SECTION 5.0 WATER MANAGEMENT STRATEGIES USED TO MEET PLAN OBJECTIVES 5.1 Overview of This Section Included in the State’s IRWMP Guidelines (Appendix A, Plan Standards) are 20 water management strategies to be considered for implementation as part of an IRWM Plan. Of the 20 water management strategies, 11 of them are required to be addressed in a Plan (see below). Because all 20 water management strategies are currently being implemented within the Region and are consistent with the IRWM Plan objectives, the Watersheds Coalition of Ventura County (WCVC) determined that all of the strategies would be discussed in the Region’s IRWM Plan. Water Management Strategies Ecosystem restoration* Conjunctive use Environmental and habitat protection and Desalination improvement* Imported water Water supply reliability* Land use planning Flood management* NPS pollution control Groundwater management* Surface storage Recreation and public access* Watershed planning Stormwater capture and management* Water and wastewater treatment Water conservation* Water transfers Water quality protection and improvement* Water recycling* Wetlands enhancement and creation* Source: Table A, Appendix A, Integrated Regional Water Management Grant Program Guidelines * Denotes water management strategies which are mandatory, as indicated in the Guidelines In one way or another all of the water management strategies are included as part of local Urban Water Management Plans, watershed management/protection plans, facility master plans, capital improvement plans, habitat conservation plans, flood and stormwater management plans, water conservation plans, water quality improvement plans, groundwater management plans and other plans addressing water supply, water resources and related issues. These plans have been developed and implemented for a variety of reasons: based on local needs and priorities, grant funding availability, regulatory requirements, and/or conditions placed on project approval. Many of the programs and projects currently being implemented in the Region are a direct result of past regional planning efforts. Local agencies have been working collaboratively to implement these strategies since the 1970s (see Section 1 for background on Section 208 Water Quality Management Planning efforts). Implementation of these strategies also achieves the objectives 77 Section 5.0 – Water Management Strategies identified by the WCVC in more recent efforts to address local water problems and enhance water management. 5.2 Water Management Strategies Each of the 20 strategies outlined in the State Guidelines are described more fully below and include the following information: description, benefits of implementation, existing efforts (policies, projects, programs), constraints to implementation (if applicable), related documents and websites, recommended future projects or actions, integration with other strategies, and possible funding sources. ∆ In future updates to the IRWMP these strategy sections may be rearranged to group like strategies together, eliminate duplication of descriptive text and to better integrate the discussion. They are currently listed in alphabetical order. 78 Section 5.0 – Water Management Strategies 5.2.1 Conjunctive Use (Management) Description Through the water management practice of “conjunctive use,” surface-water and groundwater resources can be coordinated to maximize the utility of an area’s collective water resources. Conjunctive use involves using surplus surface water when available (e.g., storm runoff, surplus surface water flows, or recycled water) to recharge groundwater basins containing adequate storage capacity. The surplus surface water may be used to replenish groundwater either by: 1) spreading water on permeable surface areas 2) simply substituting ground water production with surface water deliveries (i.e., in-lieu groundwater storage). The water is then stored in the aquifer so that it may be subsequently withdrawn in dry periods when surface supplies are scarce. 3) by directly injecting water into the groundwater basin through injection wells. All three techniques are used in Ventura County. Considerations in assessing the feasibility of conjunctive use projects, and for improving existing projects, include: • Method of getting the water into the subsurface (spreading or injection), pros and cons • Local hydrogeology • Source water quality and availability • Receiving water quality • Potential geochemical mixing and reactions • Extraction water quality • Beneficial uses of the aquifer • Basin Plan water quality objectives • Regional Water Quality Control Board criteria and process for evaluating the project, and • Point of compliance for water quality objectives Conjunctive use also can work