Murcia Government takes steps towards saving Mar Menor

The largest saltwater lagoon in Spain might be facing an ecological collapse

Today in San Javier, Murcia, there was a meeting of the Forum for Inter-administrative Coordination of Mar Menor, which was presided by Antonio Luengo, Regional Minister for Water, Agriculture and Environment. It was announced that 48 initiatives will be undertaken to save the fragile ecosystem of the Mar Menor lagoon and 122.6 million euros will be invested to that end.

The funds will go towards improving the sewerage system of communities around Mar Menor

The projects that were discussed and announced at the meeting are part of the larger Program for Control and Improvement of the Rainwater Runoff Network and Sewage Treatment Plants 2020-2030. In its essence, the idea is to move towards creating separate networks for directing and collecting sewerage and stormwaters.

"We pursue the objective of separating rainwater networks from sanitation networks, due to the significant difference in the polluting load of both types of water," explained Minister Luengo, adding that "on one hand, there will be an obligation to install separate networks in all new urban developments around Mar Menor, thus promoting different treatments for these networks, while in already existing residential areas, the possibility of establishing new specialized rainwater networks is foreseen, which would reduce the volume of water introduced in unitary systems".

It may appear surprising but in the case of Mar Menor, it is actually the rainwaters that are considered more harmful for its fragile ecosystem. Last year there was a lot of concern after a large amount of fish were found dead on the surface of the lagoon.

The reason is in the specific biological and physical make-up of Mar Menor, which is separated from the Mediterranean Sea by a narrow sand strip. Torrential rains cause nitrogen and phosphorus from surrounding farmed soils to be washed into the lake, which in turn causes the increased growth of algae.

When there is an algal bloom the top layer of the water body becomes dense and does not let sunlight penetrate deeply. This, in turn, makes the bottom of the lagoon oxygen-deficient and essentially a dead layer.

Fish and crabs seek refuge at the top layer; however, strong winds can push it to the side allowing for the dead layer to resurface trapping the animals and essentially suffocating them. That is why it is important to measure oxygen levels, salinity, turbidity and chlorophyll levels, as these are the essential indicators whether the ecosystem is balanced.

The most important among the planned projects are the installations of rainwater drains and collectors and anti-overflow prevention systems for the unified sewerage lines.