Applying a Social-Ecological System Framework to the Study of the Taos Valley Irrigation System
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- Cox, M. Hum Ecol (2014) 42: 311. doi:10.1007/s10745-014-9651-y
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This paper applies a social-ecological system (SES) framework to the analysis of a SES in the Taos valley of northern New Mexico. The SES analyzed is a set of interconnected irrigation communities known as acequias. These have persisted in the area for several hundred years. In this paper I combine concepts from multi-level governance, social network analysis, and interconnected action situations to diagnose the factors that have enabled the acequias to maintain the levels of cooperation needed to persist as farming communities in a high desert environment. To conduct this research, interview data were collected on-site to complement existing court testimonies and other relevant primary and secondary data. These data were analyzed via a step-wise diagnostic process that is inspired by the SES framework and used to illustrate how the acequias form a multilevel governance system via key network attributes, and how this governance structure maps onto the resource system while not overburdening the participants and providing sufficient benefits to motivate continued cooperation over time.
KeywordsSocial-ecological systems Acequias Irrigation Diagnosis New Mexico Institutions
Small-scale irrigation systems are important for at least two reasons. First, the majority of the world’s poor depend on small farms for their livelihood, and most of these farms employ irrigation (Anderies and Janssen 2011). Secondly, many of these systems offer an opportunity to better understand ways in which humans can sustainably interact with their natural environment over long periods of time. As such, small-scale community-based irrigation systems have become one of the iconic examples of sustainable small-scale environmental management (Ostrom 1990).
However, the literature on community-based common-pool resource (CPR) management, and the closely associated literature on social-ecological systems (SESs) have several weaknesses. First, biophysical features that contribute to outcomes (e.g., Lam 2001; Tucker et al.2007) are often underemphasized, and relationships between the independent variables that affect outcomes are insufficiently examined (Agrawal 2001, 2003). Second, the roles played by multilevel governance structures and social networks in natural resource management (Berkes 2007; Brondizio et al. 2009; Janssen et al. 2006; Lauber et al. 2008) are rarely combined to explore how the network structure of resource users can create nested levels of governance that manage successively large extents of a resource system. And finally, there are few empirical analyses that have attempted to formalize how a process of diagnosing SESs would look when applied to a particular system (Ostrom 2007, 2009).
In this paper I attempt to address these gaps in the literature via a case study analysis of the acequia irrigation systems of Taos Valley, New Mexico. The acequias1 in the Taos Valley, like others in New Mexico, have sustained themselves as self-sufficient irrigation systems for hundreds of years by adapting to high desert conditions and inevitable periods of drought. They are now facing the threats of economic development, changing demographics, dissonance with the state-level water management perspective, and the penetration of water markets. This study focuses on the institutional and biophysical properties that have enabled them to historically persist in the face of material scarcity, leaving the question of their resilience, or vulnerability, to modern disturbances in the modern era for a subsequent paper.
A CPR, such as a forest or a fishery, has two defining characteristics: subtractability, i.e., one user’s consumption subtracts from what is available to others, and the high cost of exclusion, i.e., the difficulty of imposing obligations on users or preventing outsiders from consuming the resource (Ostrom et al.1994). To sustain the acequias over time, users must resolve the collective-action problems inherent in the divergence between individual and community-level interests created by these characteristics.
The first collective-action problem is the challenge of motivating individuals to forego excessive consumption of a subtractable resource, in this case water. For example, if one user diverts water to irrigate his or her fields, this water will be unavailable to users downstream of his or her fields. Secondly, there is the challenge of motivating individuals to contribute to the physical and social infrastructure that makes appropriation possible and excluding non-contributors from benefiting from the efforts of contributors.
Models of Human Behavior
Understanding how collective-action problems may be resolved depends on an understanding of human behavior. I adopt a model of human actors based on existing literature (Jones 2001; Ostrom 2005; Poteete et al.2010) that includes the following properties: (1) actors exhibit bounded rationality, with limitations on their ability to perceive, process, and recall information; (2) actors are self-interested, frequently valuing personal costs and benefits over social costs and benefits; (3) actors are highly socialized with preferences for equity and reciprocity, adherence to group norms and social pressures, and with high capacities for cooperating in small groups. Furthermore, the benefits achieved by an individual for his or her cooperation are a function of the extent to which other actors cooperate. Thus, an actor’s expected benefits rise if he or she can be assured that others will reciprocate his or her cooperation. In these situations we can expect many actors to behave as conditional cooperators, reciprocating the behavior of others. If the benefits expected by an actor are high enough, we can predict that he or she will cooperate, which in turn raises the expected benefits of other actors, who will reciprocate to create a self-reinforcing cycle of cooperation. Self-reinforcing cycles of non-cooperation are likewise possible.
