The EH-REK project: ”Ecohydrological rehabilitation of recreational reservoirs in Arturówek" (Łódź) as a model approach to the rehabilitation of urban reservoirs” (LIFE08 ENV/PL/000517) financed by the LIFE+ program was carried out in Łódź in Arturówek in 2010-2015.

On 24 May 2018, during the EU Green Week – Europe’s biggest environmental event – Commissioner Karmenu Vella announced the winners of the 2016 and 2017 LIFE Awards. From 62 finalists, EH-REK project have been awarded the title “Best LIFE project”. The LIFE Awards recognise the most innovative, inspirational and effective LIFE projects in the fields of nature protection, environment and climate action. If applied widely, they can have a highly positive impact on the environment, boosting economic growth and providing significant benefits for European citizens. 


Fot. 1. Representatives of the EH-REK project – Prof. dr hab. Maciej Zalewski and Dr. Tomasz Jurczak receive from the hands of Karmenu Vella – Commissioner of the EU, the prestigious "Best of the best" award (  

The reservoirs in Arturówek are one of the most important recreation areas for the inhabitants of Łódź. Like most waters in urbanised areas, they are significantly influenced by the anthropogenic impacts negatively affecting the quality of water, thus limiting the usefulness of this area. The actions taken in the past to improve this state did not bring the expected results. Therefore, it was necessary to take measures limiting the inflow of pollutants to these reservoirs, which would allow for their recreational use. 

The project proposed an innovative approach in terms of: 1) consolidating knowledge concerning the functioning of the urban water ecosystems, 2) methods of planning and decision-making in the management of water ecosystems in the urban areas, 3) developing and applying ecohydrological technologies and their synergy in order to accomplish the objectives prescribed in the EU directives (Directive No. 2006/7/EC concerning the management of bathing water quality and Water Framework Directive No. 2000/60/EC) and 4) a training system, know-how dissemination and cooperation based on joint actions undertaken under the platform of the stakeholders. These activities were to contribute to the improvement of the water quality in the recreational reservoirs located in Łódź in Arturówek and to reduce the problem of the annually occurring cyanobaterial blooms in the reservoirs. 

The project was divided into five stages. First, in 2010-2011 an identification of the pollution sources as a threat and an opportunity analysis were done, as well as to assess the balance of pollutants flowing in and out of the reservoirs in Arturówek. Second, on their basis, a mathematical model was developed, which was used for the concept of a reservoir restoration in 2012, according to which technical projects were carried out, appropriate arrangements were made and the required permits were obtained. Third, the collected documentation enabled the implementation of the investment works ongoing in the period from January to June 2013. Investment works aimed at improving the quality of the Bzury river and eliminating the cyanobacteria bloom occurrence in the reservoirs in "Arturówek" included restoration activities mainly related to the bottom sediments removal from the three recreational reservoirs: Lower Arturówek (AD), Middle Arturówek (AŚ) and Upper Arturówek (AG) and two from 17 small retention reservoirs (Bzura-7 and Bzura-17), water exchange and biomanipulation. In addition, innovative systems have been constructed to reduce the inflow of pollutants to reservoirs from urban areas from the river and stormwater drainage systems. In turn, the optimisation of their operation carried out in 2014, as the fourth stage of the project, increased the efficiency of the water treatment. The implemented investments were aimed at restoring the original state to degraded the aquatic ecosystems and limiting the inflow of pollutants in the future. The final element of the project was the implementation of training for children, students, teachers and trainers as well as local governments, decision makers and institutions controlling the water status based on the solutions applied in the project. 

The innovative of the solutions proposed within the EH-REK project is connected with the application of technologies combine the biological, hydrological and water engineering knowledge (Jurczak et al 2018a). The essence of these innovative methods is the use of ecosystem properties as a tool to improve the water ecosystems and to build sustainable development. Such solutions are called ecohydrology (Zalewski 2000, Zalewski 2015). According to this concept, the hydrotechnical infrastructure allows for the control of hydrological parameters of the river or reservoir, controlling the quality of their water. In turn, modifying biological elements in the system allows us to change – and thus to manage – the water cycle. Such an approach is not widely applied in urban areas, where traditionally only engineering solutions are used, under which the control of possibilities of the natural cycles are strongly limited due to the huge human impact on the environment. 

