Networks of action situations in point-source pollution: the case of winery wastewater in Aragon, Spain

Vol.:(0123456789) 1 3 Sustainability Science (2023) 18:201–218 https://doi.org/10.1007/s11625-022-01273-1 SPECIAL FEATURE: ORIGINAL ARTICLE Networks ofaction situations inpoint‑source pollution: thecase ofwinery wastewater inAragon, Spain IgnacioCazcarro1,2 · SergioVillamayor‑Tomas3· MariaPilarLobera4,5· JoaquínMurría6· MaríaBernechea1,4,5 Received: 31 August 2021 / Accepted: 30 November 2022 / Published online: 16 January 2023 © The Author(s) 2023 Abstract In this article, we offer an analysis of point-source water pollution governance in the European agri-food sector. Specifically, we tackle the case study of the wine industry in Aragon (Spain) through the lenses of the networks of action situations approach. We unveil key strategic decisions of wine producers in relation to compliance with water discharge regulations and explore the feasibility and effectiveness of potential solutions. According to our quantitative and qualitative analyses, the problem of peak load discharges in the sector can be explained by the strategic behavior of wine producers in the context of enforcement deficits, as well as by particularities of the wine production process, and controversies around the construction and management of public treatment plants. Coordination among wine producers and public treatment plant managers to invest in in-house treatment infrastructure or to smooth discharges out so they fit the capacity of treatment plants would be a promising solution; however, economic incentives and tightened enforcement of discharge regulations would also be necessary. Graphical abstract Networks ofAction Situations inSocial‑Ecological Systems Research Handled by Christian Kimmich, Institut fur Hohere StudienInstitute for Advanced Studies, Austria. Extended author information available on the last page of the article 202 Sustainability Science (2023) 18:201–218 1 3 Keywords Networks of action situations· Point-source pollution· Winery· Wine industry· Wastewater· Aragon (Spain, EU) Abbreviations AS Action situations BOD5 Biological oxygen demand (in mg O2/l) CHE (in Spanish) Ebro Water Agency CLC Corine Land Cover COD Chemical oxygen demand (in mg O2/l) DGA (in Spanish) General Council of Aragon ECODES Ecology and Development ESM Electronic Supplementary Material EU European Union FNCA (in Spanish) New Water Culture Foundation GIS Geographic Information System IAA (in Spanish) Aragonese Water Institute IAD Institutional Analysis and Development IAEST (in Spanish) Aragonese Statistics Institute ICA (in Spanish) Water pollution tax INE (in Spanish) National Statistics Institute NAS Networks of action situations OECD Organisation for Economic Cooperation and Development PASD (in Spanish) Aragonese Sanitation and Purification Plan PDO Protected designation of origin PGI Protected geographical indications SDGs Sustainable Development Goals TN Total nitrogen (in mg/l) TP Total phosphorus (in mg/l) TSS Total suspended solids (in mg/l) UWWTD Urban Wastewater Treatment Directive WFD European Water Framework Directive WWTP Wastewater treatment plant ZINNAE (in Spanish) Cluster for the efficient use of water Introduction According to Target 6.3 of the Sustainable Development Goals (SDGs) by 2030, we need to “improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally”. The reality, however, is far from this goal. According to some estimations, only 32% of wastewater worldwide receives some type of treatment (Habitat and WHO 2021; Sato etal. 2013). The European Union has been a leader in the implementation of the SDGs and in ensuring the sustainability of water systems (EEA 2018; Ritchie and Mispy 2018; Niestroy etal. 2019; Tsani etal. 2020; Kurrer 2021). The European Water Framework Directive (WFD) (EC 2000) represented a milestone in the regulation of wastewater discharges and treatment in the continent; however, well-known compliance issues remain, including issues associated with point-source pollution from agglomerations and industries. In Spain and other countries, these issues have mostly to do with compliance deficits during peak discharge periods. Understanding why polluters fail to comply with environmental regulations is challenging. This article proposes to explore the causes and processes of compliance failure through an analysis of governance in the Spanish context. Many authors have looked at water problems through the governance lenses and highlighted the importance of, e.g., administrative fit between EU and national regulations (Borzel 2000; Ptak etal. 2020), coordination gaps across governance levels (Zikos and Bithas 2006; Vinke-de Kruijf etal. 2009), or local collective action challenges (VillamayorTomas etal. 2019; Dennis and Brondizio 2020). In this paper, we explore the extent to which incentives to comply with discharge regulations depend on strategic