TITLE:
The Mexican Environmental Flow Standard: Scope, Application and Implementation
AUTHORS:
María Antonieta Gómez-Balandra, María del Pilar Saldaña-Fabela, Maricela Martínez-Jiménez
KEYWORDS:
Environmental Flows; Hydrological Methods; Mexican Standard
JOURNAL NAME:
Journal of Environmental Protection,
Vol.5 No.1,
January
23,
2014
ABSTRACT: With the
implementation of the Official Mexican Standard NOM-011-CONAGUA-2000 [1], the
water balance of 730 basins has been calculated and its water availability
agreement is published. This rule points out to allocate water for the
environment only as an annual volume since methods for estimating environmental
flows were not standardized in the country. For this reason, The Water Agency
(CONAGUA) issued the standard NMX-AA-159-SCFI-2012 [2], to assess environmental
flows needed both, at the strategic level in Integrated Water Resources
Management (IWRM), or as part of the Environmental Impact Assessment (EIA) of
large hydraulic projects. For over ten years, this standard was developed and
finally published in September 2012 [3]. It explains different methods from
hydrological to holistic approaches, with examples for the country. Its
application will cover the urgent need to preserve water for ecosystems in
watersheds with high ecological importance and low stress for water use. In
this paper, an analysis of the environmental flow standard and examples of the
suggested hydrological methods are presented. For its implementation, some
steps are taking place, mainly establishing environmental water reserves and
building capacities. In addition, environmental allocations are becoming a
common practice for all water projects, as well as setting limits to
hydrological alterations by hydroelectric dams. The standard promotes the use
of technical integration tools to analyze the responses of ecosystems to
changes in the flow regime and adaptive management under different scenarios of
water use. Although the main steps have been taken, its implementation as mandatory
rule will take time.