The document Tianjin ecological protection “red line" issued by Tianjin city declares a total area of 1,393.79 square kilometers, 9.91% of the total land and sea area of the city, to be under mandatory and rigorous protection. 

The red line area includes 1,195 square kilometers of land, or 10% of the city’s total; 219.79 square kilometers of marine area, 10.24% of Tianjin’s ocean space; and 18.63 kilometers of coastline, 12.12% of Tianjin’s shores.

The ecological red line is meant to protect regions with important ecological functions or fragility through water and soil conservation and biodiversity maintenance.