Plitvice Lakes National Park

Since 2017, the State Party has been undertaking strengthened action towards regulating the construction of tourism facilities. The Public Institution Plitvice Lakes National Park (PIPLNP) has been participating in decision-making processes regarding issuance of construction permits, as per the provisions of the amendments to the Nature Protection Act (World Heritage Committee, 2018). The number of newly issued permits for construction has been significantly reduced. Permits for construction of houses exclusively used for tourism are no longer granted (UNESCO, 2018). Only occasionally the newly built family houses are used for rental purposes (State Party of Croatia, 2023). Adding to these strengthened measures, in 2018, the State authorities have initiated a process of amendments to the 2014 Spatial Plan of the area with special features for Plitvice Lakes National Park alongside the Strategic Environmental Assessment (SEA) that would elaborate the full extent of the potential cumulative impacts of the implementation of this plan on the property’s OUV and integrity (World Heritage Committee, 2018). This is carried out in compatibility with the Plitvice Lakes Management Plan 2019-2028 (new management zoning). So far, draft Strategic Impact Study for the Spatial Plan amendments has been completed, containing an overview of the existing state of space in relation to the drivers, burdens and environmental components, as well as an assessment of the impact on the OUV of the Park (State Party of Croatia, 2022). New Spatial Plan was supposed to be finalised by the end of 2024 (State Party of Croatia, 2023). However, there is no clarity when the SEA will be finalised. The State Inspectorate has been carrying out regular inspections for buildings, water and nature, with the plan to continue with regular inspections in the future (State Party of Croatia, 2019). In 2019, the nature protection inspection service organized 93 coordinated supervisions (State Party of Croatia, 2019). The water inspection service in particular checked the wastewater discharge from tourism facilities, raising awareness of the problem among owners, and resulting in installation of biotreatment units where collection pits were suspected to be defective (State Party of Croatia, 2019). The building inspectional service carried out monitoring controls in proceedings initiated during 2017 and 2018 in Plitvica Selo and Jezerce settlements, resulting with one decision for the removal of an illegally constructed building (State Party of Croatia, 2019). Overall, there has been a lot of positive development in addressing this threat in the past six years. Ensuring legal provisions for the implementation of the Management Plan through the amendments to the Spatial Plan will further secure protection of values of the site.

Quantity of water flow of the Plitvice Lakes system has been decreasing, as shown by hydrological analyses from 1952-1991 (Plitvice Lakes National Park Public Institution, 2019). However, it is difficult to separate the impact of potentially unsustainable water uptake from global climate changes (UNESCO and IUCN, 2017). Currently, Lake Kozjak, the largest and deepest lake in Plitvice (82ha, 47m deep) is the main source of drinking water for all facilities in the National Park and the municipalities of Rakovica and Plitvička jezera (Ministarstvo kulture Republike Hrvatske, 2007; Ministarstvo graditeljstva i prostornog uredjenja 2012; Vurnek et al., 2018). The water draw from Kozjak Lake does not seem to be excessive as in the short moment of the lowest water flow in the driest years, water draw is 5-6% of the flow or lower as the pump does not work on maximum capacity all the time (medium annual water draw from Kozjak is around 1.5%) (IUCN Consultation, 2024; State Party of Croatia, 2023). However, in the long-term, utilization of water from Kozjak Lake, especially during dry summer periods, could disrupt the natural processes of formation of tufa dams. Additional risks are posed by uncontrolled water extraction from the source of the Plitvica spring for the needs of Plitvica Selo and Poljanak settlements, while water supply installations also exist in Čujić Krčevina and Vrelo Koreničko (Plitvice Lakes National Park Public Institution, 2019). State Party of Croatia (2022) reported that a study “Conceptual solution for the Plitvice Lakes water supply system with the preparation of a mathematical model of the current and future situation and Pre- feasibility Study” has been finalised in 2019. The study analysed the complete water supply system and proposed guidelines for its future management and maintenance. The conceptual solution proposed two options for water supply outside of the Park boundaries, after which Lička Jasenica was selected as the future location (water supply system Lička Jasenica-Rakovica-Plitvice Lakes National Park) (State Party of Croatia, 2022). Concrete sub-option in that location will be selected during the preparation of project documentation, which was scheduled to begin in 2023 (State Party of Croatia, 2022). The progress is unknown and the State Party of Croatia (2023) reported that the time of construction of new water supply system has not been determined. Parallel to this process, intervention measures to reduce water losses from the Park were carried out in the period from 2018-2021, resulting with reduction of water losses by 30-40% (State Party of Croatia, 2022).

