Riparian forests play a vital role in conserving biodiversity, maintaining ecological connectivity and assisting the delivery of key ecosystem services (i.e. maintenance of water flows). Nevertheless, riparian forests are particularly threatened across the tropics, including in Brazil following widespread forest conversion for pasturelands and agriculture. Despite the significance of the landmark Brazilian Forest Code as the basis of environmental protection on private properties, the effectiveness of the legal protection afforded to riparian vegetation in permanent preservation areas (APP, in Portuguese) has been very poorly assessed. We provide the first fine-scale estimation of the total riparian APP distribution and deficit for the 1.25 Mkm ² Brazilian state of Pará which has the highest deforestation rate in the Brazilian Amazon in recent years, using the available properties boundaries. We demonstrate how coarse-resolution mapping data (for landscape scale mapping, e.g. 1:100,000) consistently underestimates the extent of APP areas, highlighting the scale of the challenge involved in achieving compliance with the Brazilian Forest Code. Moreover, despite nearly half (49%) of the total extent of riparian APPs being forested, following the 2012 revision of the Forest Code, the area that does not need to be restored is six times the area obligated for restoration (940,000 ha). This suggests that some catchments in Pará may not recover fully functioning hydrological and ecological services, as around 5.7 Mha of already cleared APP are likely to remain deforested because there was a law amnesty. We also found that deforestation within APPs was greater than outside APPs for most municipalities in Pará indicating that implementation of the Forest Code has not been sufficient to protect riparian forests to date. This shortfall in the legal requirement to restore riparian forest cover suggests that under the current enforcement regime regulatory measures on their own are insufficient and incentive-based mechanisms are needed to encourage restoration – even within the existing legal framework. Our work demonstrates the importance of using finer resolution land cover data and improved hydrological models for ensuring the effective implementation of Brazilian legislation and the safeguarding of the environmental benefits provided by these critically important ecosystems.