Socio-demographic characteristics of the interviewees

The average age of the interviewees was 52.82 years, with a minimum age of 18 years and a maximum of 86; of those, 85.3 % were male and 14.7 % were female, with an average schooling of 4.96 years. In addition, 80.0 % practice agriculture and livestock breeding as their primary activity and 20 % practice tertiary sector activities. These characteristics are common for rural producers in México. ^{Ávila et al. (2011)}, for example, report that the age of rural producers of northern México is 53.4 years old and they have an average schooling of 6.5 years. For the present study, the advanced age and low formal education of the interviewees are relevant because they signify a long-term coexistence with the river; also, their perception of the problem of river pollution derives in large part from this experience, not from information transmitted by formal education.

Relationship between local residents and the Tlapaneco River

Of those interviewed, 72.6 % currently use water from the Tlapaneco River; of these, 96.2 % are users from before 2001. The water use has changed since 1990, due to pollution of the river; 95.8 % would use the water for washing, bathing, and recreation activities. Currently, 69.5 % use it for agricultural activity, 5.26 % for washing, bathing, or amusement, and 1.05 % for livestock activities. The generalized use of water from rivers in México for activities relating to cleaning and hygiene, as well as for watering livestock, is a practice that has been inherited from the conquistadors of México, a practice still present today in the rural communities of México like the ones by the Tlapaneco River and certain regions of Spain, and whose historical vestiges have been documented in Spain in the Municipal Ordinances (^{Rodríguez, 1998}). Of those that are not users today, 83.5 % stopped using the water before 1990 due to river contamination. The reasons why they stopped using the river water are: they do not cultivate (2.22 %), they use another water source (10.53 %), or because it is polluted (11.58 %).

Perception of the quality of water of the Talpaneco River

The riverside population perceives that the Tlapaneco River water quality has deteriorated. Of those interviewed, 84.2 % agreed that the water was clearer in the past; 10.5 % strongly agree; 35.8 % consider that currently the water exhibits changes in appearance (foamy, greasy, ashy, dirty, cloudy, ugly, or brown); 26.3 % consider that its color has changed (black, brown, greenish, greyish, yellowish, not clear, or dark); and 23.2 % consider that it suffers from contamination processes (discharges of drainage, hospital and chemical waste). The evaluation of the river’s condition reflects the predominance of visual indicators for landscape (^{Hu and Keeley, 2014}), particularly the clarity of the water. In general, the perception predominates that the water quality ranges from regular to bad (Table 1). Interestingly, the people who recently began to utilize the river water coincide in that its quality is regular or very bad. In general, the water is used even when there is awareness that it is not good.

Table 1 Use of the Tlapaneco River water and perception of its quality. 

1=Used the water previously and still uses it; 2=Used the water previously and stopped using it; 3=Did not use water previously and uses it presently; 4=Never has used the water.

The Kruskal-Wallis test indicated that the amount of irrigation surface was a variable that had an effect on the general perception of the water quality (Table 2). The Mann-Whitney test used for comparing the groups indicated that whoever has more than one hectare differ in opinion from those who have less than one hectare of irrigation land and that their perception is more pessimistic. Of the group with more than one hectare, 92 %considers that the water is bad or very bad, while for the group with 0.0 to 0.25 ha and 0.26 to 1.0 ha, the percentage is 86.7 % and 89.5 %, respectively. This variable also influenced the opinion about the water quality for vegetable cultivation; 100 % of those who have more than one hectare of irrigation lands held the opinion that the river water is not adequate for vegetable cultivation, an opinion shared by 93.1 % who own 0.0 to 0.25 ha and 97.4 % who own 0.26 to 1.0 ha. In these last groups there were interviewees that thought that the river water is good or very good for farming vegetables.

Table 2 Kruskal-Wallis test for evaluation of differences in perception of pollution of the Tlapaneco River between age, education, and irrigation surface area groups (value of p). 

Age groups (years): 18 - 40, 41 - 60, more than 60; Education (years): 0 - 3, 4 - 6, more than 6; Irrigation surface area (ha): 0.0 - 0.25, 0.26 - 1.0, more than 1.0.

Opinions on the change in river water quality that has taken place over time were influenced by the level of schooling (Table 2); 100 % of those who had less years of formal education (0 to 3 years) thought that the river water was clearer in the past than now, while in the stratum of those who have four to six years of schooling, there were opinions where they did not know if that was true (3.8 %) or that they disagreed with the statement (3.8 %). Among those who received more than six years of formal education, there was a similar tendency, where 4.3 % said they didn’t know and 8.7 % were in disagreement (Table 2).

