Water protection

The water areas in Helsinki include extensive marine areas as well as the freshwater areas of the Vantaa River, various creeks, ditches, ponds and springs. In accordance with the City Strategy, the state of the small water bodies and coastal waters of Helsinki will be improved, and attention will be paid to the revival of the migratory fish stock. The significance of the sea will be strengthened and opening the nearby archipelago to public use will be continued. In addition to the environmental policy, water protection in Helsinki is regulated by the Small Water Bodies Programme, the Stormwater Management Programme, the Instructions on Prevention and Control of Floods, the Baltic Sea Action Plan, and the Water Resources Management and Sea Management Plans.

Sea water temperatures in Helsinki coastal waters break records

The temperature of sea water rose to a record-breaking level on the second week of July: the temperature of the surface waters in Kruunuvuorenselkä was as high as 25.2 degrees Celsius, and in the shallow waters close to the shore, the temperatures reached over 27 degrees in several spots. The record-breaking values were preceded by a marine heatwave of about a month. During a marine heatwave, sea water temperature exceeds the threshold value, calculated from the long-term seasonal monitoring data, for at least five consecutive days. The impact of marine heatwaves on the coastal marine ecosystem may be destructive as they may reduce the chances of survival for key species, such as the bladder wrack, in the coastal waters that are already under heavy stress.

Seawater temperatures were measured for a second consecutive year through a sensor network based on the IoT. An autonomous sensor network for observing the status of the environment will be developed further in the coming years. 

No major changes occurred regarding the eutrophication of the sea area. Total nitrogen concentrations were slightly lower than the long-term average, while the total phosphorus concentrations were slightly higher than the long-term average. However, the situation was somewhat better than the previous year as the nutrient concentrations at individual monitoring stations were slightly lower than the measurements from 2020. The amount of algae in seawater was higher than the long-term average, similarly to the past few years. However, compared to 2020, the situation had improved somewhat, as the amount of algae was lower in Töölönlahti, Seurasaarenselkä and the western outer archipelago, in particular.

The A-chlorophyll concentrations, which indicate the total levels of phosphorus and algae, have continued to grow, and the total nitrogen concentrations fluctuate around the long-term average. The increase in the turbidity of surface waters has stopped at the 2010 level, and the turbidity of the waters near the seabed has decreased. The oxygen level of water near the seabed is continuing to decrease in Helsinki coastal waters, partially due to the rising average temperature of the coastal waters. 

People at Eiranranta beach.
Image 10. The seawater temperature rose to a record-breaking level on the second week of July. Photograph by Julia Kivelä.

The Baltic Sea Challenge as support for marine conservation

Together with Turku, Helsinki is committed to implementing a third Baltic Sea Action Plan in 2019–2023. The action plan contains 117 water protection measures that take factors such as the EU Strategy for the Baltic Sea Region and the UN’s Sustainable Development Goals into account. The measures are divided between five objectives: 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 measures are divided extensively among the City divisions, in addition to which City of Helsinki construction services Stara, HSY and the Port of Helsinki are also involved. The progress on the measures is being monitored on a regular basis, and 93 measures had been started, were underway or had been completed in Helsinki by the end of 2021.

The measures that have progressed include many measures related to nutrient removal, the management of harmful substances, port operations and private boating, charting valuable sea areas, and international cooperation, in addition to the development of the activities of the local-level Baltic Sea panel, among other things.The cooperation with the University of Helsinki grew closer with the launch of a seminar series of urban environment and the extension of the professorship in the economics of Baltic Sea protection for 2021–2026. 

In the Baltic Sea Challenge, Helsinki and Turku also support other operators in implementing new water protection and Baltic Sea activities. In 2021, two new members joined the international partnership network of the Baltic Sea Challenge, and four partners updated their commitments.In February, a seminar titled ‘A clean, productive and shared Baltic Sea – regional and local actions for sustainable future’ was organised for the network members, and in November, an annual national seminar was held with the theme of littering and environmental education. Cooperation between cities around the Baltic Sea region to protect the Baltic Sea was developed together with the Swedish organisation Race for the Baltic.

