4.2.1 Turbidity
Analysing the turbidity data, suspended solids, phosphorus and dissolved organic carbon (Figures: 3 - A, B, C, and D), it ensures that the data from treatment T2 are more uniform or stable than in T1 for these indicators. When analysing Figures 3A and 3B, related to water turbidity, in previous years the implementation of the study (T1) and after the implementation of the study (T2), it observes that, on average, water turbidity was lower in the months of February and December when we compare (T2) with the situation before the implementation of the study (T1). For the T1 treatment, the values were higher than the CONAMA standard (Conama, 1986), which is 100 NUT (Figure 3A), in the average of February and December. In T2 treatment, the average values were 102 NUT, except for February 2009, 2014, 2017 and 2018; October 2009, 2012 and 2018; December 2009 and 2015 (Figure 3B). This difference seen in T2 can be explained by the decrease in the supply of sediments in the watercourse. It happened because of the effects of the change in soil management with the adoption of conservationist practices and erosion control through the implementation of technical projects at the 196 properties that were recovered with conservationist agriculture, through the work performed (Figures 3B, 3D, 3E, 3G, 3I, 3K, 3M and 3O). A similar result was found by Souza & Gastaldini (2014), who observed that land use significantly influenced the water quality parameters. In areas considered to have a higher percentage of agriculture and with problems related to erosion, the situation of the area before the implementation of constructions, the parameters of turbidity, suspended solids are higher. This land use, without adopting conservationist practices, can be considered as having the biggest potential for erosion.