Citizen science is defined as collaborative science between citizens and professional scientists, in order to investigate a topic that is relevant to the local community (Cohn, 2008; Buytaert et al., 2016; Vohland et al., 2021). It corresponds to the participation of amateur volunteers from local communities in scientific research (Paul et al., 2018). In this way, the interests of both the scientific and local community are aligned to achieve a common goal, such as the sustainability of a local resource (Perevochtchikova et al., 2016). There is a huge increase in acceptance globally in recent decades (Bonney et al., 2014). Therefore, citizen science may be a resource with a huge potential, mainly because it can fill knowledge gaps in the territory, can increase environmental awareness to provoke a behavioral change, facilitate traditional monitoring incorporating cost-effective alternative help, and can provide incentive corporate funding and support (Haklay, 2013). Currently, various citizen science programs, where non-scientists participate in the design, collection, or interpretation of data, have been successfully implemented in several fields of study, such as ecology, ornithology, and astronomy (Buytaert et al., 2014; Shupe, 2017). Examples include websites iNaturalist, eBird, ZooUniverse, and CitSci among others. This enables the exploration of scientific questions about greater scales and includes locations without available data (Loss et al., 2015; Reed et al., 2018; Kirchhoff et al., 2021). However, in certain disciplines such as geology, hydrology, and environmental chemistry, there has been a more gradual integration of citizen science, mainly because the technical experience is needed for effective sampling. This requires participant training within a research project. It has been shown that through these collaborations, academics are able to increase the scope of their research and obtain better information on spatial and temporal variability (Weyhenmeyer et al., 2017). Over this decade, bottom-up approaches have been conducted in implementing community-based water quality monitoring in response to local concerns regarding environmental issues (Bonney et al., 2014; Alender, 2016; Jollymore et al., 2017; Enqvist et al., 2020; Hegarty et al., 2021). Different ways to perform citizen science participation such as community-based water quality monitoring is possible through contributive, collaborative, and co-creative initiatives (Bonney et al., 2009). Table 1 summarizes different community-based water quality monitoring initiatives over the past decade carried out using the citizen science methodology, mainly in Mexico, Colombia, the United States, and European countries such as the Netherlands, the United Kingdom, and France. These studies involve interested volunteers to be trained in the monitoring of basic water quality parameters, data collection, and interpretation of the data. Training the volunteers develops their capacity to carry out independent monitoring and assigns the implementation of these tools to volunteers in rural areas, where water quality is generally difficult to monitor for non-specialized people (Baalbaki et al., 2019). However, the benefits of these citizen science trainings include changes in attitude, behavior, and increased awareness about relevant issues within a community (Roetman and Daniels, 2011). Therefore, ensuring that the data obtained is valuable and reliable remains a challenge that requires the dedication of both the scientist and the scientific volunteers. In Chile, there is still a relatively low citizen participation in subjects related to hydrology and environmental chemistry topics, although projects such as “citizen pluviometers” have been developed, that encouraged the installation of rain gauges at home for sampling and uploading data onto an internet platform (DGA, 2004). Furthermore, community-based water quality monitoring has been applied to investigate the accelerated increase in nutrients in Lake Panguipulli, in southern Chile (Amsteins, 2013). Community-based water quality monitoring initiatives have also been implemented in rural coastal communities of Central Chile to investigate water quality and availability (Rivas et al., 2020), but still there are specific initiatives that are scarce, relative to other areas in the world (Sherbinin et al., 2021). However, the majority of research projects stem from contributive proposals from academia, rather than collaborative and co-creative from local initiatives. Overcoming this hurdle, so that the community takes a lead in these initiatives, could transform the interactions between communities and their local environment, and help fulfill the United Nations (UN) Sustainable Development Goals (SDGs). In this way, citizen science projects highlight the importance of good water stewardship within an ecosystem, facilitating harmonization and shared areas of interest between communities and researchers. There are opportunities in Central Chile to develop community-based water quality monitoring over various rural locations, exposed to different land uses, involving citizens that are keen to understand and attend issues around the water quality problems. Particular consideration is given to the coexistence of various land uses such as industrial activities, irrigation and agriculture, and urban and rural populations. On the other hand, an increase over the past two decades in forest plantations of non-native tree species such as pine and eucalyptus is likely to continue. These issues, together with a prolonged water shortage (Garreaud et al., 2018; Boisier et al., 2018), are accentuated in rural communities without drinking water (Aldunce et al., 2017). At present, the Boca Itata area, located in the coastal area of the Ñuble region of Central Chile, is home to rural communities dedicated to subsistence farming and they make up a rural area with lack of drinking water. Groundwater is important for both irrigation and consumption. In this area, the lack of drinking water prevents the development of water conservation strategies, as communities receive weekly provisions of drinking water from water supply trucks (Municipality of Trehuaco, 2018). Furthermore, wells are located near subsistence farming areas, it is likely those agrochemicals such as nitrate and phosphate, enter the surrounding water sources. Therefore, community-based water quality monitoring can help to identify the chemistry of the water sources based on the lithology of the study place and look for potential solutions if they know what type of water is present. Moreover, systematically generated data from citizens can lead to more thorough analysis and the application of hydrogeochemical modeling that allows prediction of water composition and the resulting mass transfers.