In the summer, a communication campaign aimed at leisure boaters regarding toxic paint and underwater noise was implemented, and we also participated in the ‘Mahanpuruja muovista’ (‘tummy ache from plastic’) campaign of the Keep the Archipelago Tidy Association and the Helsinki Region Environmental Services Authority (HSY). The Baltic Sea Challenge participated in the Baltic Sea Day on 26 August 2021 by organising a webinar where City employees learned about different perspectives related to their work in terms of sea protection.

The projects in the water protection enhancement programme improve the state of Helsinki’s small water bodies

Helsinki is involved in two projects launched by the Ministry of the Environment and included in the Water Protection Enhancement Programme. The shared goal of the projects is to improve the state of small water bodies and sensitive bays in Helsinki.

In the HuLaKaS project on stormwater quality and inlet-specific filtering is charting the risk areas and functions that will reduce the quality of stormwater in Helsinki and the location of such risk areas regarding sensitive bodies of water. The project will result in a map of risk areas to be used for the City’s planning and environmental protection efforts. To improve the stormwater quality in the risk areas, the project will pilot the functionality, usability and cost-efficiency of a filter to be placed into stormwater inlets. To summarise the project, an assessment of the filtering method’s functionality at the level of each catchment area and its replicability and scalability for different risk areas in cities will be produced through modelling.

The ‘Tools for Improving Construction Site Water Quality’ project aims to reduce the amount of solids and harmful substances from construction and demolition sites ending up in waters. The project will collect information about the environmental load caused by construction sites and assess its significance for the creeks in the city and the Baltic Sea. Through pilot worksites, information on the level and quality of environmental load and best practices for controlling the load in worksite conditions will be collected. The project aims to update Helsinki’s instructions on worksite water and study which threshold values could be reasonably included in various instructions on the topic. The intention is to study the process of worksite water management from planning to implementation and control and, based on the results achieved, develop an operating model that can be scaled for cities of various sizes. With the model, the quality control of worksite water can be integrated into the normal construction process in cities. 

Occurrence of PFAS studied in Vantaa River

Over a million people live in the impact area of the Vantaa River, and the river meanders for over 100 kilometres from Riihimäki to the bay in Vanhakaupunki, Helsinki.The Vantaa River is the auxiliary raw water source for the Helsinki Metropolitan Area. The load on the Vantaa River has decreased, and the ecological condition of the river is classified as satisfactory overall. The Kytäjoki river area and the upper reaches of the Kerava River are in ecologically good condition. A good ecological condition would also be achievable in the lower reaches 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 wastewater and agriculture. 

In 2020–2021, the catchment area of Vantaa River was involved in the PFAS project that monitored the occurrence of harmful perfluorooctanesulphonic (PFOS) and per- and polyfluoroalkyl (PFAS) compounds. PFAS are used in various consumer products, electronics and fire retardants. PFAS were detected in all samples studied during the project. It was concluded that wastewater treatment plants and runoff waters were the greatest sources of PFAS to Vantaa River. Of the PFAS compounds, the accumulation of PFOS into fish exceeded the environmental quality norm or was close to exceeding it in Vantaa River and downstream of Kerava River. Downstream of Vantaa River, the norm was exceeded multifold. Further research into the concentrations in the fish from the water area are required to determine if the use of the fish for food should be restricted. More in-depth research on the stormwater volume and quality is also required. 

The survey on the blue network complements the overview of ecological networks

The Urban Nature themed map on Helsinki’s city plan illustrates the City’s ecological networks, forest network, meadow network and blue network. In the survey on the blue network, the information on water ecology will be elaborated on and offered in a more accessible format. The information on the blue network survey on the natural state of small waters, shores and the sea area make it easier to take natural values into account when planning land use, monitoring waters and otherwise developing the areas. 

In the preliminary survey carried out in 2021, a method was defined classifying the quality and structure of a network based on location data. The accuracy of the location data analysis was improved through land surveys. The survey will be completed in 2022.

Wastewater was treated efficiently

The amount of water pumped into the water supply network in 2021 was 94 million cubic metres in the Helsinki Region Environmental Services Authority’s (HSY) water supply area, while 52 million cubic metres were pumped into the Helsinki network.