decisions made by both polluters and public authorities about wastewater production and treatment. The research questions that guide the article are: Which technological, financial, and institutional constraints shape wastewater production, treatment, and discharge decisions by polluters? How are those decisions interrelated? Which solutions along the production–treatment–discharge chain might facilitate compliance with discharge requirements? To address these questions, we rely on the networks of action situations (NAS) approach (McGinnis 2011a;Pahl-Wostl etal. 2010), which understands the behavior of resource users as being interdependent and embedded in decisionmaking situations (action situations, ASs) that are interconnected. Also, we focus on the case of the wine production industry in the region of Aragon, which is well known in Spain for facing problems of discharge irregularities and the overloading of public treatment plants. To analyze the 203Sustainability Science (2023) 18:201–218 1 3 case, we use quantitative and qualitative data obtained from interviews and public wastewater treatment data. In the next three sections, we further contextualize the case and introduce the NAS approach (see also Electronic Supplementary Material) and methods, respectively. In the subsequent sections, we introduce and describe the ASs that are key to understanding the governance of wastewater treatment in the case, and we explore the feasibility and effectiveness of potential solutions, respectively. Case background Point-source pollution from the agri-food industry, and the wine industry in particular, have been less of a public concern than diffuse contamination from agriculture in Aragon. However, this may change in the future, given the recent Fig. 1 Map of the Ebro basin (black contour), Aragon region (brown contour), showing (details in the text and note): wine areas (yellow and orange with transparency), agricultural irrigated areas (turquoise), vulnerable water masses and areas (red, purple and pink) and key municipalities (marked with arrows). Note: As detailed in the legend, the figure shows the wine Protected Geographical Indications (PGI) and the most important protected designation of origin (PDO) in the Ebro basin (thick black contour) and the region of Aragon (in thick brown contour). PGIs and PDO, represented in light yellow and orange, respectively (with transparency), overlap with groundwater masses in poor chemical status (red areas) and with nitrate vulnerable and sensitive zones (indicated in purple and pink contour lines, respectively). Many of the vulnerable and sensitive areas coincide with large agricultural farming (see in turquoise also particularly the important agricultural irrigated areas, typically of more production intensification). For example, the municipality of Ejea is covered by a PGI, which overlaps with nitrate vulnerable zones and underground masses in bad chemical status. The municipality of Calatayud falls within a PDO which overlaps with an underground mass in bad chemical status. Source: Own elaboration based on data from the Ebro Water Agency (CHE), Aragonese Statistical Institute (IAEST) and National Geographic Institute 204 Sustainability Science (2023) 18:201–218 1 3 promotion of large agri-food projects in some municipalities, and the expansion of the wine industry into areas that already suffer from diffuse pollution. Figure1 shows in different colors the wine Protected Geographical Indications1 (PGI) and the most important protected designation of origin2 (PDO). These areas (indicated in yellow and orange, respectively) overlap with groundwater masses in poor ecological status (red areas) and with nitrate vulnerable and sensitive zones3 (indicated in purple and pink contour lines, respectively; see note on Fig.1 for more details). The wineproducing industry is highly concentrated in five regions, which represent more than 80% of employment in the sector in Aragon (Zaragoza, Cariñena, Somontano de Barbastro, Campo de Borja and Calatayud; the last four being PDO regions, see GA 2010; Duarte etal. 2012; Aragonesa de Consultoría 2016; IAEST 2020). The main regulatory and planning instruments for wastewater treatment in Aragon are the Aragonese Sanitation and Purification Plan (PASD) (BOA 2009), and regulations governing wastewater discharges in municipal networks (BOA 2004, 2018a, b).4 The positive impact of these instruments in the region is evident. From 2005 to 2019, the number of treatment plants in Aragon almost quadrupled. Furthermore, the concentration of pollutants from urban point sources has decreased and the water quality of discharges from many treatment plants in the region have improved (GA 2021). Still, the ability of small municipalities to cope with occasional discharges coming from seasonal tourism or industrial activities remains a concern. Presently, around 200 (27%) of the 731 municipalities in