IWRA Proceedings

<span title="\&quot;En" la="" parte="" donde="" se="" ingresa="" mayor="" de="" las="" descargas,="" cuenta="" con="" cerca="" 40="" ha="" tule,="" que="" bien="" manejado="" puede="" ser="" utilizado="" como="" un="" humedal="" natural="" para="" el="" mejoramiento="" calidad="" agua="" entra="" a="" laguna.\"="">Cajititlan Lake is the second largest lake in Jalisco, located in Tlajomulco´s municipality, with an approximate surface of 2000 ha.  It is a shallow lake with an average depth of 3 m.  The lake has been impacted for many years from different anthropogenic pressures as water mangement for irrigation and discharge of untreated sewage.  This pollution has dramatic effects on lake and has affected the biodiversity in it, having also an important economic impact for inhabitats of the local comunities.   From 2009, started presenting massive deaths of fish, and continuing repeted in 2010,2011, 2013 and in a more striking way in september 2014 with the death of almost 200 tons of fish.    The lake is located in a closed basin, so all management done in upper areas have impact in water quantity and quality of the lake.   The aim fo this research  was to find the spatial distribution of pollutants and identify the source of origen using a geographic information system. During the period of september 2014 to september 2016 a monthly water quality monitoring was conducted with 61sampling sites established throughout the lake, to let us know the spatial and temporal distribution of pollutants.   The sampling a depths 0.5 m and 1.5 m was made and measured with a multiparameter, the concentration of dissolved oxygen, electrical conductivity, pH, temprature, potential redox and turbidity.   Besides water deph and visibility using Secchi disk.   The results show a significant variation in oxygen concentration across the lake, keeping the area near downloading an anoxic zone, and other areas where the daily dynamics of oxygen can be moved from near zero to supersaturation during the day by the process of photosynthesis by abundant green algae found as a product of euthropication process.   The visible Secchi disk depth is jut 10 to 12 cm resulting in this an indicator of high level of eutrophication.   pH values averaged values greater tha 9 units in virtually all sampling sites, giving high alkaline values.   the comparisonof the result achieved in dry and rainy indicate that eh anoxic zones moves during rainy season by growing runoff income from the southwest of the lake.   Moving wastewater to mayor part of lake in a short time, we thing is the cause of fish kill.   Stategies for pollution control should begin from zero discharge of untreated wastewater entering the Cajititlan lake.    In zone where there is deposited most of unloads, there are about 40 ha of Typha, that well.managed can be used as a natural wetland to improve the quaity of water entering the Cajititlan lake.