This guide covers the law governing the use, protection, and regulation of water and the land beneath and beside it. Part one sets out the three allocation systems — riparian rights, prior appropriation, and the several competing groundwater doctrines — including how rights are created, measured, transferred, and lost. Part two covers the federal regulatory overlay: the Clean Water Act's discharge and dredge-and-fill permits, the definition of jurisdictional waters after the Supreme Court's decision in Sackett, state water quality certification, total maximum daily loads, and enforcement including citizen suits. Part three works through wetlands practice from delineation to jurisdictional determination to the avoid-minimize-mitigate sequence and the permit tracks available. Part four covers conservation easements as both preservation instrument and tax deduction, with the drafting provisions that determine whether they hold up. Part five addresses the constitutional limits on permit exactions and the takings framework. Part six covers surface water drainage between neighbors, and part seven covers diligence for buying land with water on it. Worked examples, comparison tables, and cross-references to related UpLaw resources run throughout.