Sustainability Assessment and Sustainable Management Scenario of Lake Batur in Bali, Indonesia: Insights from a Multi-Aspect Approach

Abstract

Lake Batur is part of the Batur UNESCO Global Geopark and an active caldera of Mount Batur on Bali Island, Indonesia, and it has no inlet or outlet. The current state of the lake has deteriorated due to severe environmental degradation. The lake’s management will focus on the environment and other aspects planned in an integrated, sustainable lake management scenario. The research aims to develop a Key Performance Indicator instrument to determine the lake’s sustainable status. These indicators included environmental, socio-cultural, economic, institutional-management, and infrastructure-technology aspects. The method used is Multi-Aspect Sustainability Analysis to determine its sustainable status and identify the factors that have the most leverage in actions to restore Lake Batur. The primary data was collected through in-depth interviews, questionnaires, and field surveys. Respondents were stakeholders who knew the factual conditions of Lake Batur. The research results show that Lake Batur is in a state of alert or declining sustainability, even predicted to become critical if there is no significant management soon. The performance of all aspects is in the alert category (unsustainable or <50/100) except the social-cultural in the acceptable category (not yet ideal/sustainable). The management scenario of Lake Batur, at least increases to the acceptable category, includes controlling the number of floating net cages and the forest area, developing the potential of tourism and fisheries, reducing conflicts, establishing rules for lake use, increasing the role of the central government, and digitalization of lake management development, construction of water infrastructure and the use of renewable energy.

1. Introduction

Lakes provide numerous essential ecosystem services, including clean water supply, fisheries support, tourism promotion, agricultural assistance, biodiversity conservation, water cycle regulation, hydroelectric power generation, and cultural and religious functions. They also serve as critical food sources for human populations [1,2,3]. A lake is defined as a body of water situated on land that occupies a basin [4], and it can be associated with petroleum sources, with approximately 10% of the world’s oil production linked to petroleum formed in lacustrine environments [5]. As integral components of the water cycle, lakes both influence and are influenced by socio-economic development and land use in their surrounding areas [6,7,8]. Despite their socio-economic contributions, many benefits derived from lakes used for hydropower are not directly perceived by local communities [9].

However, increasing population, urbanization, socio-economic development, agricultural intensification, and industrialization have led to the overexploitation of lakes [10,11]. Globally, lakes face critical challenges such as water quality degradation (eutrophication, pollution), water quantity reduction (erosion and sedimentation), and social conflicts over water use [12,13]. Environmental, socio-cultural, and economic factors influence the sustainability of lake ecosystems. Therefore, sustainable lake management must integrate these dimensions within a comprehensive and systemic framework, rather than through fragmented approaches [14]. This integration should align with the principles of sustainable development and the circular economy to ensure harmony between community development, economic growth, and environmental conservation [15,16,17]. Lake ecosystems are particularly vulnerable to overfishing and heavy metal pollution, which negatively impact fisheries and tourism, thereby affecting local economies [18]. Conversely, tourism development can exacerbate water resource management challenges [19]. Lake morphology, including water level fluctuations, significantly affects water storage, flood control, and aquatic biodiversity [20,21]. Sedimentation, a common issue in lakes, varies depending on its source [22].

Recent studies emphasize the importance of incorporating social aspects into sustainable lake management [23]. Social factors independently and interactively influence sustainability outcomes alongside ecological [24,25,26,27] and economic dimensions [28]. Human activities directly impact lake sustainability [29]. The effectiveness of lake management is often hindered by challenges such as limited data availability, lack of sectoral coordination, resource constraints, and policy or political issues [30,31]. Technological and infrastructure aspects, including environmental monitoring tools and fishing equipment, also play a crucial role in maintaining lake sustainability [32].

Lake Batur, located within the UNESCO Global Geopark, is a prominent tourist destination known for its natural beauty. Its ecosystem supports agriculture, settlements, livestock, and fisheries, serving as a water supply source and transportation route. Spanning 1600 hectares, Lake Batur holds substantial potential for annual fish production [33]. However, the lake has recently experienced significant environmental degradation and declining water quality [34]. In response, the Indonesian Presidential Regulation Number 60 of 2021 prioritizes Lake Batur’s restoration, focusing on pollution control from floating net cage (FNC) fisheries, agriculture, and other anthropogenic activities within the watershed [35]. The lake is particularly vulnerable to pollution from domestic waste, agricultural runoff, and unmanaged fishery operations, resulting in water quality levels that often exceed acceptable thresholds [36,37,38]. Additionally, fluctuating water levels contribute to periodic flooding, while regional tourism development remains stagnant due to inadequate planning and infrastructure.

Despite its ecological and economic importance, Lake Batur faces multifaceted sustainability challenges driven by environmental degradation, socio-economic pressures, and institutional limitations. The lack of integrated, data-driven management strategies has hindered effective restoration and policy implementation. This research is critical due to the continued environmental degradation and the socio-economic stagnation affecting the surrounding region. To address these issues, the study proposes the development of a sustainability index that encompasses environmental, economic, socio-cultural, infrastructure-technology, and institutional-management dimensions. This index will serve as a comprehensive tool to assess Lake Batur’s sustainability status and inform future restoration and management strategies. Furthermore, the integration of this index into a decision support system (DSS) aligns with contemporary research that emphasizes the role of DSS in facilitating evidence-based policymaking for sustainable lake management. By providing a structured framework for evaluating sustainability, the DSS can enhance stakeholder coordination, optimize resource allocation, and support adaptive management practices aligned with national restoration priorities.

2. Methods

2.1. Research Location

The study will take place at Lake Batur, located in the Kintamani District of Bangli Regency, Bali Province, Indonesia (see Figure 1). The lake is an active caldera, spans 15.91 km² with a water volume of approximately 815.38 million m³, an average depth of 50.8 m, and a 21.4 km coastline. It receives water from rain and mountain seepage, covering a catchment area of 106.35 km² [39].

Recognizing its ecological and socio-economic importance, the Indonesian government designated Lake Batur as one of fifteen national priority lakes under Presidential Regulation No. 60 of 2021 concerning the Rescue of National Priority Lakes. Nevertheless, the implementation of this policy at the regional level encounters significant challenges. These include inadequate coordination among relevant sectors such as environment, fisheries, energy, tourism, and agriculture, as well as limited participation of local communities, which collectively undermine conservation effectiveness. The policy framework remains predominantly top-down and has yet to completely incorporate participatory mechanisms that engage indigenous communities. Additionally, weak monitoring and enforcement of regulations addressing environmentally detrimental activities, including FNC fisheries and domestic waste disposal, have exacerbated the degradation of the lake’s ecosystem [40].

The population surrounding Lake Batur, particularly in Kintamani District, essentially comprises Balinese Aga or Bali Mula communities, who maintain robust local customs and value systems. They uphold the Subak system, recognized as a UNESCO World Heritage, which integrates spiritual, social, and ecological dimensions in water and agricultural management. Traditionally, Lake Batur is regarded as a sacred site closely linked to local mythology, such as the legend of Kebo Iwa. The presence of Ulun Danu Batur Temple and the practice of the Pakelem ritual exemplify the community’s reverence for the lake as both a vital life source and a spiritual symbol [41].