However, making initial agreements and subsequently monitoring and enforcing rules to limit rule breaking incur transaction costs. If these are too high, they can overwhelm the benefits of collective-action. Thus, the challenge is to adopt a set of social features that fit with a particular biophysical environment to provide the benefits needed to maintain a degree of cooperation while avoiding excessive transaction costs.
Social Networks and Multilevel Governance
In order to understand how acequia communities address these collective-action problems I combine two perspectives: multilevel governance and social networks. A network is a system composed of nodes and the links that connect these nodes. Typical network analyses collect data on nodes and links and calculate statistical properties that summarize the distribution of links among the nodes. Social networks are networks with individual or collective human actors as nodes. In the analysis of social networks in the context of CPR and environmental management, the links between these nodes are normally defined as those interactions that directly affect CPR outcomes. Examples include routine interactions among actors regarding environmental policy issues (Schneider et al.2003), exchanges of information regarding a natural resource, fishing gear exchanges, and social support activities (Bodin and Crona 2008), and exchanging ideas and funds (Lauber et al.2008). The definition of nodes and links is highly specific to the research question being addressed. Multiple levels of organization, meanwhile, have been thoroughly established in many long-lasting community-based irrigation systems (Coward 1977, 1979; Geertz 1959; Siy 1982). A system with multiple levels of governance has management activities carried out by different sets of actors at different spatial scales. Generally levels associated with smaller spatial scales are nested within other levels associated with larger spatial scales.
In this analysis I employ the Institutional Analysis and Development (IAD) and Social-Ecological Systems (SES) frameworks, the former of which has been used in meta-analysis of irrigation systems and fisheries around the world (Cox et al.2010; Ostrom 1990; Schlager 1990; Tang 1992), for irrigation systems in Nepal (Shivakoti and Ostrom 2002), and for studies of forests undertaken by the International Forest Resources and Institutions (IFRI) research program (Gibson et al.2000; Poteete and Ostrom 2004; Wollenberg et al.2007).
Study Area: The Acequias of the Taos Valley in New Mexico
The acequia farmers in New Mexico and in parts of southern Colorado are the descendants of the Spanish colonists who moved north along the Rio Grande from Mexico beginning around 1600. They brought with them several Spanish irrigation traditions, most importantly communal management of water and compliance with community obligations in order for an individual to maintain his or her individual water rights (McCay 1996; Rivera 1998). Thus, within each acequia, private-level rights are subject to communal rules and norms.
Each acequia has a well-defined system of governance, led by a mayordomo and three commissioners. The mayordomo decides how water is distributed within his or her acequia, monitors infractions and also oversees the annual canal or “ditch” cleanings each spring. The commissioners serve several administrative, legislative, and judicial roles and are frequently called on to arbitrate disputes and support the mayordomo in enforcing ditch rules.
The Taos acequias have a history of conflict over water, both within each community and between them. Over time, formal water-sharing agreements among groups of acequias (repartimientos) have been formed, usually with assistance from external government bodies. The governmental regime presiding over what is now New Mexico can be broken down into four periods: (1) the colonial or Spanish era, (2) the Mexican era, (3) the U.S. territorial era, and (4) the U.S. statehood era. Throughout these periods, the government, primarily in the form of local courts, played a crucial role in land settlement and arbitrating disputes amongst waves of settlers.
In the Spanish era, which began in the 1600s, there was a two-tiered conflict resolution mechanism for settlers and irrigators in the form of a provincial governor who appointed regional alcaldes. Mexican independence from Spain in 1821 led to several changes, including the transition from governance by local alcaldes to governance by ayuntamientos, who worked to resolve “allocation disputes between competing settlements, questions of priority, rights-of-way, acequias maintenance, and related problems” (Baxter 1997:32). In 1837, ayuntamientos were replaced by juezes de paz (judges of peace). Following the U.S. Mexican war in 1848, a new territorial government system was put in place including “an executive, a court system, and an elected legislative assembly” (Ibid:65). Within the court system, the local probate court became the most critical governmental body for resolving water disputes. Several decisions made by territorial probate courts stand today as formal repartimientos.