To estimate water composition and weathering reactions to know water quality, inverse modeling can be used as an important tool (Plummer, 1992). Inverse modeling efforts to account for the chemical changes that strike as water evolves along a flow path (Plummer et al., 1994). Inverse mass balance modeling efforts to assessing sets of mole transfers of phases that account for changes in water chemistry between one or a mixture of initial water compositions and final water compositions (Parkhurst and Appelo, 1999a). In this way, it is possible to determine the reactions that lead to the conversion of minerals and explain the changes in water chemistry (Parkhurst and Appelo, 1999b; Parkhurst and Appelo, 2013). By using the lithology of a place and knowing the solutes present in the water through the PHREEQC model, it is possible to understand and characterize historical community-based water quality monitoring data and evaluate the geochemical processes that generated water quality changes. PHREEQC has been widely used for hydrogeochemical analysis of groundwater (Naderi Peikan and Jalali, 2016; Mahaqi et al., 2018; Abdelshafy et al., 2019). Naderi Peikan and Jalali (2016) explained how the water chemistry changed along the flow path. Li et al. (2010) carried out the analysis of the hydrochemical evolution of groundwater and the mechanisms of its formation, identifying variation in terms of its composition passing from the Ca–HCO₃ ⁻ and Mg–Cl type to the Mg–Cl–HCO₃ ⁻ type.

Consequently, this study was focused on the concern of the community to know their water quality composition and to find a topic that ensures future drinking water. Therefore, the objective of this co-creative study was to evaluate the water quality (pH, total iron (Fe_T), alkalinity as HCO₃ ⁻, hardness (Ca²⁺ and Mg²⁺), temperature, sulfate (SO₄ ²⁻) chloride (Cl⁻), and nitrate (NO₃ ⁻) and hydrogeochemical processes through the community-based water quality monitoring and geochemical modeling. This study was carried out in the rural area of the Itata Valley, Boca Itata in the Ñuble Region of Central Chile.

In order to carry out this, together with the community, basic information was generated which was used in a geochemical model (PHREEQC) to understand the changes in chemical quality and the origin of these changes. In this way, to initiate the formation of a network within the community that promotes issues around water security.

This study considers community-based water monitoring to highlight how data collection using simple field sampling techniques can be used in geochemical modeling to promote rural water management. This citizen science study supports the notion that volunteer involvement in the project can foster community motivation and self-identification, raise awareness of the importance of clean water, and certainly reduce uncertainty about water issues in the community (Jordan et al., 2015; Gray et al., 2017). In this way, a direct link can be formed between the benefits provided by continuous measurements of water quality by the community of people and the concern of the local government to cover the environmental points that it cannot measure regularly. The monitoring of water quality with different parameters carried out by the community can become a regular practice to obtain an early warning system of solute levels and control the measured parameters for future rural drinking water system installation for the community. In this study, it was identified that one point was systematically of better quality and served to identify it as a potential point to suggest to the local government the installation of rural drinking water. Hence, they become significant actions for the conservation of the water quality of their territory.