Land use within the Lake Batur catchment area is categorized into six types: protected forests, limited production forests, natural tourism parks, enclaves, water bodies, and other use areas. The predominant land use is “other use areas,” covering 4728.96 hectares (46.3%), followed by natural tourism parks (2211.84 hectares; 21.66%), water bodies (1606.45 hectares; 15.73%), protected forests (1051.04 hectares; 10.29%), limited production forests (415.54 hectares; 4.07%), and enclaves (198.13 hectares; 1.94%). The extensive presence of other use areas likely contributes to increased liquid waste inflow into the lake due to diverse human activities [42].

The Lake Batur ecosystem serves multiple functions. The terrestrial ecosystem supports settlements, agriculture, plantations, livestock, and tourism, while the aquatic ecosystem provides raw water, transportation, the FNC fishery system, fisheries, and tourism. The lake’s potential annual fish production ranges from 109.9 to 210.5 kg/ha, with an average of 120.4 kg/ha. Given its 1600-hectare surface area, the sustainable fish yield is estimated between 109 and 130 tons per year. However, fisheries data from 2022 indicate a production of 576 tons, substantially exceeding the estimated potential, primarily due to restocking initiatives and the proliferation of fast-growing fish species [40].

Increased nutrient levels and algal blooms have caused oxygen depletion, leading to large-scale fish deaths, decreased recreational value, and decreased clean water availability. Furthermore, the introduction and rapid expansion of non-native and invasive fish species over the past decade have posed significant ecological challenges [35,43]

2.2. Research Approach and Stages

This study employed the Multi-Aspect Sustainability Analysis (MSA) framework to assess the sustainability status of Lake Batur. Grounded in the Rapid Appraisal Process (RAP) methodology, MSA is particularly suitable for evaluating complex socio-ecological systems where quantitative data are limited and expert judgment is crucial. By integrating diverse expert perspectives across multiple sustainability dimensions—Environmental, Socio-cultural, Economic, Institutional-Management, and Infrastructure-Technology—MSA offers a comprehensive and robust assessment tool. The research process included careful development of Key Performance Indicators (KPIs) within each dimension, followed by systematic expert data collection, quantification, aggregation, and scoring in accordance with standard MSA procedures. Multiple iterations and stakeholder consultations were conducted to refine the indicators and ensure contextual relevance. Additionally, the approach incorporates validation steps such as random iterations to assess uncertainty and scenario analysis to project future sustainability statuses. This iterative, expert-driven methodology enables the model to be periodically updated and adapted, allowing for ongoing monitoring and informed decision-making in dynamic lake management contexts.

2.2.1. Data Collection, Respondent Selection and Data Validation

Data collection relied primarily on qualitative methods such as in-depth interviews, Focus Group Discussions (FGDs), and observations. Seventeen key stakeholders and experts were purposively selected based on their expertise and active involvement in Lake Batur’s management. This group included policymakers (national and regional governments), researchers (Udayana University, Indonesian National Research and Innovation Agency), business leaders (entrepreneurs in fisheries, farming, restaurants, and tourism), community representatives (cultural leaders), and NGOs (Batur Unesco Global Geopark), ensuring broad but relevant viewpoints.

An odd number of respondents was deliberately chosen to facilitate modus determination during data analysis, which is critical when applying the RAP principle in MSA. Respondents’ judgments on each indicator were collected using structured questionnaires and guided discussions.

To enhance data reliability and validity, triangulation was applied. Findings from expert opinions were cross-verified with existing literature and FGD results to ensure consistency and robustness. This multi-source verification helps reduce bias and strengthen the credibility of the sustainability assessment.

2.2.2. Data Analysis and Interpretation

Data analysis began by converting qualitative expert judgments into quantitative values using the mode—the most frequently assigned score among all expert assessments for each indicator. This approach follows the RAP principle integrated within the MSA framework. Using the mode ensures that the consensus view among experts is reflected while minimizing the influence of outliers. Indicators were scored on a predefined ordinal scale, typically ranging from 0 (bad) to 4 (good).

The analytical procedure proceeded in multiple stages. First, indicator scores that belong to the same factor were averaged to generate representative factor values. Each of these factor values was then normalized relative to its ideal maximum score, denoted as $G_{fn}$, by dividing the mode value of the factor Mo.fn by this maximum using Formula (1):

$$y_{fn} = {\displaystyle \frac{Mo.fn}{G_{fn}}}$$

(1)

where y is aspect status value, y_f is aspect factor, Mo is modus value on factor, G is the highest score (good) on the factor of the indicator assessment, and f is factor value.

The Aspect Status Value for each dimension was calculated by averaging these normalized factor values and multiplying the result by 100% as follows in Formula (2):

$$y = {\displaystyle \frac{\sum y_{fn}}{fn}}\times 100\%$$

(2)

This normalization standardizes the scores across different factors and dimensions, allowing for meaningful comparisons in the sustainability assessment.

Following this, the overall sustainability status of Lake Batur was determined by aggregating the Aspect Status Values across all five dimensions. In this study, a simple average was used, assuming each dimension is equally important. The aggregate sustainability score was calculated using Formula (3):

$$Y = {\displaystyle \frac{\sum y_n}{n}}$$

(3)

where Y is aggregate sustainability status value, y_n is the Aspect Status Value and n is the total number of aspects. This produces a comprehensive indicator representing the overall sustainability condition. Although a simple average was chosen for this study, weighted averaging may be employed in future analyses if stakeholders prioritize specific dimensions differently.

Additional analyses were performed to assess uncertainty and identify leverage factors. Uncertainty assessment was achieved through random iterations and calculation of error margins to evaluate the reliability of predicted sustainability outcomes, thereby enhancing confidence in the results. Leverage factors—indicators that have the greatest influence on sustainability scores—were identified to focus management efforts and inform scenario-based policy recommendations. The results were visualized using quadrant matrices, which integrate current and projected sustainability states to support effective prioritization and adaptive management strategies for Lake Batur.

Through this structured and systematic methodology (see Figure 2), which combines expert knowledge, data triangulation, and rigorous quantitative procedures, the study provides a robust and actionable framework for guiding long-term sustainable management of Lake Batur.

By systematically integrating expert judgment, empirical data, and sustainability principles, this approach provides a comprehensive framework for effective decision-making and the development of long-term management strategies for Lake Batur [18,44,45,46].

Figure 2. Research framework (modified from [45]).

Figure 2. Research framework (modified from [45]).

This study divides sustainability into four categories: Critical, Alert, Acceptable, and Ideal.

Table 1. Sustainability status criteria.

Value	Sustainability Status
<25	Critical
>25–50	Alert
>50–75	Acceptable
>75	Ideal

details the significance of each category. This four-tier system aligns with prior practices in Indonesia and allows for straightforward comparisons with earlier research on lakes like Danau Maninjau and Danau Ranau [47,48]. Although intermediate states exist along the sustainability spectrum, they are included within the range between classes 2 (Alert) and 3 (Acceptable) and can be further clarified in future work.

