*3.2. Nestedness*

Four municipal seats reported cross-level interactions with stakeholders from the two highest jurisdictional levels of the state (except Santiago Tepetlapa) and nation. Conversely, among eight municipal agencies in which the municipal agen<sup>t</sup> or water committee was responsible for the water supply system for domestic use, San Antonio Abad, Santa Cruz Corunda, and El Enebro did not report interactions with any stakeholder at higher jurisdictional levels (i.e., the state level), nor did San Antonio Abad with stakeholders at the national level (Figure 5b). Reports of interactions between San Antonio Abad, San Miguel Aztatla, and Santiago Quiotepec with their municipalities (e.g., Santiago Ihuitlan Plumas, Concepción Buenavista, and San Juan Bautista Cuicatlan, respectively) were low (21–40%). A similar situation was present in the interactions reported between La Mexicana and Santa Cruz Corunda with stakeholders at the national jurisdictional level (21–40%), such as CONAGUA. The four municipal seats mainly presented interactions with the national jurisdictional level, which was recognized through interviews (81–100%, Figure 5a). In the ten activities analyzed, it should be noted that the 13 communities in this study reported

interactions with the assembly of water users with regard to decision making. Likewise, the commissariat of communal and ejidal assets (agrarian council) as well as migrant users, either individually or in an organized manner (directive), were reported as stakeholders involved in the first order of governance of the water supply system for domestic use in all communities (Table 3).

**Figure 4.** The multi-level structure of the governance of the water supply system for domestic use in Mexico. The squares and circles refer to the laws (institutions) and stakeholders (circles), respectively. Arrow thickness only serves to differentiate among arrows when they intersect. LGEEPA: Ley General del Equilibrio Ecologico y la Protección al Ambiente. SEMARNAT: Secretaria del Medio Ambiente y Recursos Naturales. Adapted from: Gumeta-Gómez et al. [60].

**Figure 5.** (**a**) Percentage of interviewees from each community who mentioned some interaction with the different stakeholders belonging to higher jurisdictional levels. Communities marked with an asterisk (\*) are municipal seats that cannot be nested within themselves, so interactions at the municipal level were not considered. (**b**) Interaction scheme of the 13 communities studied with other actors at higher jurisdictional levels: municipal (square), state (triangle), and national (diamond). The communities where a municipal agen<sup>t</sup> or a water committee administers the water supply system for domestic use are shown in a circle and the municipalities in squares. Abbreviation definitions can be found in (**a**).

**Table 3.** Interactions between actors at the local level within the 13 studied communities. The commissariat of communal or ejidal assets corresponds to those responsible for the ejido agrarian territory or agrarian community with collective land tenure. \* Stakeholder responsible for the operation of the water supply system for domestic use in the community.


We did not observe significant nestedness in the results of the NeD analysis (Z = 0.538, *p* > 0.05) in any of the null models for the communities in which water committees were present or in which the municipal agen<sup>t</sup> was responsible for the water supply system for domestic use (Table 4). However, in communities that are municipal seats, we obtained a significant nestedness value of 66.66 (*p* > 0.001) with the state and national levels. This result was consistent in all the null models (EE, CE, FE, FF, and EF). In all analyses of both community matrices, we used 50 random null matrices when calculating the Z value.

All municipal seats present cross-level interactions at the national level and to a lesser extent at the state level, which could explain the significant nestedness found with the NODF metric. In the case of the municipal agencies, half of them did not report crosslevel interactions or only reported cross-level interactions with a single level (e.g., state or national), which could explain the non-nestedness of the group. However, we may consider that Santiago Quiotepec, La Mexicana, San Francisco Teopan, and Santa Cruz Capulalpam are nested or at least show a degree of nestedness, as they present cross-level interactions with the state and national jurisdictional levels.

**Table 4.** Nestedness results obtained with the Nestedness based on Overlap and Decreasing Fill (NODF) algorithm in the Nestedness for Dummies (NeD) online software for two groups: (1) communities in which water committees and municipal agents are responsible for supplying the water for domestic use and (2) municipal seats in which the municipality is responsible.


1 Communities with a water committee or municipal agent: Enebro, San Miguel Aztatla, Santa Cruz Corunda, San Antonio Abad, Santa Cruz Capulalpam, Santiago Quiotepec, La Mexicana, and San Francisco Teopan. 2 Municipalities: Santa Magdalena Jicotlan, Concepción Buena Vista, Santiago Ihiutlan Plumas, San Juan de Los Cues, and Santiago Tepetlapa. 3 *p* > 0.05. 4 *p* > 0.001. NODF\_FILL: Nestedness of the fill. NODF COL: Nestedness of the column. NA: Not applicable.