The current wastewater disposal seems to be satisfactory as almost the entire zone around the lake system, including the main tourist infrastructure, is connected to the sewage system where wastewater is treated in a plant (State Party of Croatia, 2022). Temporary solution with installation of a mobile wastewater plant in 2018 in Rastovača seems effective and helps mitigate the issue of water pollution when the plant is operational (State Party of Croatia, 2019). Društvo jedrskih strokovnjakov Slovenije (2022) reported the plant was out of function in 2022 for six months due to administratively caused delays in extending the contract with the wastewater treatment plant provider. The lease contract is now valid until 2026 (State Party of Croatia, 2022). The State authorities have been working on providing a permanent solution for wastewater treatment, by applying for a project with EU co-financing (the ‘agglomeration project’) (State Party of Croatia, 2019). The World Heritage Committee (2021) urged the State Party to accelerate the implementation of the project which was supposed to be finalised by 2023 (State Party of Croatia, 2019). However, the State Party of Croatia (2022) reported that the preparation of the project documentation will begin in 2023. In the meantime, the Institute of Public Health has been inspecting the plant every month to analyse the treated wastewater, and the results seem satisfactory, i.e., they meet the requirements of applicable legislation for underground discharges (State Party of Croatia, 2022; State Party of Croatia, 2019). Croatian Waters public institution and the Park have established regular monthly monitoring of water quality at 5 and 19 locations respectively (State Party of Croatia, 2022). The analyses provide a complete insight into basic physical, chemical parameters and bacteriological quality of the water. Responding to the World Heritage Committee (2021) decision, the State Party submitted water quality data. Results of the analysis for 2023 confirm good status of Plitvice’s waters (Nacionalni Park Plitvička jezera, 2024). Households in Plitvica Selo do not discharge wastewater directly into nature as they have their own biological treatment plants, whereas smaller settlements have collection pits (in accordance with the 2014 Spatial Plan-currently being amended) subject to supervision by inspectional service. During 2021 and 2022, 34 inspections were carried out, resulting with 18 decisions relating to the obligation to check through authorized persons whether collection pits are operating properly or the obligation to obtain water permits for the discharge of treated wastewater underground (State Party of Croatia (2022) noted these permits have been successfully obtained) and two offenses. The inspection activities have had an impact on the environmental awareness of residents.