After each aspect’s assessment, each factor’s sustainability value was plotted into an 8-quadrant matrix to give a clear view of Lake Batur’s sustainability status (see Figure 3). The assessment for each condition based on coordination is as follows:

• Quadrant I (Good): This condition is desirable as it indicates a positive value, with both the x-axis and y-axis values exceeding 50. Therefore, maintaining this condition is crucial for further improvement
• Quadrant II (Priority): Despite the x-axis value being above 50, the y-axis value below 50 indicates a potential decline. Thus, support and attention are necessary in this quadrant.
• Quadrant III (Important): Despite a reduced x-axis value below 50, the y-axis value exceeding 50 indicates potential improvement, necessitating immediate action.
• Quadrant IV (Urgent): This condition is unexpected, with both x-axis and y-axis values below 50. Urgent action is needed to prevent further declines.
• Groups V to VIII are due to high uncertainty; this condition is unsuitable. If it falls into this category, expert clarification on future values is needed to avoid bias and ensure usability.

When making policy decisions, address adverse conditions in Groups IV, III, II, and I.

3. Results

3.1. Result in Sustainability Status

The KPI-based lake sustainability index consists of five aspects, each with sub-aspects, factors, and indicators. The indicators based on KPIs for sustainable lake management are outlined in

Table 2. Aspects and factors that affect the condition of Lake Batur.

Code/Economic (Bad–Good Score)	Code/Environmental (Bad–Good Score)	Code/Social-Cultural (Bad–Good Score)	Code/Institutional-Management (Bad–Good Score)	Code/Infrastructure-Technology
Ec1. Monthly income of residents around the lake (<IDR 2.5 million to >IDR 7.5 million)	Ev1. Variety of fish species in the Lake (H’ < 1 (low) to H’ > 1 (high)	SC1. Percentage of residents’ livelihoods in surrounding sub-districts that depend on the lake. (<25% to >75%)	IM1. Availability and enforcement of regulations for national lake management. (None–Implemented)	IT1. Lake infrastructure monitoring equipment. (None–Exist and functional)
Ec2. Monthly income of households in the main community around the lake (<IDR 2,500,000/household/month to >IDR 2,500,000/household/month	Ev2. The existence of invasive fish in the lake. (Exist–None)	SC2. Percentage of villages bordering the lake in the sub-district. (<25% to >75%)	IM2. Availability of regional lake area management regulations. (None–Regional regulation implemented)	IT2. Environmental monitoring devices for lake areas. (None–Exist and functional)
Ec3. Development of small and medium enterprises in the lake area (Reduced number (in the last 5 years) to Increase in number (in the last 5 years))	Ev3. The presence of fishery reserves in the lake (Established–None)	SC3. Differences of interest were discussed at Indigenous community meetings. (Exist–None)	IM3. Lake area spatial planning and lake water zoning (None–Zoning Already set)	IT3. Lake water sedimentation prevention device (None–Exist and functional)
Ec4. The income disparity in the lake community over the last five years (High inequality to Low Inequality)	Ev4. The existence of protected lake fish species (Exist–None)	SC4. Conflicts regarding customary rules and formal rules (Exist–None)	IM4. Regional regulations regarding waterfront and lakeside buildings (None–Exist and Optimal)	IT4. Lake area erosion control device (None–Exist and functional)
Ec5. Percentage of tourism sector income to regional revenue/gross regional domestic product (Less than 25% to More than 75%)	Ev5. The presence of FNC in the lake (Very disturbing–No FNC)	SC5. Incidents of societal conflict over the past five years (Exist–None)	IM5. Regional regulations regarding lake usage permits (None–Exist and Optimal)	IT5. The use of information technology (ICT) in integrated lake management (None–E-tourism available)
Ec6. Origin area for lake tourism visitors (Local to Foreign)	Ev6. Water quality assessment according to the STORET method (Heavily polluted to Meets the quality standard)	SC6. The majority of lake residents have attained the highest level of formal education. (Primary School–High School/equivalent)	IM6. Regulations regarding transportation on lakes (None–Exist and Optimal)	IT6. Utilization of information and communication technology (ICT) in the development of tourism in lake areas. (None–Exist and functional)
Ec7. Average monthly tourist visits to the lake (<2000 people to >5000 people)	Ev7. Assessment of water quality using the Pollution Index (PI) method (Heavily contaminated to Meets the quality standard)	SC7. The public’s understanding of the importance of preserving lakes. (<30% to >60%)	IM7. Regulations regarding lake tourism in the region. (None–Exist and Optimal)	IT7. The use of renewable energy in the lakeside region (None–Exist and functional)
Ec8. Average daily expenses per tourist in the lake area. (<IDR 500,000 to >IDR 1,500,000)	Ev8. Trophic status of lake waters (Hypertrof to Oligotrophic)	SC8. Engagement of the community in environmental education related to the lake <10% of the population to >30%)	IM8. Regional regulations for managing FNC fish cultivation (None–Exist and Optimal)	IT8. Hydropower renewable energy production device (None–Exist and functional)
Ec9. The typical duration of tourist stays in the lake area (<1 Day to >2 Days)	Ev9. Frequency of flooding in the lake’s catchment area (>5 times a year to Never floods)	SC9. Community involvement in the management programs for the lake’s catchment area (None to Routinely involved)	IM9. Regional waste management rules (None–Exist and Optimal)	IT9. Availability of centralized parking area (None–Suitable)
Ec10. Average monthly cultural and arts events in the lake region (<2 times to >5 times)	Ev10. The Area of inundation the lake’s catchment area. (>10% to No Inundation)	SC10. Engaging the community in the upkeep of the lake area (None to Routinely engage)	IM10. Regulatory guidelines for managing domestic and commercial waste in lakes. (None–Exist and Optimal)	IT10. The presence of a buffer zone around the lake area. (None–Suitable)
Ec11. Potential fish yield from lake capture fisheries (<IDR 2.5 Million/month to >IDR 5 Million/month	Ev11. The forested area is inside the lake’s catchment region (<30% to >50%)	SC11. Community empowerment initiatives around the lake over the past five years (None–>5 Community program)	IM11. The central government’s responsibility regarding lake management funding (None–Exist and Optimal)	IT11. Prohibited fishing device usage (Exist–None)
Ec12. Fish distribution and marketing (Local to International/Expoerted)	Ev12. The amount of green open space in the lake’s watershed. (<30% to >50%)	SC12. Community engagement in empowerment initiatives around the lake (low–High)	IM12. The central government’s role in managing lake resources. (None–Exist and Optimal)	IT12. Management of riparian vegetation in lakes (None–Intensive)
Ec13. Income generated from fish farming serves as the primary source of revenue for many community members. (<IDR 2.5 million/month to >IDR 5 million/month)	Ev13. Proportion of developed land in the lake’s catchment area. (<50% to >30%)	SC13. The proportion of business actors among residents (<30% to >60%)	IM13. The role of local government funding in lake management (None–National State Budget and Assistance available)	IT13. Conservation initiatives for lake regions (None–Continuous)
Ec14. Fishing serves as the main livelihood for the community. (<50 Fishermen to >200 Fishermen)	Ev14. Erosion rate in the lake catchment area (High to Low)	SC14. The empowerment of traditional institutions. (None–Exist and Optimal)	IM14. The role of local government in lake management (None–Local government Budget and Assistance available)
Ec15. Earnings from fishing as the primary occupation (<IDR 2 million to >IDR 5 million)	Ev15. Lake sedimentation and shallow levels (>5 cm/year to <1 cm/year)	SC15. The role of local leaders in raising awareness and promoting lake maintenance. (Low Role to High Role)	IM15. Participation of business/private actors (None–Routinely participate)
Ec16. Fish production in the lake during the past five years (Decrease to Increase)		SC16. Culture of cooperation among lakeshore communities (Low–High)	IM16. The involvement of academics and researchers (Low–High)
Ec17. Distribution of horticultural products from the lake region (Local to International/Expoerted)		SC17. The presence of traditional practices and local knowledge for maintaining lakes (None–Exist)	IM17. Stakeholder collaboration and program alignment for lake management (None–Routinely)
Ec18. Horticultural agriculture-focused local economic development in the lake region (None–High)		SC18. Customary rules against degrading lake ecosystems (None–Exist and Obeyed)	IM18. Presence of the Tourism Awareness Group (Pokdarwis) (None–Exist and Active)
Ec19. Investment by domestic companies for economic development in the lake area. (None–Large Companies)
Ec20. Investment from foreign companies for economic development in the lake area. (None–Large Companies)