After World War II, the most influential government agency became the New Mexico Office of the State Engineer (OSE). This agency regulates all water in the state of New Mexico, running adjudications in each basin to account for each individual water right and the priority date assigned to it (in line with the doctrine of prior appropriation). This approach to water rights is in stark contrast to that of the acequia communities, which emphasizes the equality of different community water rights that are normally expressed in units of time rather than in specific amounts.
Data Collection and Analysis
Eight months of fieldwork were conducted in the Taos Valley. Data collected include a set of court testimonies outlining historic water-management practices of the Taos acequias.2 In the early 1990s, 36 senior acequia officers were called upon to testify regarding their traditional water management practices in the valley. The testimony data were validated with original on-site data collected through in-person interviews.
Thirteen interviews were conducted with acequia mayordomos and 30 interviews with acequia commissioners. These interviews, mostly informal and open-ended, generally took place in the residence of the respondent, and lasted an average of 2 h.
Data collected on the acequias were also used in a related statistical analysis that used all 51 Taos Valley acequias as the unit of analysis (Cox and Ross 2011) along with data from a series of hydrographic survey maps made between 1969 and 1971 by the New Mexico Office of the State Engineer (OSE), as well as a series of satellite images from NASA’s Landsat program and time series data from several stream gages in the valley maintained by the United States Geological Survey.
As mentioned earlier, data analysis for this study consisted in leveraging the available qualitative data to identify (1) the relevant components of the acequia SES, (2) the relevant action situations used by the acequias, and using Ostrom’s SES framework to unpack the important features that affected decisions made in these situations to explain important outcomes (see Appendix for details of data measurement and organization).
Results: The Social-Ecological Structure of the Acequias
The Biophysical Context
The harsh desert environment of the Taos acequias favors communal arrangements to cope with scarce resources. In this case, the motivation for communal management and the collective action it requires has been further strengthened by the historic economic poverty (A2a) of the irrigators and their extremely high historical dependence on the resource system (A8) as the only means of obtaining food.
The primary resource unit is water. While acequia members also have livestock that graze on pasture areas, in this analysis I focus primarily on the water unit. The livestock unit and the historic pasture lands that many acequia members used are historically important but were not managed as part of the traditional acequia water and irrigation governance regime, and much less information is available about how such lands were managed. Thus, for this analysis these will largely remain exogenous as a factor I recognize as helping the acequias persist and resolve the collective-action problem associated with water management.
Each resource system has one of the two defining principles of a CPR: high cost of exclusion (RS9), while the other defining property belongs to the water resource unit, which is moderate subtractability (RU8), meaning that once a farmer turns a quantity of water into his or her fields, it is unlikely, but not impossible, that this same quantity of water will be available to other farmers. Physical boundaries are clear for the irrigation system (RSI2), but unclear for the aquifers (RSG2). The boundaries for the land system are relatively clear at the parcel level but may have been substantially weaker for commonly owned pasture lands (RSL2).
While the water resource unit is moderately renewable (RU2), periods of scarcity are common. It is also highly mobile (RU1), and is highly heterogeneous in its spatial (RU7a) and temporal (RU7b) distribution. Spatial heterogeneity means that there is extensive variability in water availability across the valley. Regarding the temporal distribution of water, USGS (2010) stream gage data show that the amount of water that is available through surface runoff is highly variable intra- and inter-annually. Surface runoff through rivers is the source of the vast majority of water for the acequias, meaning that they face water scarcity on a fairly consistent basis.
There are several biophysical features of the acequias that moderate water scarcity. Hydrological work by Barroll and Burck (2006) and Drakos et al. (2004) indicates that the relationship between surface water and groundwater in the Taos Valley is quite strong, and that withdrawals from one affect the availability of water from the other (RSL10). Additionally, through hydrological analyses of acequia systems in other parts of New Mexico, Fernald et al. (2007) and Fernald and Guldan (2006) have found that acequia irrigation raises nearby water tables in an area they label the “irrigation corridor.” This is in part a result of the low level of technology (A9) employed by the acequia members—mostly shovels and sticks—to maintain irrigation canals that are earthen or unlined (RSI4a). Because they are unlined, these ditches allow water to percolate into the shallow groundwater aquifers.
