• SECTION 11 Santa Ana Region 2019-2020 Monitoring Annual Report P8/235139 THIS PAGE INTENTIONALLY LEFT BLANK SANTA ANA REGION 2019-2020 Monitoring Annual Report Executive Summary Strawberry Creek SMC Bioassessment Trend Site Monitoring was conducted by the Riverside County Watershed Protection Program during the 2019-2020 monitoring year to address the objectives of the Monitoring and Reporting Program (MRP) of the 2010 Municipal Separate Storm Sewer System (MS4) Permit. This report presents the results of this ninth year of monitoring under the MRP of the 2010 MS4 Permit. The MRP is limited to the area of Riverside County under Permittee jurisdiction within the Santa Ana River Watershed, referred to throughout this report as the Santa Ana Region or SAR. The climate of the SAR is SAR Boundary and Monitoring Sites Mediterranean, characterized by warm, dry summers and cool, rainy winters. Annual precipitation ranges from less than 10 inches in the alluvial valleys to over 36 inches in the mountains. In general, shading from the coastal western boundary of the Santa Ana Mountains translates to very little precipitation throughout valley areas of the inland SAR. Under natural conditions, the majority of streams in the SAR are ephemeral, meaning they are dry and only flowing during and immediately after rain. PERMITTEES EXECUTIVE SUMMARY - SANTA ANA REGION MONITORING ANNUAL REPORT 2019-2020 YEAR 1 MONITORING ANNUAL REPORT Monitoring and Assessment Requirements During the 2019-2020 monitoring year, the SAR Monitoring Program was implemented in accordance with the requirements of the 2010 MS4 Permit. All wet and dry weather monitoring components of the MS4 outfall monitoring program, receiving water monitoring program, and bioassessment monitoring (through participation in the Southern California Stormwater Monitoring Coalition [SMC] regional monitoring program) were completed. In addition, illicit connection/ illegal discharge inspections were conducted, and appropriate illicit discharge detection and elimination procedures were implemented. The Permittees also participated in Total Maximum Daily Load (TMDL) Task Forces, which implemented the monitoring and reporting requirements of the Middle Santa Ana River (MSAR) Bacterial Indicator TMDL and the Lake Elsinore and Canyon Lake Nutrient TMDL. Special studies were also conducted to address specific research or management actions that are not addressed by the Permit-prescribed monitoring program. Summary of the 2019-2020 SAR Monitoring Program Monitoring Monitoring No. Stations Completed? Program Component Sampling Frequency MS4 Outfall MS4 Outfall 2 Dry Events, 3 Wet Events 7 Stations Monitoring Monitoring ? Dry weather, scheduled and monitored per Permittee IC/ID Monitoring IC/ID Investigations Local Implementation Plan ? Receiving Water 2 Dry Events, 2 Wet Events* 3 Stations (1 wet only, 1 Monitoring dry only, 1 wet and dry) ? Water Column 2 Dry Events, 2 Wet Events 3 Stations Toxicity Receiving Water ? Monitoring Follow-up Toxicity Sampling as necessary Analyses ? SMC Bioassessment 1 Dry Event (2020) 2 Condition, 2 Trend Monitoring Program Sites ? TMDL/ 303(d) Listed Waterbody Monitoring -MSAR Bacterial Indicator TMDL Monitoring -Lake Elsinore and Canyon Lake Nutrient TMDL Monitoring Special Studies Regional Monitoring Programs ? -SMC LID BMP Special Study -Hydromodification Monitoring Program -Salinity Management Program Post-Fire Monitoring Studies MSAR - Middle Santa Ana River, LID - Low Impact Development, BMP - Best Management Practices *During the 2019-2020 monitoring year, an additional wet weather event was sampled for chemistry at one receiving water station. EXECUTIVE SUMMARY - SANTA ANA REGION MONITORING ANNUAL REPORT 2019-2020 YEAR 2 MONITORING ANNUAL REPORT Assessment and Reporting The 2019-2020 monitoring year water quality data, in conjunction with historical monitoring results, were used to evaluate the status and trends of conditions in receiving waters and discharges from the MS4 that may impact beneficial uses of receiving waters in the SAR. Water quality sampling results were compared to Basin Plan water quality objectives (WQOs), California Toxics Rule WQOs, and standards from the Statewide Bacteria Provisions ? statistical threshold values (STVs) or TMDL numeric targets for E. coli, as applicable. Sample results from MS4 outfall stations were compared to these receiving water WQO criteria for comparison purposes only. Large and/ or high intensity