, based on selecting indicators derived from existing criteria, discussions with experts, and secondary data analysis.

The analysis results from the KPIs in Figure 4 show that Lake Batur’s current condition is in the alert category (41.9 out of 100 or 41.9/100). All aspects of Lake Batur are included in the “alert” category except for the social-cultural aspect (acceptable).

Infrastructure and technology are the weakest performance aspects, scoring only 34.62/100. This indicates limited infrastructure to protect the lake’s condition. Additionally, minimal information and communication technology (ICT) integration is required to support lake management and the tourism sector.

Similarly, the environmental aspect is in second position, with a weak performance (37.73/100). Water quality and pressure on land are problems that are increasing every year. Institutional and management aspects are also weak, with points in the management of Lake Batur (37.94/100). The absence of an institution that acts as a leading sector and is responsible for the sustainability of Lake Batur makes it challenging to manage the lake. The economic aspect that relies on tourism and fisheries factors has not developed much, as shown by a still low value of 44.6/100. The socio-cultural aspects owned by the local community have the highest performance among other aspects and are categorized as acceptable (54.61/100). This aligns with the Balinese people’s renowned high social cohesion, which can be leveraged for future lake management.

The sustainability status for each aspect of Lake Batur has been evaluated by projecting both current (X-axis) and future (Y-axis) performance values within an 8-quadrant matrix, as shown in Figure 5. This approach helps clarify priority areas and guides targeted intervention strategies. The explanation of these quadrants can be seen in Figure 5, which visually presents the current sustainability scores and future trend projections for each aspect.

For the Institutional aspect, the present value is measured at 37.94, while the projected trend is 49.84. As both figures fall below the critical threshold of 50, the institutional framework faces an “urgent” situation. Immediate and decisive interventions are necessary to strengthen existing institutions and prevent further deterioration in governance and management structures.

The Economic aspect also presents significant concerns. With a current sustainability value of 44.64 and a projected future value of just 9.85, this domain is categorized as highly “urgent”. Economic sustainability is at considerable risk of further decline, underscoring a pressing need for comprehensive improvement measures to prevent systemic setbacks and ensure resilient livelihoods around Lake Batur.

Regarding the Environmental aspect, the current measurement stands at 37.73 with a forward-looking trend of 43.33. Both values are below the sustainability threshold, indicating that environmental conditions are fragile and trending downward. Without prompt remedial action, further ecological degradation is likely. It is essential to adopt immediate strategies aimed at reversing negative environmental trends and sustaining the ecosystem of Lake Batur.

For the Social and Cultural aspect, the assessment reveals a current value of 54.61—comfortably above the threshold—while the projected value is slightly lower at 49.84. This quadrant placement highlights that, although present social and cultural sustainability is relatively strong, there is a looming risk of decline. Targeted policy support and proactive measures should be prioritized to maintain and enhance these conditions, minimizing the risk of slipping into an urgent category in the future.

Lastly, the Technology and Infrastructure aspect yields a current value of 34.62 with a future trend precisely at 50.00. This result falls within a high-uncertainty zone, indicating that further expert analysis is needed. Such uncertainties must be resolved through additional research and stakeholder consultation, ensuring any policy recommendations are both robust and objective.

By structuring the assessment in this manner, decision-makers are empowered to prioritize interventions according to the most pressing needs and uncertainties in Lake Batur’s sustainability profile. This enables a focused approach, maximizing the effectiveness of future sustainability strategies.

3.2. Aspect Status

Following the presentation of the overall sustainability analysis, which classifies Lake Batur in the “Alert“ category, this section will elaborate on the status and condition of each of the five key sustainability aspects: economic, environmental, socio-cultural, institutional and management, and technology and infrastructure. Each subsequent subsection provides a detailed examination of the key findings, assigned scores, specific challenges faced, and the rationale behind the determined status of each aspect. This detailed breakdown offers a comprehensive understanding of the dynamics and priorities necessary for enhancing the future management of Lake Batur.

3.2.1. Economic Sustainability Status

Lake Batur’s economic sustainability result is currently classified as “Alert“, indicating stable yet suboptimal conditions (score below 75). The local economy is predominantly tourism-driven, with most households earning between IDR 2.5 million and IDR 5 million per month [49]. However, short tourist stays (1–2 days) and limited cultural attractions (less than twice a month) restrict income growth [50,51,52,53]. MSME development has remained stagnant over the past five years, and moderate-income inequality persists due to unequal access to education, capital, and business opportunities. Diversification into agriculture and handicrafts is urgently needed to enhance economic resilience, especially in light of vulnerabilities exposed during the COVID-19 pandemic.

Tourism contributes 25–50% to Bangli’s PAD and PDRB, with over 5000 monthly visitors spending IDR 500,000–750,000 daily [50,51,54]. Fisheries yield 50–100 kg/ha/year, supporting 50–200 fishermen earning IDR 2–5 million monthly, with stable productivity over five years [33]. Agricultural products, particularly horticulture, reach provincial markets, though infrastructure and market access remain limiting factors. Investment is dominated by domestic medium-sized enterprises, with no foreign investment recorded, indicating a need for improved regional appeal and policy support. Strategic actions—such as regulating land use, enhancing infrastructure, and promoting sustainable tourism and fisheries—are essential to prevent economic decline and unlock Lake Batur’s full development potential.

3.2.2. Environmental Sustainability Status

Lake Batur’s environmental sustainability is critically low, with weak performance across most sub-aspects and a Y value below 50, indicating an urgent need for intervention. Fish species diversity is moderate, as indicated by the Shannon–Wiener index, with no endangered species identified [51]. However, invasive species remain unmanaged, and floating net cages (FNCs) exceed regulatory limits, reducing fish production potential [40,43]. Water quality is deteriorating, with pollution levels classified as Hypertrophic due to agricultural runoff and FNC activities [35,37]. Water quantity issues include annual flooding (1–5 times/year) affecting less than 10% of the watershed, which is driven by lake bottom siltation and increased runoff.