In part due to the tight connection between surface and groundwater in the Taos Valley and the acequias’ unlined canals, the shallow aquifers in the valley store water after it has percolated down following streamflow and irrigation events (RSG8). This water frequently seeps back up to the surface for downstream farmers to use. Cox and Ross (2011) found that acequias with more irrigated land in the “irrigation corridor,” where higher water tables are more likely to make groundwater available, perform better over time. In fact, interviewees frequently reported the availability of water through seepage when the main stream or canal was dry during a drought (see Rodriguez 2007:47). This storage capacity is particularly important due to the high variability of the resource unit (RU7b) and low storage capacity (RSI8) for surface water (due to a lack of funds for reservoirs) that the Taos acequia members must contend with.
A second way that the acequia members moderate the subtractability and scarcity of the resource unit and augment downstream availability is through the use of desagues, or drainage channels (RS4Ib) that return unused flows back to the main river downstream of an acequia, ameliorating upstream-downstream conflicts over water. Finally, acequia farmers have historically ameliorated water scarcity by using a pasture system to augment the nutrients and energy that their agricultural crops provide them. Much of this pasture was historically on commonly held higher elevation lands outside of individually owned tracts. In an arid environment, pasture can be the most productive use of large amounts of land, as mobile livestock can graze on a large enough expanse to effectively make use of an amount of rainfall that otherwise would be too disbursed to allow for subsistence activities.
The Multilevel Governance Structure
The connections between these action situations have different significations. In the first level, the appropriation situation affects the provision situation by providing the water that is the source of the expected benefits that motivate individuals to incur the costs of maintaining irrigation infrastructure. The provision situation in turn affects the first-level appropriation situation by making the collection of these benefits possible. The appropriation situation at the first level can also affect the second-level appropriation situation when appropriation decisions by members of one acequia affect how much water is available downstream for a mayordomo to divert into the main headgate for his or her acequia. At the second level, mayordomos and commissioners affect the first-level situations when they determine how much water can actually be appropriated within each of their acequias.
How Acequia Members’ Social Network Structure Creates Multilevel Governance
Defining a single type of social link between the acequia farmers and measuring it at a particular point in time in the Taos Valley proved to be both misleading and impractical for this study. There are multiple ways in which the farmers in the valley interact, and it is the combination of these different types of interactions that forms their social structure. Still, based on available data, important qualitative descriptions of the acequias’ social network properties can be usefully presented.
The inferences about network properties discussed below are based on three different types of interactions, or network links: water appropriation/allocation activities, infrastructure provision activities, and monitoring actions. Based on interviews with acequia officials and a review of the court testimonies, these activities and types of interactions were judged to be most crucial in determining the outcomes of the collective-action situations. Each type of interaction can be considered as a separate social network operating within the acequias.
The acequias’ governance networks contain important degrees of centrality and modularity (GS3a and GS3b). Centrality can be defined as the presence of “some high-ranking nodes in the network that have a significantly higher-than average number of links and/or have links stretching from beyond their local network neighborhoods. Well-connected nodes, i.e. hubs, in the network, are most likely of higher importance than others that are not so well connected” (Janssen et al.2006). Mayordomos are extremely highly connected in each type of network. It is universal in the Taos acequias that the mayordomo is in charge of the water allocation process and has a connection to every member in their own acequia in this social network. Farmers either call the mayordomo when they want water or attend regular meetings where they receive their allotted time to irrigate. In both cases the mayordomo maintains a list of who has the right to irrigate and when they can. It is a rotationally based distribution system (GS5b), and users are given water rights in proportion to their land rights, which are distributed heterogeneously (GS4a).
Additionally, the mayordomo monitors the behavior of each one of the members within his or her ditch. The effectiveness of their monitoring is determined by their authority and local knowledge as the central distributor of water. Finally, the mayordomo is central in the infrastructure provision network, which is constituted by those interactions that acequia members engage in as they build and maintain the irrigation infrastructure. The earthen canals must be periodically cleaned of debris that naturally accrues in them. This activity generally occurs during an annual event called la limpia de la acequia (the cleaning of the ditch). The mayordomo is in charge of this annual event (see Crawford 1988). Obligations to contribute are proportional to the amount of water rights owned (GS5a), which maintains a sense of equity in spite of the uneven distribution of those rights.