Aragon rely on a Wastewater Treatment Plant (WWTP). Some municipalities have more than 1 WWTP, but many, especially small ones, have none. In the agri-food sector, 65% of the 199 municipalities within PGIs, and 72% of the 120 municipalities within PDOs, did not yet have a WWTP in 2019 (this number is near the average of 73% of municipalities in all Aragon without a WWTP5). In addition, some of the WWTPs have limited capacity. Discharges from wine producers and other activities are highly seasonal, and treatment plants, particularly those located in relatively small agglomerations, are not always able to guarantee optimal treatment during peak load discharges. According to the Aragonese Water Institute (IAA), which is the main entity managing wastewater treatment plants in the region, average concentrations of pollutants (see note to Fig.2) beyond standard limits are very infrequent, or nonexistent. Statistics show that many WWTPs have exceeded in at least one month per year (maximum month) the pollutant load levels for which the WWTPs were designed (see bubbles that are > 1 in Fig.2). This is particularly relevant in WWTPs that process large amounts of wastewater (see large size bubbles in Fig.2), like those located in Ejea, Calatayud, and Alcañiz. The NAS approach The NAS is an approach to study governance. Governance analysis focuses on understanding whether and how governments, agencies, companies, and other governmental and non-governmental organizations coordinate to manage public goods (such as wastewater treatment). The NAS approach builds on the Institutional Analysis and Development (IAD) (Ostrom etal. 1994; McGinnis 2011a, b), which is widely recognized as one of the leading frameworks in the policy sciences (Weible and Sabatier 2018) and governance studies (Poteete etal. 2010; McGinnis 2011b; Cole etal. 2019). At the heart of the IAD framework is the AS, an abstraction of decision environments in which individuals and/or organizations make decisions that affect each other and, potentially, broader groups. A look at environmental problems through 3 Directive 91/676/CEE of December 12, relative to the protection of waters against contamination produced by nitrates used in agriculture (Nitrates Directive), imposes on the Member States the obligation to identify the waters affected by contamination by nitrates of agricultural origin. It establishes criteria to designate vulnerable areas, as those territorial surfaces whose drainage gives rise to nitrate contamination, more specifically in the cartography compiled here from the National Geographic Institute, when the concentration of nitrates in water is greater than 50mg/l. It is considered a sensitive area, where water is at risk, when the concentration of nitrates is between 40 and 50mg/l. These identified areas are included in the Register of Protected Areas of the Basin Hydrological Plans. 4 These are in turn based on the European Urban Waste Water Treatment Directive (EC 1991). 5 According to the data, the Population (of 2019) served by the 188 WWTP managed by the IAA is 430,000 people (32% of the population of Aragon in 2019). We may add the handful of municipalities with a WWTP not IAA managed, with only one large municipality (actually the largest), Zaragoza, with 675,000 people. By adding these, it becomes 84% of the population of Aragon served by a WWTP. Hence, most of the municipalities without WWTP are relatively small (in population). The quite small municipalities (with barely a few dozens of inhabitants) either do not have a treatment plant or they are municipal septic tanks (not accounted in the WWTP data) which tend to lack maintenance. There are no large water-polluting effluents in municipalities not covered by a WWTP. Still, medium-sized municipalities of a few hundreds of inhabitants are more of a problem, since although they may have a sewage treatment plant, they do not have nitrogen and phosphorus treatment (only mandatory for more than 1000 equivalent inhabitants, with the existing many municipalities—86% of the total—having less than 1000 inhabitants). Eutrophication, especially due to nitrogen, is the main problem. 1 These are drawn in yellow (30% transparency): Bajo Aragón, Ribera del Jiloca, Valdejalón, Valle del Cinca, Ribera del Gállego-Cinco Villas and Ribera del Queiles. 2 These are drawn in orange (30% transparency): Cariñena (also with the municipality of Cariñena in gray), Calatayud, Somontano (also with the municipality of Barbastro in dark green) and Campo de Borja. 