Fig. 1. The sequential sediment-biofiltration system (SSBS) constructed at the place of the Bzura river inflow to the Bzura-7 (A), Bzura-17 (B) reservoirs and the Upper Arturówek reservoir (C) (photo: T. Jurczak) and the prototype of this system installed on the left bank of the Sokołówka River to retain and treat stormwater (D) (photo: S. Szklarek). 


The integration of hydrological and biological methods can effectively limit the inflow of pollutants to water reservoirs and reduce the problem of the toxic cyanobaterial blooms in reservoirs. An example of such a combination are the sequential sedimentation-biofiltration systems (SSBS) constructed in Upper Arturówek reservoir as well as in the Bzura-7 and Bzura-17 reservoirs (Fig. 1). The prototype of this system was implemented under the framework of the SWITCH project in 2006-2011 in Łódź on the Sokołówce River (Szklarek et al. 2018). 

The SSBS applied in Arturówek, and located in the upper reservoir at the river inflow site, is an approach that uses the sequential process of water treatment (a sedimentation zone, a pollutant adsorption zone in the geochemical structures and a zone for the assimilation of the pollutants in plant structures) and does not require additional areas. Its efficiency can be improved by using structures supporting the sedimentation process and decreasing the stormwater inflow. Proper management of these zones, including regular monitoring and a removal of excess sediments, will ensure a high efficiency of the system and will extend the system's operating time. The effectiveness of such a system in the removal of pollutants was estimated on the basis of monitoring studies conducted in 2014 in the Upper Arturówek reservoir (Fig. 1c), where a reduction of the total suspended solids supplied to the reservoir by river was achieved by 90%. At the same time, a 57% reduction of the total nitrogen and phosphorus was achieved, and the ion forms of these nutrients (NO3-, NO2-, PO43-, NH4+) from 49 to 91.3% (Jurczak et al. 2019b). The implemented system can be modified depending on the size and type of the pollutant input as well as the morphology and hydrological characteristics of the reservoir. 

Such systems can be additionally equipped with underground separators and sedimentation tanks responsible for the pretreatment of stormwaters with the sediments discharged from streets and parking places (e.g. oils or fuels from motor vehicles). Such enriched systems (Fig. 2), called hybrid systems, are characterised by a higher efficiency in removing suspended matter (up to 98.6%) and nutrients from 40% to 97.5% (Jurczak et al. 2019b; Jurczak et al 2018a).  

This kind of system, due to the underground location of the technical elements, are not visible and do not damage the landscape. An example of such a system was implemented below Wycieczkowa street in Łódź for the retention and treatment of the rainwater previously discharged from the street, pavement and parking places directly into the river. In addition, the specific construction of the weir (board with a slot in its lower part) applied in this hybrid system, improves the retention capacity of the reservoir to collect the stormwater and keeping a constant flow to the river below the system. It mitigates intense river flow during rainfall, thereby increasing the sedimentation of the suspended matter transported with stormwater, contributing to their pre-treatment. The conducted research has shown that the hybrid system used for the purification and retention of the stormwater supplied from Wycieczkowa Street to the Bzura River effectively reduces flood waves for rainfall not exceeding 9 mm (Jurczak et al 2018a). This limitation is caused only by the limited size of the demonstration system, which does not allow for complete water retention at higher precipitation.  

In turn, the use of aquatic vegetation in the SSBSs and hybrid systems reduce the nutrient concentrations in the reservoirs and also has a positive impact on the other aspects of the water ecosystems such as: habitat sites (hiding places, feeding and breeding sites) for various bird species, fish and invertebrates, including those improving the quality of water in zooplankton reservoirs, increasing biodiversity in the reservoir and its surroundings, and improving the aesthetics of the reservoirs as recreation areas. 

Fig. 2. The hybrid system constructed in Łódź to retain and purify stormwater supplying from Wycieczkowa street (photo: T. Jurczak). 

Fig. 3. The scheme of a hybrid system for purification of stormwater transported from impermeable areas to the Middle Arturówek reservoir (photo: T. Jurczak, scheme: M. Łapińska). 