Beyond the multi-aspect sustainability indicators, critical basic limnological parameters serve as fundamental early warning indicators for the ecological health of Lake Batur. An assessment of its trophic status reveals key insights from data on water transparency, dissolved oxygen (DO), and nutrient levels. Specifically, water transparency data show fluctuations over recent years: 1.5 m in 2023, 17.48 m in 2022, and 0.4 m in 2021, compared to a quality standard of 10 m. Dissolved oxygen levels typically range between 4.6 and 7 mg/L, while average phosphate concentrations are recorded at 0.04 mg/L, exceeding the quality standard of 0.01 mg/L. These specific values, when collectively evaluated against their respective quality standards, provide a direct indication of the lake’s trophic state and highlight areas requiring urgent management attention, functioning as essential early warning signals for potential ecological imbalances [33].

Land use pressures are evident, with forest cover and green open spaces below 30% and declining, while developed land remains under 30% [21]. Erosion and sedimentation are moderate, with sediment accumulation at 1–5 cm/year, exacerbated by reduced vegetation cover. Preservation efforts must raise awareness, reduce FNC density through zoning, promote organic farming, and control land use changes. Activating the Lake Batur Working Group and offering economic alternatives to local communities are essential to support sustainable environmental management and mitigate further degradation.

3.2.3. Social and Cultural Sustainability Status

The socio-cultural sustainability of Lake Batur is moderately accepted, with a score of 54.61, reflecting the community’s partial engagement in lake conservation. Around 25–50% of the population in surrounding districts depends on the lake, though fewer than 25% of villages directly border it. Conflicts in lake management are minimal, with traditional meetings resolving differing interests and no significant disputes between customary and formal regulations. Most residents have at least a high school education, and awareness of lake conservation is moderate, though participation in outreach remains limited. Community involvement in lake maintenance is sporadic, indicating potential for more structured and sustained engagement.

Empowerment programs are scarce, with fewer than five implemented in the past five years, despite over 60% of business operators being residents. Traditional institutions are underutilized, although local leaders play a significant role in mobilizing conservation efforts. Cultural practices such as gotong royong and local wisdom exist but are only moderately applied, and customary rules against ecosystem destruction are rarely enforced. Strengthening community empowerment, enhancing the role of traditional institutions, and revitalizing cultural conservation practices are essential to improve socio-cultural sustainability around Lake Batur.

3.2.4. Institutional and Management Sustainability Status

Lake Batur’s institutional and management sustainability is in the “Alert” category, with a Y value below 50, indicating an urgent need for regulatory and governance improvements. Although Presidential Regulation No. 60/2021 provides a national framework for lake management [55], its implementation remains weak. Regional regulations exist but are inadequately enforced, and critical sectoral regulations—such as those governing lake boundaries, FNC permits, and spatial planning—are either lacking or poorly implemented [30]. This regulatory gap increases the risk of environmental degradation and stakeholder conflict. Effective lake management requires comprehensive regulations, improved supervision, stakeholder coordination, infrastructure development, and public engagement.

Government involvement is limited, with central support primarily in the form of funding through APBN, lacking structured guidance and oversight. Local governments face resource constraints in funding, expertise, and technology, necessitating stronger collaboration with central authorities and external stakeholders. Stakeholder participation, including the private sector, academia, and community groups like Pokdarwis, is irregular and underutilized. Forums and partnerships are conducted incidentally, and community-based tourism management remains inactive. Strengthening stakeholder coordination, reactivating community groups, and enhancing institutional capacity are essential to improve governance and ensure sustainable management of Lake Batur.

3.2.5. Technology and Infrastructure Sustainability Status

Technology and infrastructure are critical for sustainable lake management, yet Lake Batur scores lowest in this aspect, indicating severe deficiencies [56]. No sedimentation or erosion prevention tools exist, and ICT is not utilized in tourism development or integrated lake management. While monitoring devices for water levels, irrigation, and pollution are installed and functioning, they are not designed to improve lake conditions. Supporting infrastructure is also lacking—renewable energy systems are absent, centralized parking and buffer zones are inadequate, and buildings encroach upon the lake’s edge, reflecting poor enforcement of spatial regulations.

Fishing practices are relatively compliant, with minimal use of illegal gear; the dominant method remains FNCs. However, riparian management and conservation efforts are insufficient and unsustainable. To improve this aspect, interventions should include installing erosion control systems, integrating ICT and GIS for lake monitoring, and applying remote sensing to track eutrophication and water quality [55,56,57]. Advanced tools like real-time hydrodynamic simulations and early warning systems can support proactive, data-driven lake management and enhance environmental, social, and economic outcomes.

4. Discussion

Lake Batur has unique features that set it apart from many lakes worldwide, especially its volcanic origin, shaped by the active Mount Batur, and its semi-enclosed structure, which lacks a natural outlet. These elements influence its hydrological and ecological processes in a distinctive way. Moreover, traditional Balinese wisdom and customs play a crucial role in the community’s governance and management, highlighting socio-cultural factors that are less common elsewhere. While the KPIs provided here offer a universal framework for assessing sustainability, they are adaptable to Lake Batur’s specific ecological, hydrological, and socio-cultural conditions. This context helps place our findings within both universal and site-specific aspects of lake management, guiding the upcoming leverage factor analysis and development of customized management strategies scenarios.

4.1. Leverage Factor Analysis

The current performance of various sustainability aspects of Lake Batur requires significant improvement to prevent further environmental degradation. The lake’s status is currently at an alert level, indicating that its condition may deteriorate further without prompt and effective interventions, potentially leading to critical ecological and socio-economic consequences.

To identify the most influential factors affecting the lake’s sustainability, a sensitivity analysis was conducted within the MSA framework. This analysis calculates the environmental sustainability status and highlights factors that exhibit high sensitivity to changes in overall sustainability levels. The factors with the highest sensitivity max (green bars) and sensitivity value (yellow bars)—as shown in Figure 6—are considered the most impactful. These factors, referred to as driving factors, serve as priority targets for management efforts because improving them is expected to yield the most significant positive effect on Lake Batur’s sustainability.

Based on these driving factors, scenarios for enhancing the lake’s sustainability were developed.

Table 3. Priority factors for each aspect that can improve Lake Batur’s sustainability status.

No	Aspect/Factor	Good Value	Real Value	Scenario 1	Scenario 2	Existing Value	Value Scenario 1	Value Scenario 2
Economic
1	Ec 9	2	0	2	-	44.6	54.6	64.6
2	Ec 10	2	0	2	-
3	Ec 7	2	0	-	2
4	Ec 16	2	0	-	2
Environmental
1	Ev11	2	0	2	-	37.73	51.07	64.4
2	Ev5	2	0	2	-
3	Ev12	2	0	-	2
4	Ev8	3	0	-	3
Social-Cultural
1	SC3	1	0	1	-	54.61	60.17	65.72
2	SC15	2	1	2	2
3	SC10	2	1	-	2
Institutional-Management
1	IM5	2	0	2	-	37.94	49.06	60.17
2	IM12	2	0	2	-
3	IM4	2	0	-	2
4	IM8	2	0	-	2
Infrastructure-Technology
1	IT5	3	0	1	-	34.62	39.69	60.31
2	IT3	3	0	1	-
3	IT5	3	0	-	3
4	IT3	3	0	-	2
5	IT7	3	0	-	2
6	IT6	3	0	-	3
Total Average						41.9	50.92	63.04
Sustainability Status						Alert	Alert	Acceptable

and Figure 7 present the prioritized factors across five key aspects: Economic, Environmental, Socio-Cultural, Institutional-Management, and Infrastructure-Technology. Each factor’s current (real) value, target (good) value, and projected improvements under different scenarios are detailed, demonstrating potential pathways to elevate the lake’s sustainability status from alert to acceptable.