Considering the current scenario of lower water availability, it is also highly necessary to evaluate the quality of the available water for human consumption. A decade ago, there was a greater availability of surface water (Garreaud et al., 2018), and groundwater availability was less of an issue. However, there is now an ongoing situation related to a lack of groundwater in Central Chile, enhanced by the mega-drought present in the country (CR2, 2015). Rural areas, that are more directly dependent on groundwater, are most affected by water scarcity. Therefore, it is necessary to be focused on successful practices within rural communities, thus that they understand the problem of decreasing water availability and the resulting consequences on water quality. Through this study it was identified that an initiative that emerged from the community-based group and contributed positively to social–ecological fit, refers to the inability of the institutions to have a greater spatial coverage of water quality in rural communities to adequately align with water quality dynamics (Enqvist et al., 2020).

However, the results indicate an overall good physicochemical water quality, but with higher nitrate levels, that exceed (>90 mg/L), in most wells an exception of well 4, the maximum limits established in the World Health Organization (WHOS) standards with a maximum of 50 mg/L (Ward et al., 2018). This type of groundwater anomaly is not related to the lithology of the site. However, anthropogenic activities developed in the area such as agriculture, livestock, and the use of septic tanks produce levels of ammonium and nitrate that can remain available in the surrounding environment. In the absence of natural sources of nitrogen, the values of NO₃ ⁻ should not exceed 10 mg/L. The Chilean standard NCh1333 does not include nitrate, however, according to the Chilean Drinking Water Standard 409/1, nitrate–nitrogen should not exceed 10 mg/L, given its adverse health effects (Herrera-Apablaza, 2018). In the case of iron, it showed ranges between 0.23 and 2.2 mg/L, which is high for the Chilean standard of human consumption (NCH 409/1), especially in well 3. The increase in this parameter brings with it aesthetic problems in the water or problems in the water supply systems. However, water alkalinity was a good buffer, with values reaching 150 mg/L CaCO₃. Low alkalinity causes a greater sensitivity to contamination, which allowed to balance sudden changes in the pH of the water, thus allowing to avoiding fouling and acidification problems. Previous studies have indicated that borates, silicates, and phosphates may also contribute to alkalinity, and in this area (between the mid to deep part of the basin) there have been previous reports of high boron (0.75–1.10 mg/L) and silicate (3–10.5 mg/L) concentrations (CIREN, 2003; Yevenes et al., 2018).

Based on the Piper diagram, it was indicated that most samples present a type of water Ca (Mg)– HCO 3 −   although there are some samples with Na-Cl, as well as types of mixed water which varied in the different seasons of the year, but the dominant ions were Ca²⁺, Na⁺, Mg 2 + , and HCO 3 − (Figure 2). This secondarily contributes to the formation of bicarbonates and thus to the alkalinity present in the area [Appelo and Postma, 1993, cited by (Martínez and Osterrieth, 2013)]. Water hardness is reported due to the presence of Ca²⁺ and Mg²⁺ in the water, present in lower levels compared to alkalinity, which ranged between 50 and 100 mg/L (Tables 2, 3). Regarding seasonal variation, and based on the Piper Diagram, during winter and spring (wet) seasons, it has been determined that most of the water present in the study area is bicarbonated classified as calcium–magnesium bicarbonate and magnesium–calcium sodium. During the summer and autumn periods (dry season), most of the water is bicarbonated, and a group is classified as a mixture of water (Mg–Ca), calcium bicarbonated and/or chloride type (Figures 3A,B). In general, according to these results, waters are associated with young waters, with little circulation time and recharged directly from precipitation. Only during the dry season, chloride type can indicate more residence type of the water.

By analyzing the inverse modeling, the influence of technology in the water chemistry of Boca Itata is recorded, where the dissolution of carbonate minerals plays a fundamental role in the composition of the water, since minerals such as calcite, dolomite, gypsum, and halite were found in the trajectory in dissolved form, producing an increase in the concentration of higher ions. Other factors that influence the chemical composition of the water are the precipitation of compounds containing Fe²⁺, which intensifies the high levels of this ion. According to this analysis carried out with inverse modeling, together with the geochemistry of the area, it was determined that from all stations analyzed, the point W4 would present optimal general chemical conditions for the implementation of a rural drinking water system (RDWS), given the need of the community. This is the point where the composition of the water presents better chemical conditions and presents no great changes in the geology of the area and anthropogenic activity.