Each of the previous activities occurs exclusively at the first level of governance within the acequias. At the second level, the mayordomos and the commissioners act as bridges between acequias in the second level appropriation situation. Collective-action problems between acequias are addressed through water sharing agreements, or repartimientos. Repartimientos are the result of past conflicts, and involve meetings between acequia officials (sometimes mayordomos, sometimes commissioners, sometimes both) in times of resource scarcity to affirm historically held agreements as to how water is to be divided up between them. Unlike the purely rotational system that dominates within acequias, the more standard model between acequias is to allocate proportional amounts simultaneously to each acequia. Not all acequias are involved in formal water agreements, and Cox and Ross (2011) show that those without water-sharing agreements are those with higher than average access to groundwater, which likely saves them from the need to work out differences over scarcity in surface water.
In a modular network, nodes cluster to form natural groups within which they are more highly connected than they are to nodes within other groups. Each of the acequias in the valley naturally forms a module in a larger network of relationships among the rest of the farmers in the valley. Much more intensive and regular interactions occur within acequias than between them. Less common but important connections exist between many acequias (primarily through their officers) that enable them to resolve collective-action problems on a larger scale through their repartimientos.
In addition to the mayordomo-led water allocation and provision activities, an additional source of intra-acequia interactions, and the system-level attribute of network modularity, occurs through a decentralized monitoring system. Farmers who are geographically proximate to each other tend to indirectly monitor the actions of their neighbors (see Trawick 2001). In the Taos Valley this process is referred to as “walking the ditch,” whereby a farmer who is not receiving water during his or her turn in the rotation will walk upstream along the main irrigation ditch to see who is taking it out of turn and preventing it from reaching his or her headgate. This decentralized monitoring is enabled by the fact that acequia farmers have traditionally lived on the private parcels of land that they irrigate, which are spatially clustered (A4a). These parcels all cluster near the river or a main canal, and are contiguous within an acequia. This contiguity and proximity, when combined with a rotational water distribution system (GS5b), facilitates low-cost, decentralized monitoring within each acequia (GS8a). This, in turn, helps enable sanctions, which are proportional to the severity of the offense, or graduated (GS8b). This monitoring system occurs within the first-level appropriation action situation (Fig. 5).
The modularity of the overall network accomplishes several things. Primarily, it represents a decomposition of the larger irrigation system into subgroups, with more frequent interactions within than between subgroups. Each acequia as a subgroup, or module, faces a set of collective action problems imposed by the biophysical relationships between their members. However, each group can resolve these collective action problems independently of other groups. This decreases the number of individuals (A1) involved in resolving any particular collective action problem. It is well established in CPR theory that smaller groups are better able to resolve collective-action problems due to the decrease in transaction costs involved (Ostrom et al.1994). While the transaction costs of monitoring and enforcement for the entire system may not be decreased in absolute terms by a modular community structure, in a system that is modular the costs of monitoring and enforcement are divided up amongst each of the modules, each of which can more easily monitor and enforce its own set of internal agreements.
A Multilevel Network Structure
A primary advantage of such a hierarchical network in a social system is that it can lower the number of individuals involved in resolving collective-action problems at each level. As noted above, the modularity divides the network up into smaller groups, each of which is able to deal with its own internal collective action problems more easily. The next critical step is at the second level, when the hubs of the network (mayordomos and commissioners) serve as representatives of their individual modules in resolving collective-action problems among modules. Because it is primarily the hubs that are involved in this second level, the size of the group remains small, even though many members are being represented. This small group size facilitates the resolution of collective-action problems that relate to a much larger geographic scale.
Relating Acequia Governance to the Biophysical System
The significance of the colors in the figure is to demonstrate the geographic extent that is covered by a particular governance regime, which consists of property rights and management regimes (McCay 1996). Property rights specify the unit of ownership and can be open-access, private, or common. Management regimes largely refer to the actual type of actor or organizational structure (communal, state, market-based, international) that manages a resource.
We begin here at level 0 because this is in fact a level of activity below the first governance level identified in Fig. 7. At level 0, parcels of land and headgates are owned privately, and each of these parcels is shown in a separate color. The management regime here is mostly private, as each farmer can decide what to do with his or her own land, and the water that is on this land. There are some communal management aspects even at this level since there are strong community pressures, and in some cases communal rules, regarding the use of these resources and specifically whether or not they can be sold out of the community. At level 1, common property holds over the main canals, the water they contain, and the land immediately surrounding them. Each color here corresponds to an acequia. The management regime here is communal, and there are strong constraints as to what each actor can or must do with respect the resource systems and resource unit. At level 2, inter-acequia interactions are mostly governed by the repartimientos. These are used to govern the main headgates off the rivers that are shared by acequias, and the water conveyed through these headgates. The property regime remains communal, although the enforcement of rules is somewhat looser in general, most likely because of the lack of an authoritative mayordomo-type actor at this level. One interview respondent compared this level of governance to “international relations.” The management regime is thus labeled inter-communal to distinguish it from the communal management at the first two levels. To summarize, the acequias use a mix of private and common property arrangements (GS4b) as well as private and communal management regimes C) across the geographic levels, with more lax institutional arrangements at the inter-acequia level.