In the middle of 2013, the reservoirs in Arturówek were opened for recreational use. In the 2014-2015 the optimisation works of the systems were carried out and a monitoring program was applied to estimate of the efficiency of the systems in nutrients removal. The high water quality in all restored reservoirs (Jurczak et al. 2019b) confirms the effectiveness of the implemented actions. 

These ecohydrological solutions implemented in Łódź as part of the EH-REK project have had a positive impact on improving the water balance by the water retention in the landscape and reducing flood wave in rivers, as a consequence the excessive outflow of stormwater from the urban impermeable areas. Water retention in the landscape improves thermal conditions in cities and increases humidity, which indirectly affects the health of its inhabitants, contributing to the reduction of asthmatic diseases and allergies (Kupryś-Lipińska et al. 2009). Moreover, the reduction of flood wave in rivers reduce the negative consequences of intensive rainfall as: a flooded streets, viaducts or buildings, which has a positive impact on the economy of cities. 

Fig. 4. The inflow of stormwater to the Lower Arturówek reservoir before investment efforts (A) and after the construction of the hybrid system (B). The inflow of the Bzura River to the Upper Arturówek reservoir, before investment activities (C) and after the SSBS construction (D). The impact of restoration and protection efforts on the water quality in Arturówek reservoirs (E and F) (photo: T. Jurczak). 

The solutions proposed in the project and approach to water management improve the quality of the water in the recreational reservoirs in Arturówek in Łódź and increased their landscape value, contributing to the increase of biological biodiversity (Jurczak et al. 2019b). It was estimated that the cost of construction of sequential sedimentation-biofiltration systems and hybrid systems reducing suspended solids and nutrient loads inflowing to the reservoirs were lower than that of sediment removal (Jurczak et al. 2019b). Removal of sediments is expensive and often has a short-term effect, especially in urban areas. It is assumed, that the SSBS and hybrid systems have long-term actions, protecting reservoirs against the inflow of pollutants, with much lower investment and maintanence costs. However, in order to determine their long-term impact on water quality and the real costs of managing such systems in the near future at least 10 years, compared to traditional reservoir maintenance (Jurczak et al. 2019b), further monitoring of the applied solutions is needed. 

The knowledge and experience gained in the implemented project were used to develop the concept of restoration for other urban recreational reservoirs in Łódź city, which are elements of the blue-green network of city. A detailed concept includes the Stawy Jan and Stawy Stefański reservoirs, which are a place of rest and physical activity for many inhabitants of Łódź, like the reservoirs in Arturówek. Their relatively small capacity, as well as the significant inflow of nutrients from the basin favor the formation of cyanobacterial blooms, which have been observed in these reservoirs from many years. The concept developed in 2014 was consulted and accepted by the city authorities and is now being gradually implemented in these reservoirs.

Obtained results were used to submit three patent applications. The research and implementation works carried out in Łódź were presented at numerous international conferences, including ECOSUMMIT2016 and SEFS2017 as well as being presented in the manual untitled: "Water in the City" as demonstration and innovative systems, for cleaning and retaining stormwater and also as a part of the Nature-Based Solution approach. The solutions implemented in the EH-REK project were awarded the "Best of the best" prize by the European Union among all LIFE projects ended in 2016 and 2017. 

The ecohydrological approach to the restoration of urban recreational reservoirs presented in Arturówek can be now used as a model system for the management of water ecosystems in other cities. An example of such activities, taking into account the harmonisation of hydrotechnical solutions (stormwater retention and its pretreatment) and ecological biotechnologies are currently being implemented as innovative projects by the municipalities in the cities of Konstantynów Łódzki, Zgierz and Łask. These projects are being implemented based on the knowledge and experience developed in the EH-REK project in Łódź from 2010-2015. 

In addition, the SSBS and hybrid systems such as ecological biotechnologies solutions can be successfully used as elements of a blue-green infrastructure for adaptation of cities to climate change (Zalewski et al., 2012). An example of such activities is the project LIFE14 CCA/PL/000101 "Adaptation to climate change through sustainable management of water of the urban area in Radom City", using the approach to water management in the city presented in the approach. This project was selected in 2015 as the one Polish project in the LIFE Program 'Adaptations to Climate Change' competition and directed to get financing. This project will allow for the implementation of systems tested in Łódź as elements of the city of Radom contributing to its adaptation to climate change.