Figure 6 presents the sensitivity values for each sustainability aspect and its corresponding factors, illustrating their relative impact on the overall sustainability index of Lake Batur. These values highlight which factors significantly influence the lake’s sustainability status and thus serve as critical leverage points for targeted interventions.

The sensitivity leverage analysis has identified the most impactful factors affecting the sustainability of Lake Batur across five key aspects. In the economic aspect (Figure 6a), Ec9 (average length of stay of tourists), Ec10 (average monthly cultural arts events), Ec7 (average tourist visits), and Ec16 (fish production) emerge as highly influential, highlighting the intertwined importance of tourism development and fisheries for local livelihoods. Environmentally (Figure 6b), Ev11 (forest area in catchment), Ev5 (existence of FNC), Ev12 (green open space in catchment), and Ev8 (trophic status) are critical, emphasizing the direct link between land use practices in the surrounding area and the lake’s ecological health. Socially and culturally (Figure 6c), SC3 (incidents of interest differences at indigenous community meetings), SC15 (role of local figures in raising awareness), and SC10 (community participation in maintaining the lake) underscore the significance of social cohesion, traditional knowledge, and community engagement. Furthermore, institutional and management (Figure 6d) effectiveness is heavily influenced by IM5 (regulations on lake utilization permits), IM12 (role of central government in management), IM4 (regulations on waterfront and lakeside buildings), and IM8 (regulations on FNC fish cultivation), pointing to the necessity of robust governance frameworks. Lastly, in infrastructure and technology (Figure 6e), IT5 (use of ICT in integrated lake management), IT3 (lake water sedimentation prevention device), IT7 (use of renewable energy), and IT6 (use of ICT in developing lake tourism) indicate that technological adoption and sustainable infrastructure are vital for effective monitoring, preservation, and development.

Building on this analysis, Table 3 simulates priority factors within each aspect that could improve Lake Batur’s sustainability status, detailing their current and projected values under two proposed management scenarios. The scenarios simulate potential enhancements by adjusting these key factors toward their optimal targets, resulting in a progressive increase in the total average sustainability index from 41.9, categorized as a “alert” status, to 50.92 and 63.04, both within the acceptable range under Scenario 1 and Scenario 2, respectively. This integrated assessment highlights the importance of focusing on these leverage factors to advance Lake Batur’s sustainability effectively.

Figure 7 illustrates a simulation of Lake Batur’s sustainability status under multiple management scenarios, highlighting the potential improvements achievable by addressing the identified leverage factors. This simulation visually demonstrates how targeted interventions in key areas—such as environmental restoration, economic development, social engagement, institutional management, and technological infrastructure—can progressively enhance the lake’s overall sustainability. By comparing the outcomes of different scenarios, stakeholders can better understand the effectiveness of various strategies and prioritize actions that yield the most significant positive impact on Lake Batur’s ecological health and socio-economic well-being.

4.2. Proposed Management Scenarios

4.2.1. Economic Aspects Scenario

In Scenario 1, the economic sustainability value increased to 54.6 by extending tourists’ average length of stay and developing cultural arts attractions, thereby enhancing tourist appeal and experience. Scenario 2, on the other hand, raised the economic sustainability value to 64.6, driven by higher monthly tourist visits and increased fish production. Implementing these two scenarios aims to elevate Lake Batur’s status from “alert” to “Acceptable,” thereby improving its sustainability status.

Scenario 1 aims to extend tourists’ stays beyond one day by enhancing accommodation, promoting tour packages that combine natural and cultural attractions, and developing activities such as trekking and historical tours. Additionally, the frequency of cultural arts events should increase from twice a month to over five times, featuring dance festivals, traditional music concerts, and handicraft exhibitions. Involving local communities in these events will boost tourist appeal and support regional economic growth, making Lake Batur a more attractive destination.

Scenario 2 aims to increase monthly tourist visits to the Lake Batur area from fewer than 2000 to more than 5000 while also enhancing fish production. This necessitates an effective marketing strategy, which includes promotional campaigns that showcase Lake Batur’s uniqueness, natural beauty, and activities. Partnering with travel agencies and online platforms will improve visibility and boost revenue from tickets, tours, and other services.

Optimizing aquaculture practices and fisheries management is crucial to reversing the decline in fish production. This includes utilizing the latest fish farming technologies, improving the management of fish stocks, and implementing effective restocking programs. Increased fish production will bolster the local economy through fish sales and create opportunities for expanded fish exports. These enhancements will establish the fisheries sector as a key economic foundation for the Kintamani District, improve local community welfare, and elevate tourist appeal.

Implementing these economic sustainability scenarios involves complex challenges that require integrated strategies. Both scenarios face technical hurdles related to infrastructure and technology: Scenario 1 struggles with limited tourism infrastructure and a shortage of skilled workers in the tourism and cultural sectors, while Scenario 2 faces issues with inefficient visitor management and fish farming technology. Addressing these needs targeted investments in tourism workforce training, infrastructure development—including accommodations and arts facilities—upgrading aquaculture technology, and digital systems for booking and monitoring visitors. Economically, challenges include scarce investment for tourism and cultural projects (Scenario 1), fluctuating fish market prices, over-dependence on tourism without income diversification, and uneven economic benefits between large firms and local communities (Scenario 2). Solutions require promotional funding, incentives for local investors, financing models for tourism infrastructure, micro-capital for fishermen, and investments in fish processing. Social concerns involve low engagement of local MSMEs in tourism (Scenario 1) and possible social conflicts from community exclusion and environmental issues (Scenario 2). Necessary resources include community support, entrepreneurship training, and collaborative programs involving fishermen, tourism stakeholders, and village authorities to promote fair benefits. Politically, both scenarios face obstacles like weak coordination between local government and tourism sectors (Scenario 1) and the lack of local regulations supporting sustainable tourism and fisheries integration (Scenario 2). These require policies that foster tourism growth, cross-sector collaboration for lake governance, and incentives for local priority sectors. Risks include over-tourism, environmental harm, supply-demand mismatches, overreliance on specific industries, social discord, and potential regulatory erosion resulting from conflicting sectoral interests.

4.2.2. Environmental Aspects Scenario

In scenario 1, environmental improvements focus on “Forest Areas” and “FNC.” The goal is to increase forest coverage from less than 30% to over 50% of the watershed area. For FNC, the aim is to reduce their numbers to below the specified limit to minimize disturbance to the lake waters. Enhancing sustainability involves directly managing these factors through targeted activities described as follows:

• Enforcing existing regulations is essential for maintaining the current forest area and preventing its reduction. Additionally, controlling the number of FNCs is crucial to avoiding lake pollution.
• Preventing forest encroachment is essential for preserving the existing forest area; regular monitoring can accomplish this. Furthermore, addressing the rise in FNCs demands a multifaceted approach, including regulations, institutional support, and community engagement.

