Monitoring programs are among the first steps to develop robust management strategies, especially in international transboundary waters. Understanding how water quality parameters are impacted by different types of land use promotes a baseline for stakeholders to define the best governance for the management of water resources. Seeking to provide this type of information, we sampled 24 streams – 12 in Brazil and 12 in Paraguay – in February, April, July, September, and November 2019. We determined water quality parameters, grouped into three categories: morphometric, physical and chemical, and nutrients. We explored differences in water quality parameters between countries, and over a one-year sampling. We also tested whether Brazilian and Paraguayan streams are impacted by agriculture, urbanization, and forest cover. Finally, we performed a partial RDA to test the influence of land use on water quality parameters and controlled spatial autocorrelation by including spatial variables (dbMEM) as a condition. Most of the water quality parameters showed significant differences between countries; only turbidity, and pH, presented significant differences between countries and sampling periods, and only water temperature varied significantly along the year. We did not find evidence that different types of land use are causing physical and chemical variance in Brazilian and Paraguayan streams (R² = 0.06, p = 0.68). In conclusion, the results evidenced that the main differences in the water quality parameters occur between countries. Based on the results, transboundary governance can use these data to implement integrated water resources management cooperation.

监测计划是制定稳健管理战略的第一步，尤其是在国际跨界水域。了解水质参数如何受到不同类型的土地利用的影响，可以为利益相关者提供一个基线，以确定水资源管理的最佳治理。为了提供此类信息，我们于 2019 年 2 月、4 月、7 月、9 月和 11 月对 24 条溪流进行了采样，其中 12 条在巴西，12 条在巴拉圭。我们确定了水质参数，分为三类：形态测量、物理和化学, 和营养素。我们探索了国家之间水质参数的差异，并进行了一年多的采样。我们还测试了巴西和巴拉圭河流是否受到农业、城市化和森林覆盖的影响。最后，我们进行了部分 RDA，通过将空间变量 (dbMEM) 作为条件来测试土地利用对水质参数和受控空间自相关的影响。大多数水质参数在国家之间表现出显着差异；只有浊度和 pH 值在不同国家和采样期之间存在显着差异，并且只有水温在一年中变化显着。我们没有发现证据表明不同类型的土地利用导致巴西和巴拉圭河流的物理和化学变化（R² = 0.06，p = 0.68）。总之，结果表明水质参数的主要差异发生在国家之间。基于结果，跨界治理可以利用这些数据实施水资源综合管理合作。