in practice means ‘exporting’ water-scarcity problems to other water bodies. Third, public infrastructure such as desalination plants increases the water security of groundwater irrigators at the expense of the taxpayer, as public investments are not recovered through tariffs because farmers will use desalinated water only when it is their cheapest option.

During the last wave, aquifers supplying intensively irrigated areas have experienced a decrease in the pace of groundwater development and, in some cases, even a partial recovery of water-table levels. Possible reasons for this stabilization are a combination of different factors: during the past few years most of Spain has experienced an exceptionally wet period, allowing spectacular groundwater recharge, especially in calcareous aquifers; farmers have hit the ceiling in their capacity to sell their products to markets in a competitive way and, in some cases, perceive a threat from competing non-European regions with lower production costs; and, being aware that they have already reached (and exceeded) the physical boundaries of the available resources, water users have started focusing on consolidating their activity instead of further increasing the pressure on the resource.

Final remarks

The landscape of water use in Spain shows a dynamic and complex reality, where the boundaries across water sources and across water uses are becoming increasingly open and fluid. Water users increasingly apply an integrated approach to water use and combine available water resources based on accessibility, cost, quality, and timing of availability. Problems in one economic sector spill over to others; solutions have to be holistic.

Impacts of urban and industrial uses on groundwater status in absolute terms are small, given the magnitude of demand and the limited extent of the areas affected by their pollution. Preventive measures, vulnerability mapping and good monitoring systems are perhaps the most effective tools to tackle the impacts of those uses on groundwater bodies. Major groundwater problems originate in irrigated agriculture, both in quantitative (overdraft) and qualitative (nitrates and salinization) terms.

The spectacular and often uncontrolled growth of groundwater use for irrigation showcases the shortcomings of a command-and-control approach based on the enforcement of the 1985 Water Act (and its subsequent amendments) and suggests that for many groundwater bodies meeting the WFD requirements will be difficult. In areas with intensive groundwater use, the ‘one million-dollar question’ is how to reduce abstraction and improve water quality while maintaining the groundwater-dependent socio-economic system. As a matter of fact, solutions envisaged so far by water authorities and users contribute to improve water supply guarantees for irrigation but do not reverse groundwater degradation trends. As explained earlier, the RBMPs state that the percentage of GWBs in good status will increase from the current 40% to 80% in 2027. However, the reality observed on the ground and the present economic crisis in Spain cast doubts on the credibility of these objectives. In this context, the use of time extensions to postpone the achievement of good status to 2021 or 2027 risks becoming a way of postponing difficult decisions and leaving the substance of groundwater use unchanged. At the same time, the less stringent objectives, which in this planning cycle have barely been used (4% of the GWBs), still remain an option to be used in later stages, if no or little action is taken to change the status quo in groundwater use.

In Spain, groundwater management has little appeal for politicians and policy-makers for at least two reasons. First, its development does not requires large public investments (relative to e.g. surface water or desalination plants); thus, it brings little profit in terms of votes or popularity. Second, its nature as a common pool resource makes groundwater vulnerable to free-riding and can therefore require unpopular initiatives to ensure its sustainable management. Thus, it is no surprise that the official register of groundwater rights is still not complete or public, 28 years after its creation by the 1985 Water Act. This delay cannot be explained by technical problems; the cause is rather a lack of political will to put groundwater abstractions in order, and perhaps also an excess of legal complexity (often water users and the public administration engage in endless legal litigation over disputed water rights).

Since groundwater became a strategic resource for socio-economic development in many areas in Spain, a wide array of measures have been applied in an attempt to gain control over it. However, three key issues have constantly eluded resolution: (1) the recovery by groundwater users of the cost of measures to increase water availability in intensively used aquifers; (2) the poor transparency and accountability in relation to groundwater rights and to the actual cost of groundwater overdraft for the taxpayer; and (3) the fact that many of the decisions that affect water use are made outside the water planning sphere. Water authorities have little control of the catalysts of intensive groundwater use, and those administrations responsible for land-use planning do not necessarily see water protection as a priority. As long as there is no progress on these three aspects it is unlikely that the objective of good status of groundwater will be achieved.

Acknowledgements

The authors thank three anonymous reviewers for their comments and Mario Ballesteros for his help in the literature search and the preparation of graphic material for this article.