Addressing the current condition is essential. Restoring forest damage can be accomplished through reforestation programs and by enhancing the management of existing FNCs, which includes improved feed and fish waste control.

In Scenario 2, environmental improvements focus on green open spaces and trophic status, which are key sustainability indicators. The goal is to increase green open space from less than 30% to over 50% and to enhance a more favorable trophic level status. These improvements can be achieved through targeted activities such as:

• Preventing erosion and flooding is essential to controlling the quality of existing green open spaces and improving the water quality entering the lake. Additionally, monitoring the lake’s trophic status and addressing the sources of any issues are crucial.
• Preventing green open spaces from being converted into built land is crucial. This action helps to stop sediment and pollutants from entering water bodies, which can negatively impact the lake’s trophic status.

Effective prevention measures are essential, as are management with improvement efforts, including increasing and enhancing green open spaces to filter water entering the lake. Improving the lake’s trophic status also involves initiatives to enhance water quality.

Implementing these environmental improvement scenarios involves multiple challenges across different areas. Technically, both scenarios face hurdles due to the absence of specific regulations needed for their goals—whether it is increasing forest cover and controlling FNCs in Scenario 1 or monitoring and managing green open spaces and lake water quality in Scenario 2. This situation consistently demands human resources with adaptable skills for livelihood changes (Scenario 1) or specialized expertise for comprehensive monitoring and control (Scenario 2), risking gaps in current human resource capabilities. Economically, substantial costs are expected, such as managing community income reductions (Scenario 1) or funding extensive monitoring efforts (Scenario 2). These initiatives require large program budgets, with risks amplified by limited government budgets and low private sector investment. Socially, both scenarios require broad community consensus, effective socialization, and ongoing education to ensure support and participation. Without these, social conflicts and failure to reach vital agreements are likely. Politically, the main challenges involve establishing solid institutional frameworks and clear authority divisions, which depend on widespread political agreement. The main political risk is the potential failure to regulate institutions effectively and to distribute authority properly, which could undermine the successful implementation of these crucial environmental strategies.

4.2.3. Social and Cultural Aspects Scenario

The focus in Scenario 1 is on reducing conflicts and increasing consensus among different societal elements through regular meetings of indigenous peoples. These meetings serve as forums to reconcile differing interests and build consensus on mutually acceptable solutions. Additionally, optimizing the contribution of lakeside villages to boost local participation and empowerment. Activities include mapping and identifying the potential of these villages to enhance their involvement in environmental conservation and local economic empowerment. This approach ensures that villages are more empowered to participate in the sustainable management of lake resources.

In Scenario 2, local actors’ roles are strengthened through training and workshops, while environmental awareness campaigns engage all societal levels. These efforts enhance local leaders’ capacity to lead and organize lake conservation initiatives and encourage broader community participation. The activity plan includes training and workshops for local leaders to equip them with the knowledge and skills needed for effective and sustainable environmental programs. Additionally, environmental awareness campaigns involve the entire community around the lake, highlighting the importance of their participation in maintaining the lake’s sustainability. These activities are interconnected, with local leaders driving broader and deeper community involvement.

Both scenarios demonstrate that appropriate interventions can enhance Lake Batur’s social sustainability. Active involvement from local leaders and the community is crucial for long-term sustainability. Therefore, collaboration among the government, community, and other stakeholders is essential to developing Lake Batur’s holistic and sustainable management strategy.

However, the successful implementation of these social sustainability interventions is consistently challenged by underlying structural and cultural issues within the community, which must be systematically addressed.

Achieving social sustainability in Lake Batur’s management is a complex effort filled with major challenges across technical, economic, social, and political aspects. Socially, key hurdles include low, inconsistent community participation leading to diminished local ownership, the decline of invaluable local wisdom and traditional practices, and the erosion of collective environmental responsibility. These are compounded by the limited reach and inclusivity of empowerment programs, resulting in underdeveloped community skills and restricted access to vital education, alongside spatial disparities in access and involvement. Addressing these requires dedicated efforts in community mobilization, programs to revive traditional knowledge, inclusive training, and improved access to information, otherwise risking continued low ownership, persistent social conflicts, and community disempowerment. Politically, the principal challenge is the lack of synergy between customary norms and formal regulations, which leads to weak enforcement of traditional rules and the underutilization of customary institutions, often causing normative conflicts. Overcoming this demands collaborative policies that bridge these systems, strengthening both traditional and formal local institutions, and actively including customary leaders and residents in governance to mitigate risks of weak governance and fragmented efforts. Technically, the absence of structured participatory mechanisms, difficulty in integrating traditional knowledge, and challenges in consistent program delivery pose significant obstacles, necessitating the development of formal systems and platforms for knowledge integration, with the risk of ineffective program implementation. Economically, uneven distribution of benefits and the under-resourcing of community programs are critical issues, requiring dedicated funding for inclusive empowerment initiatives and equitable benefit-sharing mechanisms, as economic inequality could otherwise reduce participation and exacerbate social disparities. Overall, these interlinked challenges underscore the critical need for a comprehensive, integrated approach to foster genuine social sustainability.

4.2.4. Institutional and Management Aspects Scenario

In Scenario 1, interventions focus on the availability and implementation of lake area regulations and the government’s role in achieving an acceptable sustainability status. Survey results indicate a lack of regional regulations for lake use permits. Therefore, strategic steps include preparing a special regional government Regulation (Perda) involving experts, community participation, and stakeholders. During the drafting process, the government can establish temporary guidelines to regulate activities around the lake, limiting negative impacts and ensuring sustainability. Additionally, the government can supervise and enforce existing laws on lake activities, imposing sanctions for violations to maintain control and promote sustainability.

Several steps can be taken to address the limited role of the central government in lake management. Establish a lake management institution involving the government, community, and private sector to oversee activities, issue permits, and coordinate conservation programs and regulatory enforcement. The government can collaborate with environmental institutions, universities, and NGOs to research, monitor, and evaluate lake management. Additionally, educating the community about the importance of lake management and its environmental impact will raise public awareness and help reduce harmful activities.

In Scenario 2, the local government can address the lack of regional regulations for building constructions on or near Lake Batur by formulating technical regulations based on the Ministry of PUPR Number 1085/2023, involving experts, community participation, and stakeholders. Additionally, the government can supervise and enforce existing laws, imposing sanctions for violations to ensure compliance and sustainability.

To manage fish farming with FNC, the government has prepared a special regional government regulation (Perda) with input from experts and stakeholders. The strategy includes reducing FNC use and recommending a switch to capture fisheries to mitigate environmental impacts. While regulations are being developed, the government can enforce existing laws on lake activities to ensure compliance and sustainability.

