In Mexico, the National Water Law provides for the use of water reserves, which protect an annual volume of water in a basin for a specific use, including environmental flows. In addition, the Mexican Regulation NMX-AA-159-SCFI-2012 that establishes the procedure for determining the ecological flow in watersheds allows the definition of the amount of water a river needs to complete its ecological functions, not only in terms of annual volume, but also seasonal variations.
In coordination with several academic institutions, non-profit organizations, and government agencies, we have conducted since 2013 the studies needed to determine the ecological flow in eight basins (covering a surface area of 7,108.4 square kilometers) in the states of Durango, Nayarit, and Sinaloa. These basins drain into coastal wetlands of the Gulf of California, including sites of international importance, like the Marismas Nacionales wetland system.
Based on this information, we generated technical and economic proposals to establish environmental water reserves. In 2015, we presented to CONAGUA and to the Watershed Council of the Presidio to San Pedro Rivers a proposal for water reserves in the Acaponeta, Bejuco, Canas, and Rosamorada river basins in the states of Durango and Nayarit. This water reserve guarantees nearly 2 billion cubic meters of water each year (between 33% and 81% of the average annual runoff) as an ecological flow, which will guarantee the flow of freshwater to the mangroves in Marismas Nacionales.
Fotografía: Osvel Hinojosa.