SCH Number 2025041173

Project Info

Title

Johnson Slough Recharge Project

Description

The CPDC is proposing to develop a recharge basin on a property north of the Johnson Slough east of the Kaweah Oaks Preserve along Road 182, north of Highway 198. The Project is anticipated to include an approximately 18-acre basin that is an off-stream basin diverting from Johnson Slough. It is also anticipated there will be an ability to return water from the new basin back into Johnson Slough for potential use downstream. The Project would assist CPDC in expanding its groundwater recharge efforts in response to the 2014 Sustainable Groundwater Management Act (SGMA). The Project would include a turnout structure with a capacity for approximately 20 cubic feet per second. The proposed turnout facility would allow CPDC to divert surface water from Johnson Slough into the proposed basin area to increase groundwater storage. The proposed facility would consist of cast-in-place concrete structure, control gate(s), trash rack, and related appurtenances from the north bank of the Johnson Slough to divert to the proposed basin. The turnout structure would connect to an inlet structure approximately 150 linear feet (LF) from Johnson Slough in a proposed distribution channel through reinforced concrete piping, equipped with a metered connection. The diversion structure excavation depth would be up to 15 feet below ground surface for establishing proper compaction under the structure and pipeline. Almost all this excavation material will be put back in place. The Project would also include conservation space in the way of native plant species planting. Native habitat plantings would be located along the perimeter of the proposed recharge basin and species would be chosen in accordance with the recommended species outlined in the Kaweah MLRP Vegetation Outline document found in Appendix D. Construction would include equipment mobilization, excavation of earthwork for the recharge basin, and construction of basin perimeter berms. As standard practice, basin perimeter berms would be designed in accordance to be used as access roads for operation and maintenance (O&M) purposes. The Project site would contain temporary staging areas for construction equipment and material storage during the construction effort. Staging would not be located along or near Johnson Slough and would be located on an elevated surface away from basin construction. Basin construction would also include performance testing and demobilization. Excavation material would be used on site for berm construction along the perimeter. Any excess material would be exported off site. New berm construction would not exceed six feet in height, measured from the exterior toe to the top of new berm. The maximum depth of ground disturbance for the basin would be as much as nine (9) feet. The site is currently devoid of vegetation so no tree or vegetation removal is needed. Portions of the site have been recently disturbed by earthwork activities. Through the development of this proposed recharge basin, it is anticipated to recharge approximately 450 acre-feet (AF) in years water will be available. This is derived by an estimated recharge rate of 0.5 AF per acre across approximately 18 acres of wetted area. Assuming surplus water is available for approximately 50 days equates to the approximate 450 AF recharged. 50 days is that average annual amount of surplus surface water availability on the Johnson Slough system.

2 documents in project