In this study, it is worth highlighting the importance of the rural community of Boca Itata, who, due to their concerns, sought and were part of the development of a citizen science project, such as community monitoring of water quality (Figure 4). In order to determine the quality of the water they use daily, an essential natural resource for people and that in many parts of our country there are still communities that do not have the necessary support to carry out these investigations, mainly due to budget limitations and scientific knowledge. This type of initiative is a contribution to the generation of knowledge and the participation of people, which brings with it, greater confidence and involvement with issues as important as water quality. This type of initiative can be implemented in a simple way through social organizations, neighborhood associations, or interested groups and can allow the creation of a surveillance system, where the participants themselves identify possible problems in the water and can alert the community to these cases, in order to be able to search for the origin of the problem and find solutions with the help of researchers, scientists, or state agencies in charge of these issues (Aravena et al., 1989; Aqualogy Medioambiente, 2013; Herrera and Custodio, 2014; Santibañez, 2016; Yevenes, 2016; Yevenes, 2018; Brintrup et al., 2019).

The results were disseminated through scientific conferences, regional newspapers, as well as face-to-face conversations, which are the baseline for future research on community participation. Similarly, effective communication with the local community was essential to obtain satisfactory results. The researchers were interested in building trust with the community through the sharing of the results, and discussing potential solutions to improve the current situation, such as those reported in other studies (Jordan et al., 2015; Perevochtchikova et al., 2016; Baalbaki et al., 2019). This initiative in Central Chile provides the opportunity to build relationships between academia and local communities, generating valuable information and diminishing the uncertainty about consumed water content for local communities, in addition to allowing the community to act as a self-identified community with this resource. This initiative has encouraged local citizens to get involved in data analysis, as well as considering potential corrective measures in order to prepare for the installation of rural drinking/potable water (RD/PW) in the local area. Local demand for water is increasing, considering both drinking water and monocultures from the forestry industry (Hurlbert et al., 2009). Furthermore, this increase in water use is further aggravated considering current climate change projections, which estimate a reduction in the basin flow of up to 50% over the next few decades in Chile (MME, 2017). This is in addition to an increase in the frequency, intensity, and duration of drought-related phenomena (Tarhule, 2017). These threats are enhanced by the absence of a well-defined and consistent water resource plan, along with disaggregated and poorly coordinated governmental sectors (Montaña et al., 2016; Urquiza et al., 2019). Furthermore, the community faces strategic difficulties to obtain rural drinking/potable water (RD/PW), considering its geographical location and future supervision. Potentially dangerous chemicals are more readily concentrated in groundwater compared to surface water, mainly due to the longer residence times for groundwater (Burri et al., 2019). The results indicated that the prevalence of septic tanks in the area, combined with the absence of sewage treatment, might cause groundwater contamination, as well as the proximity of the study area to the coast.

However, community-based efforts can provide important complementary research to water quality government sampling stations, and even raise public awareness of the water paradigm shift so that the rural population learns the responsible management of water to reduce pollution prior to consumption. The challenge is to apply adaptive solutions so that there is more frequent control of water quality in rural areas.

This study demonstrates that community organizations offer an alternative methodology to rural water stewardship through a citizen science approach. Moreover, key information from areas where the data are not available to study water quality. This experience gives an example of a pilot project for an early alert system of water quality built from the community and that could be replicated throughout neighboring communities, local and regional governments. This would create a type of the rural community water network, which is an appealing model to those responsible for regional water management. Among the seven physicochemical water quality parameters sampled, iron and nitrate in wells presented the greatest variation between the summer and winter seasons. Trained volunteers within the community were committed and available to participate in the study, despite having to also fulfill other activities in the rural area, mainly because the water quality for them is overly concerning.

Community results were supported with reliable, repeatable, and accurate data on water quality and chemical concentrations in the water. In this way, it was possible to identify variations in indicators of water pollution, and trained volunteers can notify these changes to relevant authorities. However, there were issues regarding the measurements of sensitive parameters in the field. Future studies should focus on resolving this issue. At this stage, it was not possible to measure the impact of the industry, as only basic parameters were considered in this first approach to community monitoring. Ultimately, the success of the study was mainly due to the mutual efforts made by the community and academia.