## 2 Definition and Main Legal Issues of ASWQE
### Main Legal Issues  
In addition to the research and development (R&D) activities related to the total solution technologies and the pilot project O&M, the ASWQE Research Group is also conducting research on relevant regulatory/institutional foundations for the sustainable and reliable development and long-term operation of the ASWQE project. The authors used the issue tree analysis method [17] to identify the most pressing problems in relation to ASWQE project development and operation based on consultations and collaborative works with water resources and legal experts through a series of workshops. The authors derived major criteria and subjects considering the identified problem and then devised questions in relation to these subjects, using this as a foundation to compare and review the contents of domestic and foreign statutes, regulations, and policies (see Figure 2).  
Many countries have tried to resolve various legal issues by establishing related acts and legislation either directly or indirectly. However, the authors could not find any cases of an integrated and uniform legal system at the national level up to now. For example, in the US, there have been some statutes relevant to ASR/ASTR projects at the federal level, such as the Clean Water Act, Underground Injection Control (UIC) Program under the federal Safe Drinking Water Act, etc., while several states have developed their respective UIC regulations, statutory schemes or programs of underground storage of water, drinking water standards, rules of water reuse or recycling, etc.. However, it has been pointed out that there are inconsistencies not only between the federal regulatory requirements and states' regulatory standards, but also between the Clean Water Act and the Safe Drinking Water Act [9].  
Figure 1: Concept and scope of the aquifer storage and water quality enhancement project (ASWQEP) and legislation requirements. WTP: Water Treatment Plant.  
Therefore, efficient establishment and implementation of a related legal system are considered a key factor in determining the success of such projects [9; 18].  
Similar to other countries with experience in carrying out ASR/ASTR projects, such as the US, Australia, and several European Union countries, Korea also faces diverse and complicated legal issues for each phase of ASWQE projects. Legal issues that emerged throughout the various phases of the project were first analyzed (Figure 3). The blue boxes include prerequisites to be considered and addressed legally throughout the project, whereas the yellow boxes include individual items and factors to be considered and addressed at each stage in the implementation of the project.  
Figure 3: Main legal issues and components in each phase of the ASWQE project.  
Figure 2: Issue tree analysis for the aquifer storage and water quality enhancement (ASWQE) projects in Korea. MAR: management of aquifer recharge.  
A few of the most essential issues can be summarized as follows: (i) separation between the rights to develop or use the aquifer to cope with groundwater shortages and the ownership of the land above the aquifer; (ii) rights to surface water that is used for aquifer storage; (iii) rights for groundwater injected and recharged in the aquifer; (iv) issues surrounding the purpose of pumping/supplying restored water and related rights; and (v) issues of governance, such as the subjects of implementing the project in all processes as well as licensing/permitting systems.