on an inter-basin scale. Water can be transferred from areas with surplus surface water and either stored in another basin or delivered to another basin for use in lieu of groundwater pumping. When surface water is less plentiful, e groundwater can be pumped. This type of conjunctive use has also been implemented in Ventura County. One form of conjunctive use is groundwater banking. In groundwater banking operations, surplus surface water is injected or recharged for storage in the aquifer, and then extracted at a later time when surface water supplies are limited. This form of conjunctive use has also been implemented in Ventura County. Background and Existing Efforts – Local and Statewide Ventura County has some of the most extensive use of conjunctive use facilities in the state. The construction of these facilities was prompted by seawater intrusion within coastal groundwater basins. Seawater intrusion was first detected on the Oxnard Plain in the vicinity of the Hueneme and Mugu submarine canyons in the early 1930s and became a serious concern in the 1950s. Lowered groundwater levels from overpumping, which reversed aquifer flow to onshore (instead of the historical offshore flow) and pulled seawater into the aquifer, formed a distinct pumping trough in the southern Oxnard Plain. 79 Section 5.0 – Water Management Strategies Conjunctive Use Through Surface Recharge The first conjunctive use facilities in Ventura County were temporary diversion dikes constructed in the Santa Clara River; water diverted at these structure was routed to adjacent spreading ponds and percolated into the aquifer. Without these dikes, this diverted water would have otherwise flowed to the ocean along with other stormflow. The Freeman Diversion (1991), which replaced the temporary diversion dikes in the Santa Clara River with a permanent concrete structure, now allows for diversion of river storm flows throughout the winter rainy season. As a side benefit, the Freeman Diversion helped stabilize the riverbed after years of degradation caused by in-stream gravel mining. The spreading ponds connected to the river diversion were expanded several times into the existing Saticoy, El Rio, and Noble spreading basins, which increased the ability of the Freeman Diversion to recharge groundwater. Currently, the Freeman Diversion helps recharge on average almost as much water as is pumped from the groundwater basins that it serves, helping reverse seawater intrusion in the upper of the two aquifers systems beneath the Oxnard Plain. An additional set of recharge basins is currently being developed from unused gravel basins by the City of Oxnard and United Water Conservation District. Conjunctive Use Through In-Lieu Deliveries In addition to surface recharge ponds, the Freeman Diversion also supplies river water to two pipeline systems that deliver this water to agricultural pumpers in lieu of their pumping groundwater. The Pleasant Valley Pipeline delivers this river water to Pleasant Valley County Water District for distribution to pumpers. The Pumping Trough Pipeline conveys diverted river water to agricultural pumpers on the Oxnard Plain, thus reducing the amount of groundwater extractions in areas susceptible to seawater intrusion. When river water is not available, United Water Conservation District uses five Lower Aquifer System wells to pump water into the pipeline. In a different type of in-lieu delivery, United Water Conservation District also pumps and delivers groundwater to the cities of Oxnard and Port Hueneme and Naval Base Ventura County. This water is pumped from wells adjacent to the surface spreading ponds, where the aquifers are readily recharged. The cities and Naval Base Ventura County use this water in lieu of pumping their own wells closer to the coastline, where pumping could pull seawater into the aquifers. 80 Section 5.0 – Water Management Strategies Lake Piru Freeman Diversion Las Posas ASR A newer in-lieu system operated by Camrosa Water District diverts flows from Conejo Creek and delivers the water to Pleasant Valley County Water District to meet local irrigation demands within the overdrafted Pleasant Valley basin. The Conejo Creek Diversion Project diverts a combination of natural stream flow and recycled water released into the creek from wastewater treatment plants upstream. Conjunctive Use Through Inter-Basin Transfers The Conejo Creek project generates credits from the Fox Canyon Groundwater Management Agency by supplying in-lieu water to Pleasant Valley. These credits can then be recovered through the Supplemental M&I Water Program, a joint United Water Conservation District-Calleguas Municipal Water District project. The credits are pumped from the Oxnard Plain Forebay basin adjacent to the spreading