Implementing institutional interventions in Scenario 1 and Scenario 2 presents multifaceted challenges related to regulatory development, coordination, and enforcement. Technically, drafting and enacting regional regulations such as the special government Regulation (Perda) and technical guidelines requires professional involvement and extensive stakeholder consultation, which can be time-consuming and complex. Economically, resources must be allocated for institutional capacity building, legal processes, and ongoing supervision to ensure effective enforcement and sanctioning mechanisms. Social challenges include fostering meaningful community participation, raising public awareness, and managing potential resistance to new regulations or changes in traditional practices. Politically, aligning interests among various government levels, private sector, and community groups, while establishing new lake management institutions, demands strong leadership and cooperation to overcome bureaucratic inertia and possible conflicting agendas. Risks include delayed or ineffective regulation implementation, weak enforcement undermining compliance, and fragmented management efforts leading to suboptimal sustainability outcomes. Overcoming these challenges requires integrated planning, sustained funding, institutional collaboration, and continuous education to empower all stakeholders and secure long-term governance success for Lake Batur.

4.2.5. Infrastructure and Technology Aspects Scenario

Scenario 1 focuses on enhancing the use of ICT as an integrated lake management tool. This involves implementing a real-time monitoring and reporting system accessible to all stakeholders. Physical infrastructure can be monitored through CCTV, with footage available for stakeholders. Additionally, devices for monitoring water quality and quantity, such as a sediment trap, can significantly enhance the sustainability assessment of Lake Batur. Further advancements in infrastructure and technology are crucial for improving this sustainability assessment.

Scenario 2 introduces additional elements that can enhance sustainability value. In the first scenario, ICT is an integrated lake management tool and sediment trap. In the second scenario, these two devices are expected to manage Lake Batur to boost its sustainability value effectively. Furthermore, the presence of infrastructure that utilizes renewable energy should function efficiently, and ICT in tourism development must also be applied effectively to ensure that the sustainable value of Lake Batur reaches an acceptable level.

Implementing Scenario 1 and Scenario 2 for Lake Batur’s infrastructure involves several complex challenges. Technically, establishing and maintaining reliable real-time monitoring systems such as CCTV and water quality sensors requires advanced technology, stable internet, and skilled personnel, while integrating renewable energy adds further complexity for remote areas. Economically, substantial investment is needed not only for equipment and installation but also for ongoing maintenance and training. Social challenges include ensuring broad stakeholder access, digital literacy, and trust in these systems to encourage participation. Politically, effective governance, regulatory enforcement, and coordination among agencies are essential but can be hindered by bureaucracy and conflicting interests. Risks such as technical failures, cybersecurity threats, funding shortages, and stakeholder disengagement could undermine sustainability goals, highlighting the need for comprehensive planning, capacity building, and strong institutional commitment to fully realize the benefits of ICT and renewable energy in sustainable lake management.

4.3. Policy Implication

Effective implementation of Lake Batur’s sustainability management scenarios requires coordinated policy interventions across economic, environmental, socio-cultural, institutional, and technological dimensions. These policies must be supported by clear roles and responsibilities among key stakeholders to ensure cohesive governance and sustainable outcomes.

In the economic dimension, policies should aim to extend tourist stays and increase monthly visits by developing cultural arts attractions, enhancing accommodation quality, and offering integrated tour packages. Optimizing aquaculture practices and boosting fish production are also vital for local economic resilience. These initiatives necessitate active collaboration among the Bangli Regency Government, Provincial Tourism Office, Ministry of Tourism and Creative Economy, local communities, and private sector actors in tourism and fisheries.

For the environmental dimension, priorities include increasing forest and green open space coverage to exceed 50% of the watershed, reducing floating net cages (FNCs), and improving the lake’s trophic status through stricter land use enforcement, reforestation programs, and enhanced water quality monitoring. The Ministry of Environment and Forestry (KLHK), local environmental agencies, community organizations, and customary institutions are pivotal in driving these ecological restoration efforts.

In the socio-cultural dimension, reducing management conflicts, empowering lakeside villages, and strengthening local leadership through regular indigenous meetings, capacity-building, and environmental awareness campaigns are essential. Collaboration among customary institutions, local governments, NGOs, and academic bodies will foster community participation and preserve traditional knowledge in lake conservation.

Regarding institutional and management aspects, formulating and enforcing regional regulations (Perda) on lake use permits, construction, and FNC operations is critical. Establishing a multi-stakeholder lake management institution will facilitate coordinated conservation, permit issuance, and regulation enforcement. Leadership from the Bangli Regency Government, Provincial Government, Ministry of Home Affairs, Ministry of Public Works and Housing (PUPR), and local legislative bodies (DPRD), supported by legal and environmental experts, is necessary.

Finally, in the technology and infrastructure dimension, policies should promote integrated ICT systems for real-time lake monitoring, sediment trap installation, and renewable energy infrastructure development. These technologies are essential for advancing sustainability assessments and innovative management. The Ministry of PUPR, Ministry of Energy and Mineral Resources (ESDM), local ICT and infrastructure agencies, and technology providers, in partnership with research institutions, must collaborate on deployment and technical validation.

In summary, realizing Lake Batur’s sustainability scenarios depends on targeted, well-coordinated policy actions with clearly defined stakeholder roles at multiple governance levels. This integrated governance approach is crucial to sustainably balancing environmental preservation, economic growth, and social well-being. Continuous monitoring, adaptive management, and stakeholder engagement will be key to overcoming challenges and ensuring long-term success.

5. Conclusions

The Multi-Aspect Sustainability Analysis has demonstrated its utility as a robust decision-support tool for designing integrated Lake Batur management scenarios. By incorporating key performance indicators across five critical dimensions—environmental, socio-cultural, economic, institutional-management, and infrastructure-technology—MSA enables a comprehensive assessment of current sustainability status, identification of leverage factors, and simulation of the potential impact of policy interventions on the lake’s overall sustainability index. The sensitivity analysis within the MSA framework provides evidence-based guidance for prioritizing strategic actions, facilitating a transition from an alert to an acceptable sustainability status. As a systematic, data-driven, and stakeholder-inclusive approach, MSA strengthens adaptive and targeted decision-making processes in sustainable lake management.

While the MSA framework and its associated indexes have been robustly developed and validated within the specific context of Lake Batur, their broader applicability and potential for parameter refinement are important considerations. A promising avenue for future research involves applying these developed indexes to a wider spectrum of lakes, particularly those with varying management statuses, including unmanaged systems. Such comparative studies would provide invaluable insights into the adaptability of the parameters, enabling necessary adjustments and further enhancing the generalizability and utility of this comprehensive sustainability assessment framework for diverse lake ecosystems.

Without proper intervention, Lake Batur will experience severe environmental degradation. Water pollution will worsen, sedimentation will decrease the lake’s depth and capacity, and conflicts among tourism, fisheries, and agriculture will intensify. This decline threatens biodiversity and undermines the lake’s economic and sociocultural potential. Long-term mismanagement will harm local welfare and jeopardize Lake Batur’s status as a vital natural and cultural heritage site. Currently, the lake is categorized as being on alert for sustainability; without integrated improvement actions, it risks becoming critical and unsustainable.

Sustainable management of Lake Batur is a shared responsibility. Stakeholders should promptly follow up on restoration proposals to create a joint action plan incorporating environmental, sociocultural, economic, institutional management, and infrastructure-technology aspects. This will ensure the lake’s sustainability and long-term benefits for the ecosystem and community.

This research recommends directly measuring environmental indicators for Lake Batur and other lakes in Indonesia. It also suggests simulating dynamic changes using the “Systems Dynamics” method in future research.