Review of the state of the Tallinn Bay and the factors affecting it
(presented on the seminar "From planning to concrete art: Action plans by Baltic Sea Challenge cities" on June 7, 2011 in Jurmala, Latvia)
The coastal waters of the city of Tallinn cover the area between the Kakumäe and Viimsi peninsulas. There are three distinct bay areas: Tallinn Bay, Paljassaare Bay and Kopli Bay. The shore waters are shallow but deep rapidly. Tallinn Bay has a steep slope, which allows for good water exchange with the waters of the Gulf of Finland.
There are two islands, Aegna and Naissaar, and two bigger lakes: Harku (160 ha) and Ülemiste (992 ha), the latter of which is the main raw water source.
The Old Town is situated close to the sheltered Tallinn bay, which is a natural harbour and the main passenger port. The harbor in Kopli Bay serves mainly for cargo traffic. There are three public beaches: Pirita, Stroomi and Kakumäe on the coastline.
In 2009 was made the study of the status of ecological condition of the coastal waters of the city of Tallinn. Five water bodies connected with Tallinn coastal area were evaluated in current study. The monitoring work was held in Tallinn Bay, the Pirita river estuary and Kopli Bay. The monitoring strategy was based on the requirements of the EU WFD and the aim of the strategy is to survey the ecological quality of coastal waters. During this monitoring activity data was collected and the status of Tallinn and Kopli coastal water bodies is classified according to the established national classification scheme.
The classification scheme is based on the biological elements. Those are phytoplankton (chlorophyll a), phytobenthos and macrozoobenthos. Physical quality element as water transparency is used as supportive parameter in this work.
In result of that study the classification scheme showed that in three of five investigated water bodies (Miiduranna, Paljassaare, Pirita) the ecological status was classified as ―/moderate/. Two of five water bodies were classified as ―/bad/ (Kalaranna-Russalka and Stroomi). Long-term improvement trends were observed in Paljassaare and Miiduranna sea areas. Negative dynamics were observed in Kalaranna-Russalka and Stroomi areas.
According to the study, the most significant physical factor is decreasing oxygen concentration, which causes anoxia and promotes eutrophication
The inflow of storm water, waste treatment plant water, wastewater from shipping, Pirita river waters and dust-rich air have certain impact on the water transparency and on the oxygen content- nutrients and floating substances witch are causing phytoplankton are discharged into the sea.
The large-scale nutrient over-enrichment is one of the most serious threats against the health and future perspectives of the whole Baltic Sea ecosystem.
Actions by the city of Tallinn
1. Preparing of storm water handling strategy where are clarified following activities
1.1 Reducing the pollution load of the storm water released into the sea.
- Implementation of street cleaning methods that improve storm water quality- cleaning up streets with dry method (Keeping sidewalks, roads, parking lots etc clean can help keep our waterways clean too. When it rains, trash, dirt, and chemicals that have built up on these surface can run into the street and eventually the storm drain. Sweeping up these areas instead of hosing them down and put dirt and trash into the garbage, instead of into the storm drain.)
1.2 Minimizing oil and oil products in storm water.
- Installation of oil filters on storm water drainage systems of major roads and parking lots.
1.3 Reducing nutrients in storm water.
- Building storm water treatment plants, which reduce the content of biogenic elements
1.4 Creating a taxation system to promote cause-based treatment of storm water, as well as construction and maintenance of storm water systems.
1.5 Enhance regular cleaning performance of the urban space, streets and gullies (particularly in the early spring) in order to reduce pollution carried into the environment by storm water.
1.6 Developing the concept of snow storage, determination and construction of planned storage sites.
2. Developing international cooperation between all countries bordering the Baltic Sea to achieve good environmental status for the sea.
3. Exploring the impact caused by high-speed ferries to the coastal sea of Tallinn and developing corresponding mitigation measures..
4. Improving the monitoring of enterprises with environmental risk in order to prevent pollution incidents. Strengthening the monitoring of pollution prevention.
5. Motivating owners to join the public sewerage system built to connect the registered immovable in their possession. Minimization of local wastewater treatment in the urban space.