## 13 Legal Approaches of Foreign Countries: The US, Australia, and in the European Union  
Various forms of surface water, such as rainwater, river water, treated wastewater, and other recycled water, can be used as source water for ASWQE depending on the area of application or type of technology. Thus, legal rights to surface water can be considered one of the key legal issues that may affect ASWQE projects [9]. In the US, issues regarding the right to surface water are regulated by individual states. In general, states in the Eastern US preferentially grant the right to surface water to the landowner adjacent to the surface water, such as a river, based on the traditional concept of riparian rights. Nevertheless, the amount of use is limited and regulated through the permission of the state. On the other hand, states in the Western US grant the right to use water based on the prior appropriation doctrine or first-in-time, first-in-right principle, while also setting the scope of use according to the permission of the authorities [6; 9; 30; 31]. In relation to ASR/ASTR projects, representative examples of states that have statutes concerning the right to surface water as source water, including permission provisions, can be Oregon (Or. Rev. Stat. $ 537.534 (2003)), Idaho (Idaho Code Ann. $ 42-234(2) (2006)), Kansas (Kan. Admin. Regs. $ 5-12-1 et seq.), Arizona (Ariz. Rev. Stats. $ 45-801.01 et seq. ), California (Cal. Water Code $ 1242 (2006)), and Texas (Tex. Water Code Ann. $ 11.153 (2005)) [9]. Meanwhile, according to the prior appropriation doctrine, surface water may be treated separately from groundwater since the surface water is regulated by the state's permit system based on the doctrine of priorities, while the right to groundwater is considered to be part of private land ownership [32]. As stated above, ASWQE projects use various forms of surface water which are physically, hydrologically, or environmentally connected with groundwater. They mutually and continually influence each other through channels. Therefore, the integrated or conjunctive management system has been pointed out as an important element in performing ASWQE projects [9; 33]. In the US, particularly in the western states in which surface water and groundwater are regulated under the prior appropriation doctrine, judicial decisions and laws have established the \"groundwater-surface water management\" (or \"conjunctive management\") system of surface water and groundwater. They have considered the conjunctive management system as an essential part for ASR projects [34]. In 1976, the US Supreme Court ruled that \"groundwater and surface water are physically interrelated as integral parts of the hydrologic cycle\" [32; 35]. Wyoming, Idaho, Colorado, and Washington are representative cases that have some common provisions relating to the conjunctive management based on the prior appropriation doctrine as the guiding principle in their constitutions or statutes (Wyoming Constitution, Art. $ 3; Idaho Constitution, Article XV $ 3; Colorado Constitution, Article XVI $ 6) [33; 34].  
In Wyoming, anyone who wants to use groundwater must apply to the State Engineer for permission (Wyoming Statute $ 41-3-930(a)). If the surface water and groundwater in a specific area are determined to constitute \"one source of supply\" by the State Engineers, they shall be managed under a single set of priorities (Wyoming Statute $ 41-3-916). The Board of Control, the state authorities to administer groundwater supplies, may designate particular areas as \"control areas\" under certain circumstances (Wyoming Statute $ 41-3-912).