STATE of the WATERSHED – Report on Surface Water Quality the Ventura River Watershed
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STATE OF THE WATERSHED – Report on Surface Water Quality The Ventura River Watershed California Regional Water Quality Control Board – Los Angeles Region May 2002 THIS PAGE INTENTIONALLY LEFT BLANK 2 TABLE OF CONTENTS EXECUTIVE SUMMARY......................................................................................................................... 4 STATE OF THE WATERSHED............................................................................................................... 6 Physical Description of River, Subwatersheds, Reservoirs, and Structures .................................... 7 Groundwater Basins....................................................................................................................... 13 Flows and Precipitation.................................................................................................................. 15 Water Agencies and Water Use ..................................................................................................... 17 Historical Events/Development in Watershed ............................................................................... 19 Biological Setting .......................................................................................................................... 22 Water Resources and Beneficial Uses ........................................................................................... 27 Stakeholder Groups........................................................................................................................ 31 Population, Jurisdictional, and Land Use Characteristics.............................................................. 32 Chronology of Studies, Plans, and Regulations............................................................................. 36 Discharges into the Watershed....................................................................................................... 40 Current Water Quality Impairments .............................................................................................. 41 Historical Water Quality................................................................................................................ 42 Existing Monitoring Programs....................................................................................................... 43 Overview of Existing Monitoring Data ......................................................................................... 46 Recommendations for Future Water Quality Monitoring.............................................................. 51 Summary of Water Quality and Quantity Issues ........................................................................... 51 Regional Board and Other Agency Programs................................................................................ 55 BIBLIOGRAPHY ..................................................................................................................................... 64 3 EXECUTIVE SUMMARY The Ventura River and its tributaries drain a coastal watershed in western Ventura Ventura County. The watershed covers a Los Angeles Co. Co. fan-shaped area of 235 square miles, which is situated within the western Ventura River Watershed Transverse Ranges (the only major east- west mountain ranges in the continental U.S.). From the upper slopes of the Transverse Ranges, the surface water system in the Ventura River watershed generally flows in a southerly direction to an estuary, located at the mouth of the Ventura River. Groundwater basins composed of alluvial aquifers deposited along the surface water system, are highly interconnected with the surface water system and are quickly recharged or depleted, according to surface flow conditions. Topography in the watershed is rugged and as a result, the surface waters that drain the watershed have very steep gradients, ranging from 40 feet per mile at the mouth to 150 feet per mile at the headwaters. Precipitation varies widely in the watershed. Beneficial Uses in Watershed: Most occurs as rainfall during just a few storms, Estuary Above Estuary between November and Navigation Municipal supply Commercial & sportfishing Industrial service supply March. Summer and fall Estuarine habitat Industrial process supply months are typically dry. Marine habitat Agricultural supply Although snow occurs at Contact & noncontact water recreation Contact & noncontact water recreation higher elevations, Warmwater habitat Warmwater habitat melting snowpack does Wildlife habitat Wildlife habitat not sustain significant Preservation of rare & endangered species Preservation of rare & endangered species Migratory & spawning habitat Migratory & spawning habitat runoff in warmer months. Wetlands habitat Wetlands habitat The erratic weather Shellfish harvesting Coldwater habitat pattern, coupled with the Groundwater recharge steep gradients Freshwater replenishment throughout most of the watershed, result in high flow velocities with most runoff reaching the ocean. The majority of water quality problems involve eutrophication (excessive nutrients and effects), especially in the estuary/lagoon although some DDT and metals have been found in mussel and fish tissue (on the 303(d) list for these). A TMDL is currently scheduled for 2004/05 to address algae problems. A large storm drain enters the river near the estuary and homeless persons live in and frequent the river bed. Sediment in the estuary, however, appears relatively uncontaminated and little sediment toxicity is apparent. In some subwatersheds, high TDS concentrations impair the use of water for agriculture. The 4 watershed's water quality problems are, for the most part, nonpoint The Ventura River Watershed source-related. There have also been incidents of releases of toxic materials into storm drains entering the lower river. • 5 NPDES discharges: one major (POTW) and four discharges covered Water diversions, dams, and groundwater pumping also are thought to by general permits limit surface water resources needed to support a high quality fishery. • 21 dischargers covered under an industrial storm water permit Reduced water supplies affect water quality and thus beneficial uses, • 4 dischargers covered under a particularly with regards to the endangered steelhead trout (steelhead construction storm water permit trout are known to utilize the River and some of its tributaries • Eutrophication concerns, especially in historically supported annual steelhead runs of 5000 – 6000 adults). lagoon Removal of the Matilija Dam (upper river) has recently been identified • Some bioaccumulation of DDT and as a high priority. metals • TDS concerns in some subwatersheds • Impediments to steelhead trout There is only one major discharger, a small POTW (3.0 MGD) in the migration (but much high quality middle reach of the Ventura River which has recently upgraded to habitat) tertiary treatment The treatment plant effluent had been implicated in • More nonpoint source rather than nuisance growth of aquatic plants and low dissolved oxygen found at point source problems times downstream of the discharge. For much of the year, the facility's effluent can make up two-thirds of the total river flow. The most recent monitoring has shown the quality of the effluent has significantly improved with regards to nutrients. DO levels in the river have also improved dramatically and algal growth is greatly reduced below the plant; however, nonpoint sources (agriculture and horse stables) still appear to be contributing to algal growth above the plant. There are four minor NPDES dischargers under general permits and 27 dischargers are enrolled under the general industrial storm water permit in the watershed. Permits in the watershed were targeted for renewal in FY 2000/01. In August 1997, the National Marine Fisheries Service (NMFS) listed the steelhead trout in Southern California as endangered under the Federal Endangered Species Act (ESA). The listing means that any project or action that may affect steelhead trout or their habitats will require consultation with NMFS to obtain an incidental take permit. In order to prepare for the listing and deal with possible regulatory requirements as a result of the listing, the Casitas MWD, City of Ventura, Ventura County Flood Control District, and seven other local public and private agencies collaborated and developed the Ventura River Steelhead Restoration and Recovery Plan in December 1997. The plan also contains large amount of background information on the watershed such as hydrology, biology, steelhead habitat conditions, and the operations and maintenance of water, wastewater, solid waste, transportation and flood control facilities of the sponsoring agencies. The same public agencies have joined together in a cooperative effort to develop a Habitat Conservation Plan (HCP) for their activities in and adjacent to the Ventura River. 5 STATE OF THE WATERSHED Watershed management is an integrated strategy for managing resources. As characteristics and resources vary widely from watershed to watershed, this strategy customizes efforts to manage resources and address problems unique to each watershed. Watershed management can be applied on many different levels, from an overall system for managing resources, restoring and protecting aquatic ecosystems, and protecting human health, to a more focussed effort that addresses one resource, such as water. The scope of the Regional Board's approach is limited to the quality of water resources in the Ventura River watershed.