The variable economic activity (differentiated between activities of the primary sector and those of the secondary and tertiary sectors) influenced opinions about the quality of river water for the cultivation of vegetables (Table 3). While 100 % of those interviewed whose activity was not agriculture and livestock production considered that the quality varied from not very good to very bad, 3.9 % of those who have agriculture or livestock as their primary economic activity considered that the water good for vegetable farming. We consider that this difference can be explained by the fact that some agriculture and livestock producers continue to cultivate vegetables on Tlapaneco riverside lands and their opinion somehow attempts to avoid the spread of a negative opinion on the quality of their products.

Table 3 Mann-Whitney test for evaluation of differences in perception of pollution of the Tlapaneco River between economic activity, informant type, and gender groups (value of p). 

Economic activity: primary sector, secondary or tertiary sector; Type of informant: key informant, non-key informant; Gender: masculine, femenine.

The type of informant influenced the opinions over changes in water quality (Table 3). Of key informants (older people or who have some position of responsibility in the community), 100 % had the opinion that the river water was clearer in the past. By contrast, 3.4 % of those who were not considered key informants said they did not know if this was true, and 5.2 % of them had the opinion that they did not agree with the statement that the river water was clearer in the past. We consider that this difference could be correlated with the less frequent contact that they have had with the river’s ecosystem and because they have less knowledge than the key informants. For the development of restoration policies, strategies and programs, the selection of local participants will be influenced by these differences in knowledge and perception about the river, which generates different visions and conceptualizations. Their selection will depend more on the objectives to be reached, and this will require building different participation models (^{Antunes et al., 2009}).

Perception of the origin of pollution in the Tlapaneco River

Of the interviewees, 82.1 % had the opinion that the population in general is responsible for polluting the Tlapaneco River water; 56.8 % consider that the city of Tlapa, the center with highest demographic concentration of the river basin, is the primary cause; 35.8 % believe that the pollution originates in the high part of the basin, encompassing Copanatoyac to Tlaquiltzinapa. Only 7.37 % mentioned that it originates in the low zone of the basin, from Atlamajac to Huamuxtitlán.

The primary source of contamination identified was the discharge of residual waters (65.3 % of interviewees); 25.3 % considered that the contamination is caused by solid waste (garbage); 4.2 % by waste from clinics, mechanical workshops, and car washes; and 5.2 % by the increase in population, lack of treatment of sewage water, and lack of awareness in the population. The fact that the discharge of wastewater is perceived as the primary cause of pollution by the majority of those interviewed agrees with what was reported by ^{Crona et al. (2009)}, who mention that the communities located near wastewater dumping sites are the ones who perceive the problem of pollution more. In contrast, the population in densely populated urban centers, in addition to wastewater dumping, assigns great importance to factors like the generation and disposal of solid residues (^{Arellano et al., 2009}).

Perception of the effects of pollution of the Tlapaneco River

The population of the basin perceives that the pollution affects them directly. After interviewing them, 98.9 % answered affirmatively that it affects them and their family; 55.8 % considered that it deteriorates their health; 15.8 % obtained a reduced harvest; 9.5 % said that the water can only be used for watering certain crops; 8.4 % mention that it contaminates food and they cannot fish; and 5.3 % say that it causes a bad odor and harms the environment. All of them (100 %) manifested that the water pollution affects other people in their community, mainly their health (56.8 %), the irrigation of certain crops and their production (30.5 %), and because it contaminates sources of drinking water and agricultural products (10.5 %). 27.4 % mentioned that they stopped cultivating watermelon, melon, green chile, or tomatoes; 27.4 % stopped using the water for drinking, washing, or bathing; 17.9 % stopped planting crops that are not vegetables; 12.6 % stopped fishing; and 10.5 % stopped frequenting the river or using it in general. 93.7 % consider that they have had some economic loss because of the polluted water from the Tlapaneco River; 47.4 % had a lower income, 42.1 % acquired substitute products (pipe or bottled water and fishes), and only 4.2 % suffered a total loss at some occasion.