205Sustainability Science (2023) 18:201–218 1 3 the lenses of AS allows limiting a problem to a particular set of actors and their decisions, as well as to the social, biophysical and institutional circumstances that shape those decisions (see Fig.5 for a visualization of the ASs within the IAD framework). Environmental problems are complex and usually involve several interconnected ASs. The NAS approach provides methodological guidance on how to analyze multiple ASs systematically (McGinnis’s 2011a; Kimmich 2013; Kimmich and Villamayor-Tomas 2019). The “focal AS” is the situation most directly related to the outcome/s of interest (McGinnis 2011a). Once the focal AS is identified, the network is built by adding situations that can have an influence on the focal situation and on each other (Kimmich and Villamayor-Tomas 2019). Links between two situations occur when physical flows (e.g., of water), information or rules/policies emerging from one situation affect the behavior of actors in another situation (Kimmich 2013; Hoffmann and Villamayor-Tomas 2022, in this issue). Here, we rely on the NAS approach for two reasons. First, the approach is instrumental to our interest in looking beyond the wastewater discharge decisions of polluters. Important decisions that polluters make other than discharge decisions may include, for example, wine production Fig. 2 Ratio between the load treated in the maximum month and optimal treatment load (both in terms of equivalent inhabitants) for several Wastewater Treatment Plants (WWTPs) in Aragon. Notes: The size of the bubbles reflects the size of the (average) load treated in the maximum month in each WWTP. Each color represents one of the 188 different WWTPs. Ratio > 1 indicates overload of the WWTP at some point in the year. According to the IAA, the main indicators of wastewater overloads are total suspended solids (TSS), biological oxygen demand (BOD5), chemical oxygen demand (COD), and, in sensitive areas, total nitrogen (TN) and total phosphorus (TP). The size of the bubbles reflects the size of the (average) load treated in the maximum month in each WWTP (measured in terms of equivalent inhabitants). Data corresponding to 188 WWTPs are illustrated [the most recent information suggests that there are around 220 WWTPs in Aragon (some are managed by companies in service contracts and through concessions)], and the data has been available since 2005 (many municipalities began to have WWTP and data from 2008– 2009, illustrating similar values). Note also that the data refers only to municipalities with WWTPs. The Supplementary Material provides the original data. The optimal treatment load is defined as the design treating volume. As explained in full in IAA (2019), the criteria for obtaining the design volume is described in the Zonal Plans, in the projects that develop them, and in the Guidelines, General Urban Planning Plans, Partial Plans and instruments that develop them. The theoretical influent flow will be calculated by applying the following criteria: urban unit endowments, industrial unit endowments, livestock unit endowments, current average demand, current peak demand, future average demand, estimate of the inflow to the treatment plant. Source: Own elaboration from Open data IAA-Government of Aragon (GA 2022) 206 Sustainability Science (2023) 18:201–218 1 3 decisions and decisions about whether to invest in in-house treatment devices. The NAS approach can not only assist in the identification of those decisions, but also the analysis of how they influence wastewater discharge decisions. From the NAS approach perspective, polluters’ decisions are interdependent6 and shaped by incentives (i.e., costs and benefits) that can be evaluated. Second, the NAS approach can help in ex ante policy evaluation (Kimmich and Villamayor-Tomas 2019). Interventions aiming at correcting undesirable outcomes in one situation can be assessed with regard to (1) their indirect impacts on other ASs and (2) their ultimate ability to improve final outcomes. Here, we use the NAS approach to evaluate ex ante actions that could modify untreated wastewater discharges by wine producers. Our review of the literature suggests that this is the first study that applies the NAS approach to the point-source pollution context (see also Kimmich etal. 2022, in this issue). Thus, we believe a first contribution of this study consists in the specification of key important ASs and their linkages in this context. We expect our study serves as a reference for similar ones in the future. This is not trivial because the IAD (and NAS approach) has been used to understand natural resource management problems (e.g., irrigation water use appropriation, monitoring, or infrastructure maintenance; Villamayor-Tomas etal. 2015), but not pollution problems. Also, our analysis contributes to illustrate the use of the NAS approach for ex ante policy analysis. Contrary to previous efforts (Kimmich and Villamayor-Tomas 2019), we assess the feasibility and effectiveness of policies that have actually been proposed by public authorities and stakeholders. Last but not least, this study combines qualitative and quantitative information in a systematic and meaningful way. In our understanding, few of the involved actors in this case had a full picture of the pollution