From typicallyspanish.com

Costa Cálida
Closed beach in Los Urrutias has reopened for bathing
By m.p
Jul 31, 2007 - 6:09 PM

Part of the beach in Los Urrutias remained closed for bathing on Tuesday morning, after the decision on Monday to fly the red flag in a 35 metre section of El Tallo Beach. The reason given in some reports was a green-coloured slick and dead fish washed up on the shoreline.

Cartagena Town Hall said the beach was reopened at 1pm on Tuesday after analyses showed the slick to be algae and did not pose any danger to the public.