Those interviewed are aware of the consequences of the river pollution on their agricultural and recreational activities. All the interviewees consider that the river water is not clean and that it is of bad quality for cultivating vegetables because it sickens plants and contaminates the harvest, which cannot be sold. In addition, 74.7 % consider that it is not good for bathing. This perception is because they think that bathing in the river will provoke allergies (irritation, welts, itchiness) or pimples on the skin. The consensus regarding the river water’s low quality for agricultural production is notable, and can be explained because riverside agriculture depends on irrigation with river water. The fact that the residents pay more attention to the effects on crops coincides with studies that have shown that users perceive more clearly the effects on production than on the environment (^{Barnes et al., 2009}). The interviewees seemed worried because the produce could not be sold, and not because of the effects on the health of the population that consumes the agricultural products, which coincides with the attitude of rural producers from other regions (^{Carr et al., 2011}). The perceived effects on the health of those who use the river water is related to the individual’s prior experience, as reported by ^{Fleisher and Kay (2006)}, who found that bathers that frequently use the water reported as polluted have a greater perception bias concerning the risk of contracting skin diseases from bathing in these waters, compared to non-bathers.

Even though the riverside population pays greater attention to the effects of river pollution on agricultural production, they also perceive the ecological effects of contamination; 81.1 % manifested being in agreement that there were more fish in the river in the past, and 18.9 % strongly agreed. They consider that people would fish in the river before and now they do not, and that fish have decreased due to the presence of contaminants in the river water (grease, chlorine, oils, and pesticides). They also consider that there were more birds in the in the river and along its banks (86.3 % agreed and 7.4 % strongly agreed). They associate this with there being more food in the past because the water was less contaminated. The understanding that the residents have of the problem of river pollution, its causes, and its consequences, is important so they can assume responsibility in the restoration and conservation of the river, as well as in the induction of conservationist behavior (^{Larson et al., 2009}).

Perceived solutions to water pollution

Of those interviewed, 61 % consider that the pollution of the Tlapaneco River has a solution, while for 39 % it is an irreversible process. Although the majority of the interviewees are older than 50 years of age, they have a positive opinion about the rehabilitation of the river, in contrast to residents of riverside towns from other areas and of similar age who express pessimistic opinions on the subject (^{Braun and Shoeb, 2011}). Concerning who is responsible for restoring the river water’s quality, 34.7 % of interviewees answered that it is the population, the three levels of government (municipal, state, and federal), and institutions; 28.4 % believe that it is the responsibility of the municipal president and offices, with the support of legislators, while 20 % think that it should be the municipality of Tlapa and other municipalities that cause most pollution, with support from dependencies.

Regarding perceptions of the solution to the pollution of water, and coinciding with what was stated by Balkman et al. (2002), 16.8 % of interviewees consider that the solution is in the construction of municipal wastewater treatment plants, and 10.5 % consider other treatment options, such as filtration ditches. Raising awareness in people is also considered important, in the sense of not throwing garbage into the river and retrieving the garbage already there, an opinion expressed by 23.2 % of those interviewed. 12.6 % believe that the solution lies in organizing the population (including orientation groups for assemblies and gatherings). The interviewees are aware that the decontamination of the Tlapaneco River is expensive or very expensive, primarily because it is a long river, an opinion shared by 72.6 %. 9.5 % consider cleanup of the river economically feasible only if there is organized participation from local residents.

The population is skeptical about the role that authorities have in solving the problem. 55.8 % of interviewees believe that the authorities only make promises; 12.6 % attribute this failure to deliver to the authorities’ lack of financial resources; 10.5 % believe they would deliver if the town applied more pressure; and 7.4 % believe that authorities do not assume responsibility for sanitation of the river, even though it is their duty because it is harmful to the town. Trust in institutions and authorities is important for any river sanitation initiative and, although in this case it is low, it is possible to involve the population since the majority is aware of the problem; as ^{Jorgensen et al. (2006)} report, the lack of trust in institutions is not always associated with negative environmental attitudes and with a low willingness to pay for improving the quality of the polluted waters. It is necessary for government institutions to rebuild their social capital with the communities, and one medium is through dialogue with them, as in ecological restoration projects where the population expects to be an active part of the process or, at least, to be consulted (^{Tunstaff et al., 2000}).

Perceived future benefits of river sanitation

The interviewees perceive future positive and beneficial effects from cleaning up the Tlapaneco River; 63.2 % consider it important or very important that their children and grandchildren enjoy a river with clean water for agricultural, domestic, and recreational use, while 30.8 % consider that diseases and conflicts between water users would be avoided. The fact that the riverside population worries about the resource’s quality for future generations is important, and this worry is associated with an expected benefit as a result of its use. This is important to consider in the design of any environmental awareness and river cleanup program, as there is evidence that people are more willing to participate when they perceive benefits for the individual or the community than when they perceive risks or real damages (^{Hartley, 2006}). This also complements the idea that environmental decisions are part of a long term process in which people evaluate the future benefits and costs, not just the present ones (^{Hendricks and Nicolaij, 2004}).