Eutrophication of Laguna de Paca and Its Consequences – Peru

The micro-basin of the Paca Paccha river is composed of surfaces made up of cultivated fields, forests, natural pastures and rocky areas. On this surface, there are rains with high intensities which cause runoff. This runoff erodes the surface of the micro-basin. These runoff waters transport the organic material that is made up of the fertilizers applied to the crop fields, which finally reaches the Paca Paccha river. This phenomenon occurs during intense rainy seasons, to finally flow into the Paca lagoon, becoming clogged at the bottom of said lagoon, the same one that quantifies a volume of 20.36 m³, this being one of the causes of the eutrophication process. On the other hand, the lagoon is bordered by cultivated fields that directly by runoff drag organic matter to the edges of the lagoon, which favor the propagation of vegetation such as reeds, the same that caused the eutrophication of these areas by the contribution of organic matter. Due to this cause, the Paca lagoon has a eutrophied surface of 1.46 km². The surface that is in the process of eutrophication corresponds to 0.04 km²and the free surface that has not yet reached this process is 3.05 km². Once the physical-chemical analysis of the lagoon waters has been carried out, they give us a result of 170 ppm of SO₄ 2_-, 85 ppm of PO₄ 2_-, 28 ppm of NO_3-, 5.3 ppm of O₂, color 3.5, turbidity 1.9, total hardness 33, hardness of calcium 15 and PH of 8.7. These results show that the degree of eutrophication is light to medium. To prevent the lagoon from continuing with the eutrophication process, in this way the contaminated water reaches the lagoon directly, for this it must be treated with treatment plants that include biological and chemical treatments that eliminate phosphorus and nitrogen. In addition, it is proposed to build a sand trap at the entrance of the lagoon to trap the material dragged by the river.