Case Studies - Coastal Lagoons: Ecosystem Processes and Modeling for Sustainable Use and Development - page 433

The following final recommendations on Vistula Lagoon management were
developed on the basis of modeling: 20

• The study 19 revealed the vital necessity to focus attention on nonpoint
pollution sources in the coming years. The sustainable development of
agriculture in the catchment area will hopefully result in an improvement
in the ecological state of the lagoon, especially in the Polish part.
• The water quality in both the Polish and Russian parts of the lagoon mostly
depends on the local action taken to reduce nutrient loading. This conclu-
sion strongly forced national authorities to apply local remediation mea-
sures instead of complaining about negative influence from the neighbor.
• The water quality in the southern Polish part of the lagoon is more sensitive
to pollutants because the water retention time there is longer than in the
northern Russian part. It is a clear example of difference in local flushing
time (see Chapter 6.3.3.1.2) for various parts of a lagoon.
• It was concluded that limiting eutrophication processes in the Polish part
of the Vistula Lagoon may be achieved by reducing the nitrogen and
phosphorus loads from the Polish part of the catchment area. High loads
of nutrients from the Russian part of the catchment area do not have a
significant impact on the ecological state of the Polish part of the lagoon.
• It is presumed that the position of the planned outlet from the new
Kaliningrad treatment facility to the Kaliningrad Navigational Channel
that passes along the northern coast of the lagoon is not optimal since
backward wind surge currents can transport the water toward populated
areas near Kaliningrad.
• Due to complex water circulation between the Kaliningrad Navigational
Channel and the Vistula Lagoon, it was recommended to establish a local
fine-grid model. This model has to include the channel area to simulate
the water quality in this part of lagoon and to identify the optimal situation
between the costs involved and the environmental benefits achieved.
• The results of the scenario Prognosis 2010 and scenario (3) (which rep-
resents the best situation in terms of pollution load) indicate that the
anticipated situation in the Vistula Lagoon ecosystem regarding eutroph-
ication processes can be improved significantly.

• However, achieving such improvements requires effort and investment in

the catchment area in order to achieve significant reductions in nonpoint
nutrient run-off. Wetland restoration, reforestation, adequate regulation,
and agricultural education should all be conducted. Simultaneously, point-
source wastewater treatment technologies should be modernized.

Numerical modeling conducted during the project 19,20 has proven to be useful
in the process of preparing impact assessments of different pollution sources located
in the catchment area, as well as in evaluating the effects of alternative abatement
actions. The conclusions drawn from the modeling study are valuable guidelines for
the regional authorities responsible for environmental protection.