The monitoring program targets the three specific types of waterbodies listed below.

Land Use Site (Discharge Characterization) Monitoring
Land use monitoring is designed to capture stormwater discharge from a specific type of land use. In theStormwater Management Plan, sites are chosen to represent three land use types: agricultural, industrial, and residential. Land use monitoring began during the 1992-93 monitoring season and is designed to characterize stormwater discharges from the three specific land uses noted above. During the 2005/06 monitoring season, samples from an October 2005 wet weather event were collected for water chemistry and aquatic toxicity at the agricultural monitoring site at Wood Road (A-1 map data). During the same wet weather event, only aquatic toxicity grab samples were collected at the Ortega Street (I-2 map data) and Swan Street (R-1 map data) Land Use sites because the Stormwater Monitoring Program had already satisfied its NPDES permit condition stating that these two Land Use sites must be monitored a minimum of three times per permit term with respect to the collection of water chemistry samples. However, the Stormwater Monitoring Program is still under a regulatory obligation to collect aquatic toxicity grab samples at these sites in order to amass baseline toxicity information related to land use discharges.

Receiving Water (Tributaries) Monitoring
Receiving water monitoring is designed to characterize the quality of receiving waters rather than discharges to the receiving waters. This type of monitoring evaluates the water quality of smaller waterbodies tributary to main river systems. Monitoring smaller tributaries allows the Stormwater Monitoring Program to focus on smaller sub-basins of the watershed that are not impacted by discharges from wastewater treatment facilities. Monitoring a localized section of the watershed allows the Stormwater Monitoring Program to better examine the impact of stormwater on the watershed than mass emission monitoring (see discussion below). During the 2005/06 monitoring season, the Receiving Water sites La Vista (W-3 map data) and Revolon Slough (W-4 map data) were monitored once in October 2005 under wet weather conditions. Water chemistry and aquatic toxicity samples were collected at both sites. Receiving water monitoring at these sites was first implemented during the 1997-98 season and captures stormwater runoff from the Revolon Slough sub-basin.

Mass Emission Monitoring
The purpose of mass emission monitoring is to identify pollutant loads to the ocean and identify long- term trends in pollutant concentrations. Mass Emissionsites are located in the lower reaches of major watersheds. Through water quality monitoring at these sites, the Stormwater Monitoring Program can evaluate the cumulative effects of stormwater and other surface water discharges on beneficial uses in the watershed prior to discharge to the ocean. Both Mass Emission and Receiving Water stations allow for the measurement of water quality conditions in a surface water body, whereas Land Use monitoring stations permit the water quality characterization of discharges to surface waterbodies. Mass Emission monitoring stations allow for the measurement of water quality parameter concentrations resulting from discharges throughout an entire watershed. The Mass Emission drainage areas are much larger than the drainage areas associated with Receiving Water sites, and include other sources of discharge, such as wastewater treatment plants, non-point sources, and groundwater discharges.

Mass Emission stations are located in the three major Ventura County watersheds: Calleguas Creek (ME-CC map data), Ventura River (ME-VR2 map data), and Santa Clara River (ME-SCR map data). Each Mass Emission station was monitored this season. Water quality samples from four wet weather events were collected for water chemistry at the Mass Emission sites, while aquatic toxicity samples were collected at each site during Events 1 (October 2005) and 2 (November 2005). As required by the permit, additional dry weather events are scheduled for later in the current monitoring season. Results from these dry weather monitoring events will be included in the October 2006 Annual Monitoring Report. Monitoring at the ME-CC station was initiated during the 2000/01 monitoring season, monitoring at the ME-SCR station was initiated during the 2001/02 monitoring season, and monitoring at the newly installed ME-VR2 station was initiated during the 2004/05 monitoring season after landslide activity at the original Ventura River Mass Emission station, ME-VR (map data), precluded further sampling at that location.