problem and this had to do with the lack of quantitative and qualitative syntheses like ours. Methods Although there is no clear protocol about how to draw boundaries of ASs, some patterns start emerging in the literature (Kimmich etal. 2022). As hinted in the previous section, a common strategy is to first identify the focal AS and then observe the incentives7 of actors that make decisions in that situation. In our study, the main concern among interviewees was the mismatch between wastewater discharges by wine producers and the capacity of municipal wastewater treatment plants to treat those discharges. A majority of the interviewees referred to the lack of on-site water treatment devices by wine makers as the most direct cause of such mismatch. Thus, we took this situation as the focal situation and named it as the “Upstream Treatment” situation (AS2). Then, to populate the NAS we followed the value chain of wastewater production, treatment and discharge stages, each of them potentially representing an AS.8 Additionally, we observed key governance/managerial tasks associated with pollution treatment and control that could affect the on-site wastewater treatment situation (McGinnis 2011b). To characterize incentives within each AS, we observed material, socio-economic and institutional conditions (Oberlack etal. 2018; Kellner and Brunner 2021). In terms of material conditions, we looked at quantitative data on the chemical status of water and the financial constraints of installing on-site wastewater treatment devices.9 Regarding social conditions, we looked qualitatively at features of the winemaking industry in the area (including size, business type, or financial conditions), as well as the heterogeneity of interests among polluters and public authorities around wastewater treatment and enforcement. Institutionally, we collected qualitative information on existing rules (formal laws and regulations, subsidies for wastewater infrastructure provision), shared understandings regarding water use priorities, and informal standards and expectations about wastewater discharges and their timing. We obtained quantitative data (on discharges and treatment, see Fig.2; and location of wine producers, see Fig.1) from public websites and data repositories (CHE 2021; GA 2021; IAA 2021b). Qualitative data were obtained from secondary documents (e.g., GA 2021; MAPA 2021; BOA 2004, 2018a, b) and interviews with key stakeholders, among other sources (see Table1 in the Appendix). We interviewed 25 key informants from October 2020 to May 2021. Interviews addressed representatives of the main water governance organizations in the region (see Albiac etal. 2014; Bielsa and Cazcarro 2014; CESA 2003). We interviewed representatives of the Ebro Water Agency (CHE)10 board, the Aragonese Water Institute (IAA), key agri-food and wine 7 By incentives, we refer to the costs and benefits that affect individual and collective decisions, i.e., of wine producers and public authorities in a particular AS. For example, constraints that may shape incentives to, e.g., install on-site wastewater treatment plants by wine producers include the financial costs of those devices and the effective enforcement of discharge regulations. 8 See Villamayor-Tomas etal. (2015) and Oberhauser etal. (2022) for other applications of the value chain heuristic to identify AS. 9 On the cost of urban wastewater treatment in the South of Spain, see Pajares etal. (2019). 10 The CHE has traditionally been the main water management authority in the Ebro River basin. This basin is the main one within the region of Aragon, and most of the rivers in the region flow into it. 6 Wine producers are interdependent in the compliance/pollution emission decision, because as more wine producers control their emissions the need that others comply decreases. 207Sustainability Science (2023) 18:201–218 1 3 clusters, wine producers, farmers’ (irrigation) communities, the Cluster for the Efficient Use of Water (ZINNAE), and key wastewater treatment businesses and managers. Additionally, we interviewed researchers who were experts in the matter. Interviews were semi-structured and included questions about the history of wastewater treatment in Aragon; main management barriers or challenges; key agents/stakeholders “responsible” for the challenges; knowledge and opinion of other views, arguments, challenges, etc.; and solutions and their feasibility. Results In our analysis, we found the lack of upstream wastewater treatment capacity (or use) of wine producers as the focal AS (AS2). The wastewater is generated by wine producers (and depending on the context, especially in urban areas, also by other businesses), AS1. Two directly connected situations are: AS4—water pollution and overloads at the WWTPs from wine producers’ discharge regimes (the detection of those overloads being the main warning of water treatment challenges); and