Environmental impact and volume for the proposed tunnel in the Metztitlán lagoon, Hidalgo, Mexico

Abstract

This investigation is aimed at assessing the possible environmental impact in the event of the construction of a third discharge tunnel in the Metztitlán lagoon, in the Barranca de Metztitlán Biosphere Reserve. An additional objective is to justify the discharge regime that would permit protecting the environment. This tunnel was designed by the National Water Commission (CONAGUA) in order to reduce flooding of Irrigation District 08, which occurs every 2.5 years, on average. This work applied two environmental impact assessment methods: the Matrix of Importance and that developed by Battelle Columbus, with which the potential impact on terrestrial and aquatic biodiversity in the Biosphere Reserve were qualitatively and quantitatively determined. The impact is assessed by means of 42 parameters for environmental conditions. It is estimated that the overall impact of the project would have little significance, though there would be some. The contribution of this investigation is the recommendation that the water discharge through the tunnel be done using such a regime, that each year the water area in the lagoon be maintained at levels corresponding to 60% of the mean monthly inflow into the lagoon in order to prevent negative impact and reduce those that are unavoidable.