Unpacking Action Situations
There are two types of relationships shown among the factors that contribute to collective-action. In one, two or more factors combine to produce a third. In the second, one factor directly produces another factor that itself is causally important for the outcome. This type of relationship indicates just how one variable affects a final outcome by affecting an intermediary variable. These two relationships can be combined.
It is important to emphasize that the factors included in the diagrams should not be understood as a recipe for successful long-term collective action. They are merely a summary of the main factors that seem to have helped acequia communities in the Taos Valley resolve their collective-action problems. Even with this level of representation, diagrammatic representations necessarily lose some of the nuance and complexity of thick social situations. As such, they should not be interpreted as a set of directions for sustained collective action in similar contexts, as these nuances are not captured and thus cannot be accounted for if we try to generalize these findings.
Appropriation Action Situations Within Acequias
The first-level appropriation situation within the acequias is shown in Fig. 8. The acequias have a heterogeneous distribution of property rights (GS4a) that creates leadership roles for acequia officers (A5). The officers’ property rights enable them to produce several important public goods that help maintain collective-action in the acequias. These include water distribution, monitoring (GS8a), sanctioning (GS8b), and conflict resolution (GS9). Additionally, the mayordomos’ rotational method of distribution (GS5b), when combined with the geographic clustering of user locations (A4a), enables a decentralized monitoring system within each acequia (GS8a).
The transaction costs involved in these activities are moderated by the modularity of the governance structure (GS3b), which decreases the number of participants (A1) involved in any single collective-action problem. Additionally, the proportional water allocation system (GS5a) produces a sense of equality within the acequias, despite their heterogeneous distribution of property rights. While not increasing an extrinsic benefit, this does increase subjective benefits for individuals with internalized norms of equity (Ostrom 2005:146), which the acequia farmers have shown to have through interviews (A6b).
A final important social feature is a high level of resource dependence (A8). Historically there had not been many alternative sources of livelihood in the valley, and with low levels of mobility, the acequia farmers have few options but to participate in the acequia governance arrangements. This aids cooperation because it creates very high costs of exit (A10), where farmers cannot afford to not participate in the acequia governance arrangements. This increases the costs of not cooperating, and avoiding this cost can be considered as a benefit of cooperation.
Several biophysical features are important as well. First, the desagues (RSI4b) ameliorate upstream-downstream conflicts by supplementing surface-water flows downstream of the acequias that have them, and averting waterlogged soils. Second, the acequia farmers employ a relatively low level of technology (A9) to produce and maintain unlined earthen ditches (RSI4a) that allow water to percolate into the ground. The use of earthen ditches to convey water combines with a strong surface-groundwater connection (RSL10) to yield an important storage capacity of the groundwater system (RSG8). This greatly increases the benefits of cooperation, particularly during droughts when surface water is scarce.
Provision Action Situations Within Acequias
While the appropriation of water in the acequias involves many individual decisions, provision activities primarily occur within a large group, when the members of an acequia gather for la limpia de la acequia (Fig. 9). Many of the variables that affect the provision situation by increasing the net benefits of provision carry over from the appropriation situation, as do their effects on collective-action. Some of the variables do not carry over. The system of decentralized monitoring discussed earlier, for example, is not used to enforce contributions to ditch cleanings. The majority of this monitoring and enforcement is done by the mayordomo with the support of the commissioners. The only new component of this action situation is the “appropriation” component. As mentioned before, this is the source of the benefits that are ultimately obtained through appropriation activities.
Appropriation Action Situations Between Acequias
The inter-acequia appropriation action situation consists of both the decisions made by the mayordomos to divert a particular amount of water into the main ditch of their acequia, determining how much water their members will have available to divert in the first-level appropriation situations, and the meetings the officers of several acequias hold to affirm, or consider alterations in, the legitimacy of these activities (Fig. 10).