AS6—wastewater treatment enforcement, which requires paying attention to the incentives and constraints of monitoring agents. The building and maintenance of treatment plants (AS3) allow us to explain the case with an eye on the historical development of the wastewater treatment industry in the region. Finally, the potential downstream incompliance is studied in relation to the regulations/enforcement and environmental harm (AS5). Figure3 shows the spatial location of ASs. We identify these ASs individually in “ASs”, the full network in “The NAS”, and the appraisal of potential interventions in the "Discussion" section. ASs AS1: wastewater production The wine-producing industry in Aragon has four important particularities connected with wastewater pollution. First, as indicated by the main representative of the agrifood (and wine industry) cluster, wine producers require high-quality water as an input for the production process. Second, and most importantly for us, the wine production process needs water for cleaning purposes. This water constitutes the main source of discharges and can be quite irregular throughout the year. The peak of discharges occurs during ‘the vintage’, which lasts around 3months. After the vintage, the production process is less intense, but more irregular. It concerns the racking of wine and cleaning of deposits. These operations can discharge significant volumes of pollutants in very short periods of time, sometimes within one day, and can be more problematic to manage than vintage-related discharges. Third, as highlighted by the Head of the Water Quality Area of the CHE, although average loads from wine producers are not Fig. 3 Action situations (AS) associated with the schematic and spatial view of water intake, pollution and treatment flows. Note: The blue boxes indicate the wastewater treatment plant, the wine related discharges and “other discharges” (from industry, services, households, etc., which often are all gathered in collectors before reaching the plant). The red boxes try to approximate in space the places where the ASs mainly occur. WWTPs: wastewater treatment plants. Source: Own elaboration 208 Sustainability Science (2023) 18:201–218 1 3 particularly high (as compared to pig farms, for example), they can be highly polluting. Water has a low pH and high sulfur, sodium and organic matter concentrations, all of which can severely threaten the eutrophic balance of rivers and aquifers, or affect/destroy the WWTPs’ biological systems. Fourth, the wine sector enjoys a strong tradition and has significant economic weight in Aragon, albeit at a small scale, relatively atomized, and geographically dispersed (see also ESM for more details on each of these four aspects). AS2: capacity anduse ofin‑house/upstream wastewater treatment Given the peri-urban location of many of the wineries, most of the discharges flow into municipal sewage systems or collectors connected to them. As highlighted by legal academics and WWTP managers, even if municipalities have wastewater treatment plants, the legislation requires that any polluter, including wine producers, install in-house treatment facilities when COD discharges are expected to go beyond 1500–2000mg/l. However, as recognized and identified both by wine producers and wastewater treatment managers, producers are quite resistant to making these investments. They are considered as non-productive investments that jeopardize producers’ returns and, in some cases, their capacity to break even. Treatment costs depend on technologies, but are seen as high given the small scale of producers. Biological treatment, which is the cheapest option in terms of operational costs, faces high upfront costs due to the required water storage and retention infrastructure. Indeed, some producers may not have the financial resources, or space (e.g., water storage capacity), to install the treatment equipment within their premises, involving around 100,000–150,000 € on average (according to the wastewater treatment businesses and winemakers). Moreover, wine industry wastewater production is very seasonal, but the biological treatments require continuous maintenance throughout the year for proper performance. This could be seen as a waste of resources, given that the infrastructure is not regularly used (for further details on the costs and technologies, see the ESM). In terms of in-house treatment facilities, there are a few large, very localized producers in Aragon who have invested in, and use, their own systems, e.g., Viñas del Vero in the Municipality of Barbastro and Bodegas San Valero in Cariñena. Outside the wine sector, the pulp industry is characterized by very large and spatially concentrated companies, all of which include in-house treatment facilities. Large, localized firms can afford research and innovation investments and enjoy scale economies, all of which can ultimately reduce treatment