The Reocín mine is located in Cantabrian region, in northern Spain. Its exploitation ended in 2003 due to the exhaustion of its reserves. In November 2004, the controlled flooding of the openpit began. During this process, both the qualities of stored water and piezometric levels have been monitored to control the possible water detraction from the Saja-Besaya hydrographic system. This paper deals with the water chemistry analysis of the pit lake surface, as well as the different conditions of the area. Geological and hydrogeological contexts play an important role in the lake water chemistry. The lake water quality continues improving. The sulphate content and zinc concentrations are already below the permitted pouring limits. Three factors are distinguished: the washing of the mine shafts is completed; the water supply from the aquifer contributes to the dissolution of the salt content and the bedrock, and dolomite, which neutralizes acid waters and improves the water quality during the flooding process with a pH value of 8. Owing to these conditions, the stored water meets the necessary conditions for discharge and provides the opportunities to use it.

Reocín 矿位于西班牙北部的坎塔布连地区。由于储量枯竭，其开采于2003年结束。2004 年 11 月，露天矿控制洪水开始。在此过程中，对储存水的质量和测压水位进行了监测，以控制 Saja-Besaya 水文测量系统可能造​​成的水分流失。本文涉及坑湖表面的水化学分析，以及该地区的不同条件。地质和水文地质背景在湖水化学中起着重要作用。湖水水质持续改善。硫酸盐含量和锌浓度已经低于允许的倾倒极限。区分三个因素：矿井清洗完成；