The Viikinmäki Wastewater Treatment Plant in Helsinki is the largest water treatment plant in all of Finland and the Nordic region. The Viikinmäki plant, built within the bedrock, processes the wastewater of about 890,000 residents, not only from Helsinki, but also Central and Eastern Vantaa, Kerava, Tuusula, Järvenpää, and Sipoo.

The plant treated a total of 140 million cubic metres of wastewater, 73 million cubic metres of which came from Helsinki. The total volume of wastewater was slightly higher than in the previous year, while the volume of wastewater from Helsinki decreased somewhat from the previous year. The Viikinmäki Wastewater Treatment Plant met all the environmental permit regulations. Combined sewer network overflows amounted to 0.15% of the overall amount of wastewater.

The 2021 treatment efficiency for phosphorus in Viikinmäki was 97%. For biological oxygen demand, the removal efficiency was 98%, and for nitrogen, 91%. The wastewater treated at the Viikinmäki treatment plant is conducted through 16-kilometre-long tunnels to the open sea.

The phosphorus load from the Viikinmäki Wastewater Treatment Plant on the sea areas in front of Helsinki was 18 tonnes (-14% from the 2020 level), and the nitrogen load was 470 tonnes (-2% from the 2020 level). For eutrophication, the nitrogen load is more significant because nitrogen is a minimum nutrient in the waterways in the Helsinki region.

Image 11. The nitrogen and phosphorus load caused by the Viikinmäki Wastewater Treatment Plant on the Baltic Sea in 2008–2021.

Water protection control focused on the tasks defined in the Water Services Act

During the year, different courts issued several decisions regarding the application of the Water Services Act on applications for an exemption from the connecting obligation. Supervision resources also had to be focused on the tasks defined in the Water Services Act when the stormwater pipeline renovations made by the HSY brought on an influx of applications from persons who wished to be exempted from the connecting obligation. This workload reduced other work done on water protection control. Due to the busy year, it was not possible to carry out all inspections detailed in the control plan. Because of task prioritisation, the number of inspections related to hazard reports was much lower than previously.

The environmental hazards caused to creeks from the drilling of geothermal wells have kept the environmental supervision authorities busy for several of the last few years. The challenge was met by preparing joint instructions for the treatment of water generated from geothermal drilling with HSY and the municipalities in the Helsinki Metropolitan Area. Drilling entrepreneurs were also heard during the preparation of the instructions.The instructions were published in February 2021. The deployment of the instructions will take time and will need to focus on in the future since geothermal systems are increasingly popular.

Eyes on the future

The close proximity of the sea is a very important success factor for Helsinki and a part of local identity. Most of the city area is sea, and there are 300 islands in this area. The state of the marine environment must be taken into account in our operations as a source of competitiveness and well-being for the city, its residents and organisations.

Helsinki will do its part to protect the Baltic Sea. The sea is being threatened by eutrophication, hazardous substances and littering, which have severe consequences for marine nature and biodiversity.

The eutrophication of the sea areas in Helsinki is caused by the nutrient load from the catchment area and the special characteristics of coastal waters and bays. Despite the decreased nutrient load, the phosphorus concentration in the middle and outer archipelagos has grown since the start of the 21st century. To control eutrophication, it remains important to reduce the nutrient load and opt for alternative methods of retaining nutrients in soil and recycling them. 

Hazardous substances and littering are a threat to the ecosystem and habitats in the Baltic Sea. Hazardous substances and litter are carried from land to sea in wastewater and stormwater, wind and currents. When these materials end up in the environment, they pose a danger and cause harm to both humans and biota and reduce the recreational value of coastal and maritime areas. We can intervene in the problem and develop new solutions by raising awareness of the sources and routes of hazardous substances and litter. The environmental supervision authorities’ focus on the instructions and supervision on processing worksite water will help to improve the condition of waterways. 

To reduce the load on the sea area, the Metropolitan Area must implement targeted actions in the local catchment areas. Monitoring the impact of the measures is especially important in urbanised areas with fragmented land use. Helsinki will make the monitoring of currents and coastal waters more effective in the coming years by using IoT technology. Current channels and coastal waters will have several continuously running monitoring stations that will serve to verify and enhance the investments made in improving the condition of the environment.