This chapter provides an overview of Directive 91/676/EEC, which aims to protect water resources from pollution by nitrates from agricultural source. An important aspect of this Directive is the identification and delimitation of Nitrate Vulnerable Zones (NVZs), areas identified as being at high risk of nitrate pollution and subject to specific regulatory measures. Furthermore, the chapter reports a methodology for slope calculation, which is crucial for assessing runoff potential and subsequent nitrate leaching and comprehensive case studies on livestock manure management technologies, highlighting innovative practices for reducing environmental impact.