operating costs. However, this is not generalizable to most wine producers in the region due to their small scale, unless they pool resources. AS3: building wastewater treatment plants By default, the municipalities are responsible for wastewater treatment in the region. However, in the 1990s many delegated this responsibility to the IAA, due to their lack of financial capacity to build and operate the plants (for further information on this and the role of the EU, see the ESM). The PASD, approved by the regional government (General Council of Aragon, DGA in Spanish) in 2001, organized the financing and construction of plants that would be managed by the IAA and set standards for all others. As indicated by IAA managers, the regional governments imposed a new water pollution tax (ICA in Spanish) to all the affected municipalities (GA 2019; IAA 2021b) to finance the WWTPs construction and operation. Indeed, nowadays the IAA obtains 90% of its budget (70 million euros) from this tax. Currently, few plants in the region are managed by the municipalities themselves and 220 are managed by the IAA (IAEST 2021a), a public agency dependent on the DGA. The implementation process has not been entirely smooth. Some municipalities complained about pressure from the IAA to delegate the management in exchange for financing. Furthermore, there have been complaints about the public–private management model used by the IAA to operate the plants and collect the ICA (a tax with a highly disputed social response; see Lisbona 2021, which is to be replaced) and the preference given to multinational firms over public management. The PASD was supposed to be reassessed every 6years; however, the first revision took place in 2009. In 2015 the government initiated an evaluation that was never finalized, and in 2017 organized a participatory process to reform it. AS4: operations andmaintenance ofmunicipal/ downstream wastewater treatment plants Most of the systems used in municipal wastewater treatment plants rely on activated sludge biological treatment technologies, which are considered more robust against peak loads. In particular, according to the most up-to-date data, 82% of the WWTPs rely on activated sludge with some other combination of treatment (e.g., 77% of the total have activated sludge in prolonged aeration; IAEST 2021b; see also the type of treatment in each municipality, column X of tab “Data for Ratios” in the ESM). Peak discharges are not a problem in large municipalities that have large capacity treatment plants that are able to cope with very large and polluting discharges. Municipal governments are generally able to absorb overloads and to sanction producers for not 209Sustainability Science (2023) 18:201–218 1 3 having in-house treatment facilities. Imposing the installment of those facilities on producers would not only be a waste of resources, but would also prevent municipalities from gaining the extra income obtained from sanctions. (See also enforcement situation.) The real issue (highlighted by several interviewed agents) emerges when producers and municipalities are small (i.e., the WWTPs). For example, in small municipalities within a wine area (say, e.g., Longares in Cariñena or Miedes in Zaragoza), the main wine industries (that employ around 25 people) produce relatively high-quality wine for export. The municipal sewage treatment plant is designed for only 500 or 1000 inhabitants in the village, so that when the wine producer hits a certain level of discharges, it surpasses the figure for equivalent inhabitants. This, at best, can decrease the efficiency of the WWTP and, at worst, overflow its capacity. The wine producer should therefore install in-house treatment equipment or be fined. Theoretically, the fine for not treating wastewater is higher than the treatment investment itself. However, fines may not be sufficiently discouraging if the wine producer considers the occupied (productive) space, the difficulties with storing water, the operational costs of treating the water and the need to treat non-storable volumes. We may add the fact that pollution limits are measured as concentration (g/ml), which creates incentives for wine makers to dilute the effluent. Moreover, producers at small municipalities must comply with the same concentration limits as those generating larger discharges (in absolute terms). Producers are often not capable of reaching the required concentration limits despite having low or no WWTP capacities and small discharges that are generally not dangerous to the environment. As a result, producers are more likely to be fined generating frustration and feeling of unfairness among producers. AS5: enforcement ofdownstream wastewater emissions The enforcement authority of wastewater emissions is shared between the CHE, the IAA and municipal authorities (Arrazola Martínez 2013). The CHE was originally the main authority until the