In accordance with the City Strategy, the state of the small water bodies and coastal waters of Helsinki will be improved and the revival of the migratory fish stock will be paid attention to. The significance of the sea will be strengthened and opening the nearby archipelago to public use will be continued.
The water areas in Helsinki include extensive marine areas, as well as the freshwater areas of the Vantaa River, various streams, ditches, ponds and springs. The water quality of the City is affected by the impurities in storm water, nutrients brought by scattered loading, cleaned sewage led to the outer archipelago, human activities, the muddy waters flowing from the Vantaa River, and the state of the Gulf of Finland. In addition to the environmental policy, water protection in Helsinki is regulated by the Small Water Bodies Programme, the Storm Water Strategy, the flooding instructions and the Action Plan for the Baltic Sea Challenge.
Cities’ small water bodies are important habitats and migratory routes for various organisms, and they have recreational value for residents. The ecological, recreational and scenic value of small water bodies has increased significantly in recent years, and taking small water bodies into account in urban planning and ecology is important. The water quality of creeks and ponds is monitored with annual sampling.
A large area of impermeable surface in the catchment area, great fluctuations in the water flow, occasional large amounts of solids in the creek water, hygiene problems, stream bed displacements and modifications, and a decrease in the natural vegetation of the shore are characteristic of creeks in Helsinki.
In 2019, a quality survey regarding the quality of storm water directed into creeks was started with continuous measurements and by analysing the waste material accumulating in storm water wells.
The two-year Urban Waters project was completed in 2019. The objective of the project was to improve the water quality of local water bodies by purifying cities’ storm waters. The project involved building two biochar-based storm water filtration structures in locations in Helsinki and Espoo in which storm waters had been observed to load nearby water bodies. The objective was to test biochar as a filtration material and obtain construction and usage experiences with biochar solutions. Another goal was to produce structures that purify storm waters and are suitable for a dense urban environment and viable for implementation in other urban locations as well.
In Helsinki, the biochar filtration area was implemented as a shallow filtration basin in a side stream of the Maunulanpuro creek in Metsälä. Because of small industry, this side stream is especially susceptible to harmful substance leaks and oil spills, for example. The last significant oil spill occurred in the autumn of 2016. Oil and other harmful substance leaks endanger the naturally procreating population of Atlantic salmon in Maunulanpuro.
After the filtration basin was completed, its operation and purifying effect on storm water was monitored by taking water samples before and after the carbon filtration. The filtration was discovered to efficiently remove phosphorus from storm waters, but in terms of nitrogen, the benefits were less significant. Various harmful substances occurring in cities’ storm waters, such as heavy metals, oil hydrocarbons and polyaromatic hydrocarbons, were also efficiently caught in the filtration process. A significant portion of the removal of harmful substances was due to the elimination of solids. The monitoring of the operation of the filtration basin will be continued in the spring of 2020 with funding from the Ministry of the Environment.
Over a million people live in the impact area of the Vantaa River, and the river winds for over 100 kilometers from Riihimäki to the bay in Vanhakaupunki. The river is a valuable and attractive fishing location where Atlantic salmon and Brown trout travel up to spawn. The load on the Vantaa River has decreased, and the ecological condition of the river is classified as satisfactory. The Kytäjoki river area and the upper reaches of the Kerava River are in ecologically good condition. A good condition would be achievable in the lower reaches as well if the annual median of the overall phosphorus concentration were to reach a level of 60 µg/l. Phosphorus and nitrogen enter the Vantaa River from sewage and agriculture.
In connection with the Pienet AVL 20-99 puhdistamot (‘Small AVL 20-99 treatment plants’) project of the Water Protection Association of the River Vantaa and Helsinki Region, visits were made to five properties located in Helsinki. When operating inadequately, property-specific treatment plants may pose a considerable loading risk to the environment. Sewage systems falling between those of detached houses and treatment plants requiring an environmental permit in terms of their load are used in locations such as campgrounds and course centres or business premises located outside sewer systems. The advisory visits involved surveying the functionality of the properties’ sewage systems and providing the treatment plant technicians with advice on maintaining the systems. The visits resulted in the creation of a guide that provides procedure recommendations to treatment plants and municipalities responsible for supervision in the area. Shortcomings, the remedying of which requires follow-up monitoring, were observed in the majority of the locations in Helsinki.
The condition of Helsinki’s marine areas is being monitored in accordance with an extensive joint monitoring programme. Changes in the quality of sea water have been relatively moderate in recent years, and the condition of the fauna of the seabed has remained relatively unchanged in the 2010s. A reduced external nutrient load keeps the overall condition of Helsinki’s marine areas relatively stable. The ecological condition of Helsinki’s marine areas varies from passable to satisfactory when moving from the coast towards the open sea. However, individual events, such as the operational failure of the Suomenoja treatment plant in the summer of 2019, continue to have local adverse effects on the water quality.
The blue-green algae blooms occurring in 2019 were not as extensive and long-lasting as those in 2018. In the wake of 2018, a service called Levämittari (hel.fi/merivesi), which indicates the amount of algae and blue-green algae floating in the water on a scale of 0–100, was released for the residents of the municipality. The value of the indicator is updated daily in the swimming season, providing valuable information to residents in the marine areas.
In 2019, the condition of the underwater vegetation by the coast was surveyed more extensively. Surveying the condition of the underwater vegetation supports the implementation of the City’s Maritime Strategy by surveying the occurrence of valuable underwater nature sites. In the 2010s, the condition of the underwater vegetation in Helsinki’s marine areas has been stable, but relatively poor. For example, occurrences of the key species bladder wrack are in poor condition and fewer than in the previous decades. Closer to the coast, intensive construction in shore areas and the use of the marine areas keep the seabed silted, and the water has grown cloudier in recent years, which has an adverse effect on the condition of the underwater vegetation.
