Energy production in concentrating solar plants is influenced by different types of losses that reduce the efficiency of the system. One of the most relevant parameters is the reflectivity of the mirrors, which indicates the fraction of incident solar radiation that the mirrors can reflect. This variable is highly dependent on the soiling of the mirror surface, which reduces the ability to reflect incident radiation, thus decreasing energy generation. Different authors have studied reflectivity, soiling, and dust accumulation in concentrating technologies through the analysis and modelling of these factors and their main effects. However, there is still a lack of information available on specific technologies such as linear Fresnel collectors, even though soiling causes higher losses compared to technologies like photovoltaics. Many of the studies used samples of mirrors exposed to soiling rather than actual measurements on operating Fresnel plants. In addition, there is no data to show whether the soiling is distributed uniformly across the solar field, or if the location of the mirror rows and the surrounding environment influence the reflectivity variation. In this work, the distribution of reflectivity values in different zones of a Fresnel installation was analyzed under real operating conditions. The solar plant had four modules and was exposed to vehicle traffic in an industry located in an agro-forestry environment. Twelve points distributed over the entire solar field were selected, and more than seventy weekly or bi-weekly reflectivity measurements were carried out in six stages separated by manual mirror cleanings. A portable reflectometer was used to collect reflectivity data. Measurements were grouped by module and by zone, mean values and standard deviations were calculated, and a statistical analysis was performed using control charts. It was observed that soiling was slightly higher in the modules and mirror rows that were more exposed to the surrounding natural environment and the vehicle traffic area. However, the differences between the values of the different zones were not very significant. The largest deviations were observed for mirrors with operational failures resulting in different exposure times of the reflecting surface, demonstrating the importance of this factor.