While most of the important variables at this second level carry over from the first level, there are two important features here. As a result of the presence of the mayordomos and commissioners, the acequia networks are centralized (GS3a). They are also modular (GS3b), and the combination creates a hierarchical structure (GS3c) with two levels, one within acequias and one between them. Like other hierarchical networks, the acequias link modules with their hubs (highly connected nodes). This feature maintains low numbers of participants (only hubs/officers) involved in resolving collective-action problems at the second governance level between acequias. Network centrality plays an important role in decreasing group size at this level, while it does not at the first level.
The second important feature at the second level is a connection to external government organizations as the most important entities (GS1a) in resolving inter-acequia conflicts. Throughout the historical periods mentioned earlier, the external government, primarily in the form of local courts, played a crucial role in land settlement and arbitrating disputes (GS9) amongst waves of settlers.
The picture that emerges from a review of these action situations shows that many things are needed in order to sustain complex SESs over time. Moreover, it is important to understand the relationships among the contributing factors. This complexity and interconnectedness would argue against the highly simplified approaches to environmental and development policy analysis that have persisted in scholarship and practice (Ostrom 2007). I conclude by discussing the following: (1) the theories confirmed by this study (2) the methodological contributions this paper has made, (3) the implications of the conduct of a case study-based analysis, and (4) the use of the SES framework and its potential for future work.
Attributes that have helped the acequias persist for several hundred years are consistent with existing CPR management theory and the variables that have been shown to positively affect collective action, specifically, multiple levels of governance, small group size, proportionality of costs and benefits, low-cost monitoring and sanctioning mechanisms, and high resource dependence (Agrawal 2001, 2003). In addition to confirming several important theories, this analysis has shown how the concepts of social networks and multilevel governance can be combined to understand how a social system can map onto the biophysical system with which it interacts. Multilevel governance is understood both as a set of interconnected action situations, as well as a social network structure, and these perspectives are demonstrated to be complementary.
Several points should also be made with respect to the nature of this analysis as a case study. Because the data gathered from multiple units of observation largely confirmed each other, I do not view this study as vulnerable to the threat of internal validity to which single case studies are supposedly prone (King et al.1994). However, it is vulnerable to another problem that case studies face: a potential lack of external validity, or generalizability. While making generalizations to other systems that are highly similar (e.g., Coward 1977) is reasonable, the exact way in which the variables interact in the Taos acequia communities likely cannot be widely generalized.
Related to this, I believe that the analysis of the interactions of separate concepts and variables demonstrates an important point that is often emphasized in social-ecological research: that the causal significance of a particular concept or variable is frequently not meaningfully captured by its “independent” effects on an outcome. For example, the importance of centrality and modularity in the acequia case is to produce multiple levels of governance, a role that would not be captured if we were asking what percentage of an outcome they could explain as independent variables in a statistical model. This is not to say that such statistical models do not have their place, but that they should be more frequently complemented by analyses that diagnostically dig into such interactions.
The research presented here has also demonstrated the utility of the SES framework, particularly when complemented with the analytical device of a structured set of action situations, as a critical aid on guiding a single case analysis. Much of the inspiration for the methodological diagnostic steps outlined earlier comes from the SES framework and its progenitor, the IAD framework. This analysis has taken advantage of an element in both of these frameworks—a set of interconnected action situations—that previously had been underutilized in their applications.
Ultimately, however, we need not just case studies of particular SESs, as this one is, but comparative in-depth studies. I believe that enabling such comparative work, along with facilitating diagnostic processes such as the one conducted here, is the primary purpose of the SES framework. To facilitate this, studies must measure a common set of variables with the same protocols. While the SES framework has proved useful in providing the potentially relevant variables, it was not as helpful in establishing a protocol for their measurement. From a comparative perspective, the somewhat ad hoc, or site-specific, nature of variable operationalization is probably the biggest weakness of this analysis. Standardized measurement of variables is mostly missing across research projects in CPR management, and it is currently missing from the framework. Therefore, I would advocate further improvement and formalization of the framework, particularly through the establishment of standards for variable measurement. This would help facilitate more synthetic findings across a diversity of SESs.
In conclusion: using these methods, I have found that the acequias have survived in a high desert environment with a set of nested institutional arrangements that form multiple levels of governance, with each level corresponding to a larger geographic scale of the irrigation system. These multilevel governance arrangements are constructed by networks of farmers that interact in social arenas organized around well-identified governance tasks. Additionally, across and within each of these governance levels, social and biophysical features interact to sustain the cooperation needed to maintain the irrigation system and crop production over time.