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One common denominator was water quality monitoring —all projects were held to the <br />same high standards to ensure groundwater protection. The consistent demonstration <br />monitoring requirements created an economic inequity that tended to favor municipal <br />applications with higher water values versus agricultural applications that often tend to <br />favor simple recharge methods due to economic constraints. <br />Recharge Technology Characteristics <br />The questions regarding allocations of benefits and costs, economic feasibility, and legal <br />authorities are directly tied to the various scopes and approaches inherent in the types of <br />recharge methods. This can be illustrated by grouping methods into three categories. <br />Direct Well Injection — This highly controlled recharge method is primarily used for <br />individual facilities on a local scale (e.g., an aquifer storage and recovery program used to <br />meet seasonal supply demands). The injectate can be tracked and recovered relatively <br />easily. This is the most intensive type of recharge with the highest level of technology and <br />requires greater investment in construction, operations, and maintenance. When the water <br />source is other than treated drinking water, on -line monitoring and automated shutdown <br />systems are needed to protect groundwater from direct contamination. <br />Surface Infiltration —This typically refers to spreading basins constructed at sites with <br />permeable soils and subsurface conditions suitable to allow percolation down to recharge <br />unconfined aquifers. The costs are lower due to passive operations and less maintenance. <br />Water pretreatment costs may also be lower depending on the water source. The natural <br />soil treatment properties have been exploited in some applications to improve water <br />quality during recharge. Water recharged this way cannot be tracked as easily as well <br />injection, and the effectiveness depends on the available water and site specific conditions. <br />Hydrologic Management Practices — This category includes land practices applied <br />to induce greater natural surface infiltration and watershed practices such as temporary <br />instream measures used to increase recharge. These practices need to be integrated with <br />ongoing resource activities (e.g., crop production), or watershed practices (e.g., floodplain <br />management). Widespread implementation could contribute to replenishment but requires <br />long -term planning, support, and coordination. Watershed programs often cross political <br />boundaries and must overcome any institutional barriers and work closely with existing <br />resource programs to ensure goals and methods are compatible. <br />These basic categories of recharge technology form a gradient in: <br />• Scope (from a site - specific approach to a basin -wide approach) <br />• Objectives (from localized benefits to watershed benefits) <br />• Construction (from most construction needed to least construction) <br />• Technical considerations (from most complex to simplest) <br />• Economics (from expensive direct benefits to low -cost widespread benefits) <br />Executive Summary E7 <br />