The urban development of Brazilian cities occurred from the occupation of riverbanks since the first urban centers began to exist, when population migrated from rural areas to the urban area, seeking for better living conditions (MINISTÉRIO PÚBLICO FEDERAL, 2018). The sustainable use of these spaces becomes, then, an important factor to consider as society strategically shapes and grows around them. According to data provided by IBGE Demographic Census, Brazil surpassed the mark of 203 million inhabitants in 2023. Of these, 84% are considered urban population, and half correspond to inhabitants of large cities. The percentage of residents living in informal occupations such as slums, irregularsubdivisions, and other types of housing precariousness, ranges from 30 percent to 60%.According to Gordilho-Souza (2018), these numbers correspond to people who livein submission to legislation, optionally or not, but certainly excluded from urbanbenefits. Therefore, the state assumes a dichotomous role related to irregularoccupations. The dichotomy begins with the absence of effective policies for socialhousing, causing the population in need of a place to live to settle in irregular riskareas without proper supervision and monitoring. In a second moment, after theconsolidation of these occupations, when people already feels that they belong tothe place and develops its family, fraternal and economic networks, the State oftenenters these territories in an attempt to regularize, apply the law belatedly, throughmeans of removal to other areas that should have been assigned to these residentsin the first moment, where the demand for regular housing was observed.The land regularization instrument is registered in Brazil since the approval,and subsequent publication, of the City Statute, through Federal Law 10,257/2011.The regularization of housing located within APP project areas, however, becamepossible after the enactment of Law n. 13,465/17. The process of Urban LandRegularization (Reurb) was instituted, under the scope of (...) legal, urban,environmental, and social measures aimed at the incorporation of informal urbancenters into the urban territorial ordering and titling was established of itsoccupants. (BRASIL, 2017). Reurb is branched into two modalities: Reurb of Social Interest (Reurb-s) applicable to informal urban centers occupied by low-income population , andReurb of Specific Interest (Reurb-e), in which land regularization is applicable tothe residents who do not qualify for Reurb-s (BRASIL, 2017). The lack of regularity around the area of the Reurb project requires adjustments that agree with eachother in the administrative, legal, tax areas, in addition to other issues considered relevant when dealing with the urban, social and environmental approach of the project (LOCATELLI, 2021). It is necessary to advance in the creation of public policies that address the theme, as well as the increase of scientific productions that are dedicated to the debate. This study, therefore, becomes applicable when analyzing the referencecase of Mambucaba s river regarding the Reurb instruments, applying in a practicalway to the studies required for the implementation of a project to regularizeoccupations in APP, considering the complexity of legal, social, urbanistic, andenvironmental. The Costa Verde region, located on the southern coast of the state of Riode Janeiro, presents a unique complexity for the pursuit of sustainable development. The municipalities that comprise it have rugged relief from Serra do Mar, in the north, to the seacoast, in the south. This great difference in altitudes promotes the concentration of rain on the slopes, which flow with great intensity to the lower terrain, forming a diverse water network and flowing into the Atlantic Ocean. The area chosen for the development of the work is called Parque Mambucaba, the largest neighborhood in Angra dos Reis in terms of population. Its boundary is the adjacent municipality of Paraty, and its municipal limit isestablished by Mambucaba river. The number of approximately 25,000 peopleresiding in the neighborhood multiplies on weekends and holidays throughout themonths of December to March or, even, when there is a job offer in the constructionworks of the nuclear power plants of Angra dos Reis, just 8,7 miles fromMambucaba Park neighborhood. The neighborhood has a history of constant flooding in rainy seasons, and there is a worsening of floods as the neighborhood grows, with more homes, soil sealing and irregular occupations.The study of Filho et al. (2017), mentions that approximately 47.1% of thepopulation residing in the Parque Mambucaba neighborhood are affected byfloods. Therefore, approximately 12,000 people constantly suffer the impacts ofthe lack of planning and public policies in the locality.According to the City Hall, among the advantages of Reurb-s are thesimplicity of the process, which is entirely paid for by the City Hall. It also includesproperty appreciation; facilitated access to financial credit system; andguaranteeing real estate credit in the event of sale or construction (ANGRA DOSREIS, 2023). With such development, residents can increase their income with theaddition of tourists and vacationers in the region, in addition to investing in theirown homes that would not be affected so often by the floods of the Mambucabariver and the lack of rainwater drainage. It is understood, therefore, that it is of common interest between the Municipality of Angra dos Reis, the Public Ministry, INEA and the residents, to seek the land regularity of the allotment through the Reurb instrument, as observed in other municipalities in the south of the state from Rio de Janeiro, such as Resende, Itatiaia, Barra Mansa and Volta Redonda.