Plitvice Lakes National Park is the most visited protected area of Croatia. It has experienced dramatic increase of visitors in the last 30 years, rising from 350,000 visitors in 1998 (WCMC, 2011) to 1.45 million in 2023 (Statista, 2024). In 2017, the record number of visitors was 1.7 million, with peak months being July and August with daily average of 10,000-12,000 visitors. In some days there were about 14,000 visitors (Plitvice Lakes National Park Public Institution, 2019; Vurnek et al., 2018). This surge in visitation has posed significant challenges to the Park’s fragile ecosystem, particularly in its lakes area where the concentration of visitors is the highest. In the last six years, the Park authority has been active in establishing new measures for visitor management, in line with its main objective not to undermine or threaten the values of the Park (Plitvice Lakes National Park Public Institution, 2019). New visitor management strategy was developed as part of the 2019–2028 Plitvice Lakes Management Plan. The strategy is based on the Recreation Opportunity Spectrum (ROS) methodology that takes into account the desired social, biophysical and management conditions at a destination and these have been determined in line with the new management zonation of the Park (Vurnek et al., 2019; Plitvice Lakes National Park Public Institution, 2019). Therefore, the strategy for managing the visitors in the defined classes I-V is consistent with the Park’s values. Some of the key measures in visitor management that the Park authority has been implementing include: limiting daily visitor numbers to 12,000, introducing online ticket booking with hourly entry limits of 650 visitors per each of the two entrances (1,300 visitors in total; temporal and spatial control), dynamic pricing to encourage afternoon visits, and introducing visitor monitoring system (Plitvice Lakes National Park Public Institution, 2019; State Party of Croatia, 2022). It seems the Park has been introducing necessary mitigation measures when needed as in 2022 and 2023 the limit to hourly visitor entrance was reduced to 600 and 500 visitors per entrance respectively (State Party of Croatia, 2022; State Party of Croatia, 2023). Current limit of visitors per hour has been calculated based on the average speed of visitors, defined visitor density along the trail of no more than one visitor per 3 m, and the fact that tour programmes from the two entrances partly use the same trails (Plitvice Lakes National Park Public Institution, 2019). The new visitor monitoring system provides insights into visitor movement in the Park, i.e., use of panoramic train or boat (State Party of Croatia, 2022). An important part of the visitor management measures is enhancing the safety of visitors and/or enabling dispersion of visitors in the Park. This is being tackled through investments in visitor infrastructure upgrades. Fences on trails have been installed for improved safety of visitors, a new viewpoint on the cascade system, Tomićevo pogledalo, has been constructed on a rarely visited path through the forest to enable dispersion of visitors, entrance 1 has been reconstructed, and the trail towards Veliki slap has been renovated (expanded to 2,6 m from 1,3 m) to mitigate crowding and enable better flow of visitors (IUCN Consultation, 2024; State Party of Croatia, 2022; Nacionalni Park Plitvička jezera 2024b; Nacionalni Park Plitvička jezera 2024c). All described measures respond to the World Heritage Committee (2021) decision noting that visitor management should be based on minimizing threats to the OUV, directly linking the carrying capacity with OUVs, visitor monitoring should be ongoing, and mitigation measures with caps on visitor numbers established as required. However, it is unclear whether the expansion of the trail to Veliki slap was justified by the set management provisions. The Management Plan notes that widening of trails is not possible as it would jeopardize the OUV of the property (Plitvice Lakes National Park Public Institution, 2019). Accordingly, it is advisable to monitor the sustainability of the determined limit to the number of visitors and adjust the limit instead of intervening in the Park measures that are not in accordance with the Management Plan.

Large carnivores are mainly threatened by roads that cross the Park, especially due to heavy traffic in summer months (Plitvice Lakes National Park Public Institution, 2019). Several cases of roadkill (1 lynx, 2 brown bears and 2 wolves) have been recorded in the last 20 years (Plitvice Lakes National Park Public Institution, 2019). Previously reported disturbance of bats in the caves (Ministarstvo kulture Republike Hrvatske, 2007) has been regulated by prohibiting access to the caves with nursing colonies throughout the year, except for monitoring purposes (IUCN Consultation, 2024; Plitvice Lakes National Park Public Institution, 2019).

Plitvice Lakes are exposed to a natural process of eutrophication, i.e. process of enrichment of water with nutrients. Under an anthropogenic influence, such as agricultural activity, animal husbandry, and wastewater discharge from tourism infrastructure and households, the process of eutrophication is likely to increase due to accumulation of nitrogen and phosphorus. Monthly analyses, performed by the Park since 2006, monitor basic physico-chemical and microbiological indicators in connection with tufa formation process, eutrophication and sanitary quality of water (Plitvice Lakes National Park Public Institution, 2019). Scientific studies concluded that in the period 2006-2020, there have generally been low nutrient concentrations, indicating that waters in the Park are oligotrophic (Brozinčević et al. 2023; Vurnek et al., 2020). Furthermore, detailed results of the analyses for each year are available at the Park’s website, and after 2020, the analyses have shown continued “good” or “high” water quality (Nacionalni Park Plitvička jezera, 2024). Such analyses are enabled by well equipped laboratory, investments into knowledge development of expert personnel and into new equipment. Additionally, some natural processes like leaching of soil/humus by terrestrial waters in the coast area of the lakes as well as input of organic material in lake waters by leaves of deciduous trees can increase the eutrophication in the lakes. One of the effects of eutrophication is overgrowing of edging zones and bottom of some of the lakes with macrophytes, often resulting in minimized circulation of water, building of the organic material, and slowing down of the tufa formation process. In some cases, eutrophication, with the weight of collected material, can endanger the barriers’ stability and even lead to disintegration of travertine dams (Ministarstvo kulture Republike Hrvatske, 2007).