In 2019, 96 million m3 of water was pumped into the water supply network of the HSY water supply area, while 42 million m3 was pumped into the Helsinki network. The water consumption per capita in Helsinki was 180 litres per day, which was the same as in 2018.
A total of 107 million m3 of sewage was delivered to the Viikinmäki sewage treatment plant for treatment, of which 78 million m3 came from Helsinki. The amount of sewage was greater than in the previous year. The Viikinmäki sewage treatment plant met all the environmental permit regulations. Combined sewer network overflows amounted to 0.19% of the overall amount of sewage.
Load to the Sea
Nitrogen and phosphorus load channeled to the sea from the Viikinmäki treatment plant, tons per year
The 2019 treatment efficiency for phosphorus in Viikinmäki was 97%. For biological oxygen demand, the removal efficiency was 97%, and for nitrogen, 90%. The sewage treated at the Viikinmäki treatment plant is conducted through rock tunnels to the open sea, about eight kilometres away from the shore. The phosphorus load from the Viikinmäki sewage treatment plant on the sea areas in front of Helsinki was 20 tonnes (+33% from the 2018 level), and the nitrogen load was 530 tonnes (+17% from the 2018 level). For eutrophication, the nitrogen load is more significant, because nitrogen is a minimum nutrient in the waterways in the Helsinki region.
Work related to litter accumulating on beaches was continued by the City in co-operation with the Finnish Environment Institute and the Keep the Archipelago Tidy Association. Site formation, dredging and shoreline construction increase litter. In 2019, litter caused by fill worksites was controlled better than before. The sea fill projects on Koirasaari in Kruunuvuorenranta and Ahdinallas in Jätkäsaari were carried out in an area limited with a protective curtain. There were no other sea fill work sites in 2019.
The winners of Helsinki’s snow handling innovation contest were chosen in 2019. The City will continue trying out and developing solutions with four businesses that fared well in the contest. Different alternatives will also developed for snow handling, such as new piling sites and snow melting alternatives, in co-operation with the City’s other operators. The Ministry of the Environment will publish its report on dumping snow into the sea in 2020.
Together with Turku, Helsinki is committed to implementing a third Baltic Sea Action Plan in 2019–2023. The Baltic Sea Action Plan contains 117 water protection procedures that take factors such as the EU’s Baltic Sea strategy and the UN’s objectives on sustainable development into account. The procedures are divided between five objectives, which are clear coastal waters, a healthy marine habitat, clean and safe water transport, systematic use of water areas and active participation by the residents in the Baltic Sea region. The procedures are distributed extensively among the City’s different divisions, but in addition to them, Stara, HSY and the Port of Helsinki are also involved. The implementation of the procedures is monitored on a regular basis, and the aim is to improve resourcing by means such as creating projects.
In 2019, the Baltic Sea challenge network was joined by ten new members, including the municipality of Sipoo. A national Baltic Sea challenge seminar was held for the network members in November. In addition to this, the Baltic Sea challenge organisation organises various events in co-operation with the network members on a regular basis. For example, a climate camp event open for everyone was held during the Helsinki Design Week event. The activities of the Baltic Sea challenge have also been presented at international and local events.
The objective of the international BEST – Better Efficiency for Industrial Sewage Treatment project coordinated by Helsinki is to improve co-operation between industrial businesses, sewage treatment plants and environmental authorities and develop industrial sewage processing solutions in the Baltic Sea region. The duration of the project will be from October 2017 to September 2020.
In 2019, the project involved a Baltic Sea-wide survey on the current state of industrial sewage treatment. The survey focused in particular on industrial plants that direct their sewage to municipal sewage treatment plants. Legislation, regulations and official supervision that bind industrial plants were compared in different countries, and efforts were made to chart the differences between countries and bring up both good practices and bottlenecks.
Recommendations concerning the management of industrial sewage directed to municipal sewage treatment plants covering the entire Baltic Sea region are also being prepared. The goal of the recommendations is to provide unified guidelines for good practices not only in the Baltic Sea region, but nationally to individual countries as well.
Helsinki continued as a partner in the BSR WATER project started in 2018. The project compiles completed and still running flagship projects of the EU’s Baltic Sea strategy, the goal being to take forward and refine the results of the projects. In 2019, Helsinki took part in particular in the storm water work of the project. The project involves surveying the current state of storm water management and creating policy recommendations for storm water management. Helsinki collected information on local storm water management from cities, compiled an account of Finnish legislation concerning storm water and took part in the work to update HELCOM’s storm water recommendations. In addition to the storm water recommendations, the project involves collecting materials for recommendations concerning the recycling of phosphorus and harmful substances. Helsinki’s case examples of natural storm water quality management were shared in the Baltic Smart Water Hub online portal maintained in the project.
Eyes on the future:
In 2020, the City of Helsinki will continue charting valuable underwater nature sites together with the Finnish Environment Institute and Metsähallitus. Even though the underwater nature of Helsinki’s marine areas is in poor condition in some places, there are also beautiful and valuable sites in the areas. Highlighting their existence is important to preserve underwater nature. The protection of valuable marine nature sites should be taken into consideration when planning the use of the areas.
In the coming years, it will also be important to survey occurrences of valuable underwater nature types in the waters and acquire deeper knowledge of species occurring in small water bodies. This will facilitate creating appropriate protection and restoration procedures and maintaining biodiversity.