approval of the Aragonese Sanitation Plan. Since then, the CHE has been responsible for direct discharges, while the IAA and the municipalities have been responsible for indirect discharges (i.e., discharges that are collected from various wastewater sources), including those from wine producers. Enforcement of wastewater treatment regulations involves two different sets of actors and, indeed, two different dynamics, depending on whether it applies to upstream (in-house, wine-producing plants) or downstream (WWTP) treatment plants. Thus, we conceptualize enforcement as involving two situations, considered here and in the next subsection (AS6). The main enforcement authority of downstream discharges is the CHE, whose responsibilities have included water quantity and quality. The CHE (which also supplies the data for the National Census of Discharges; MITECO 2021) has an inventory of authorized direct wastewater discharges, including those from WWTPs (CHE 2021). Based on these data, one can observe that the largest yearly volumes (of authorized entities) are: the Industrial Refrigeration of the Nuclear Ascó-Vandellós II plant in Tarragona (1651 hm3/ year), several industrial fish farms (all below 160 hm3/ year) and urban or similar type installations with more than 50,000 habitants-equivalent discharges (typically in cities, all below 60 hm3/year, including Zaragoza, Pamplona, Vitoria-Gasteiz, Lleida and Logroño). To obtain authorization, discharges need to fulfill standards of maximum pollutant concentrations according to the Urban Wastewater Treatment Directive (UWWTD) and the Drinking Water Directive. For most of them this means ensuring proper treatment. In turn, authorized discharges must comply with daily and annual load limits and rely on a self-managed registry of discharges and water quality measurements that are shared regularly and on-demand with the CHE. Furthermore, polluters need to pay a pollution monitoring fee depending on the discharge volume, the environmental conditions of the affected water system, and whether it is industrial or urban. The fee is used to protect and improve the water system. Last but not least, the CHE relies on a series of measurement stations within the basin to regularly collect water quality data and to flag transects within the Ebro River subjected to occasional high pollution concentrations. In terms of interactions, the CHE can impose sanctions on non-authorized discharges or authorized discharges that do not comply with the standards. The CHE has acquired a reputation for being quite inflexible in sanctioning firms and municipalities, especially those that do not have treatment plants in place. Sanctions on these municipalities have created conflict with the CHE, as most municipalities had delegated the construction of their treatment plants to the IAA, but were still without them. In 2018, in recognition of the conflict, the CHE approved a moratorium on sanctions for those municipalities that continues today. AS6: enforcement ofupstream wastewater emissions By default, municipalities have the authority to monitor indirect discharges, e.g., those flowing from wine producers into urban sewage systems and the WWTPs (where they exist). However, very few municipal governments have articulated this responsibility with regulations. Additionally, the IAA self-assigned the responsibility to manage WWTPs under its jurisdiction (i.e., delegated by the municipalities; BOA 2004). Based on this assurance, the ambition of the IAA is to run regular inspections. However, these inspections are 216 Sustainability Science (2023) 18:201–218 1 3 included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/. References Albiac J, Calvo E, Esteban E (2014) Chapter9: river basin governance and water policies in Spain: managing water in multi-layered political systems. In: Garrick D, Anderson GRM, Connell D, Pittock J (eds) Federal rivers. 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Authors and Affiliations IgnacioCazcarro1,2 · SergioVillamayor‑Tomas3· MariaPilarLobera4,5· JoaquínMurría6· MaríaBernechea1,4,5 * Ignacio Cazcarro [email protected] 1 ARAID (Aragonese Agency forResearch andDevelopment), Government ofAragon, Av. de Ranillas 1-D, planta 2ª, oficina B, 50018Zaragoza, Spain 2 Department ofEconomic Analysis, Agri-Food Institute ofAragon (IA2), University ofZaragoza, Gran Vía 2, 50005Zaragoza, Spain 3 Ramon y Cajal Research Fellowship attheInstitute ofEnvironmental Science andTechnology (ICTA-UAB), Autonomous University ofBarcelona, Barcelona, Spain 4 Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Department ofChemical andEnvironmental Engineering, University ofZaragoza, Campus Río Ebro-Edificio I+D, C/ Mariano Esquillor S/N, 50018Zaragoza, Spain 5 Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina, Instituto de Salud Carlos III, 50018Zaragoza, Spain 6 INGEOBRAS S.A., C. Madre Rafols, 2, 50004Zaragoza, Spain