precipitation is needed to generate flow in ephemeral receiving waters. If a site was dry or flow was insufficient for sample collection, dry weather events were classified as visited, not Santa Ana River sampled (VNS). Data Assessment Overview 7 Core Outfalls - Comparison to WQOs 3 Receiving Water Stations - Trend Analysis - Persistence Analysis - Frequency Analysis - Land Use and Sources Evaluation - Model Monitoring Program Management Questions EXECUTIVE SUMMARY - SANTA ANA REGION MONITORING ANNUAL REPORT 2019-2020 YEAR 3 MONITORING ANNUAL REPORT Wet Weather Monitoring Results Summary - MS4 outfall data were more frequently above WQOs than receiving water station data. MS4 discharges are not required to meet WQOs, which are applicable to receiving water data only for compliance. - E. coli was above receiving water WQOs during at least one wet weather event at six MS4 outfall stations and the Perris Valley Channel at Nuevo Road receiving water station. - Dissolved copper concentrations were above receiving water WQOs during at least one wet weather event at all seven MS4 outfall stations and the Temescal Channel at Main receiving water station. - pH was outside of the Basin Plan WQO range at five MS4 outfall stations (one event each) but in range at receiving water stations. - Total nitrogen exceeded at two MS4 outfall stations (one event each) Wet weather conditions at the Magnolia Center Outfall and also once at Temescal Channel at Main receiving water station. Spatial Overview of 2019-2020 Wet Weather Monitoring Results Only parameters with concentrations exceeding receiving water WQOs are shown below. For these parameters, statistically significant long-term trends and results that persistently exceed WQOs are also presented as symbols on the map. Trends varied among parameters and stations. While dissolved copper was above WQOs, total copper concentrations were found to be decreasing at two MS4 outfalls and the Temescal Channel at Main receiving water station. EXECUTIVE SUMMARY - SANTA ANA REGION MONITORING ANNUAL REPORT 2019-2020 YEAR 4 Progress Toward Numeric Goals MONITORING ANNUAL REPORT Dry Weather Monitoring Summary - Three of the seven MS4 outfall stations and one receiving water station were VNS during dry weather monitoring events. Perris Line J Outfall - E. coli was below the WQO at the one receiving water station where dry weather samples were collected. - Dissolved copper was below the WQO at all MS4 outfalls and the sampled receiving water station during dry weather. - Chronic toxicity to P. subcapitata growth was observed in both dry weather samples at Santa Ana River at Highgrove. - Nitrogen-Nutrients met WQOs during dry weather at all MS4 outfall and receiving water stations, where applicable, except total nitrogen during a single dry weather event at the North Norco Outfall. - 4,4' DDT had slight exceedances of the receiving water WQO at three of the four outfalls sampled in dry weather. - Nitrate showed a decreasing trend at Santa Ana River at Highgrove and two MS4 outfall stations, although total organic nitrogen was increasing and dissolved oxygen decreasing at the two outfalls. - E. coli concentrations showed an increasing trend at Magnolia Center Outfall and University Wash Channel. Total and dissolved copper were found to be increasing at Santa Ana River at Highgrove. Frequency of VNS Results at SAR MS4 Outfall Stations During the 2010 MS4 Permit term, VNS results have been frequent during dry weather events as shown in the figure below that illustrates in orange the proportion of outfalls that were VNS during each year. During the 2019-2020 monitoring year, three of the seven MS4 outfall stations were reported as VNS during both dry weather events. These same three MS4 stations have been VNS for all dry weather monitoring activities conducted in accordance with the 2010 MS4 Permit. Two additional outfalls that are historically VNS were sampled during the 2019-2020 year, due to a flowing lateral from one outfall and a changed flow regime at the other outfall (resulting from sediment buildup within the storm drain). EXECUTIVE SUMMARY - SANTA ANA REGION MONITORING ANNUAL REPORT 2019-2020 YEAR 5 Progress Toward Numeric Goals MONITORING ANNUAL REPORT Bioassessment Monitoring Results The bioassessment component of the receiving water monitoring program was fulfilled through District participation, on behalf of the Permittees, in the SMC Regional Watershed Monitoring Program (RWMP). Bioassessment monitoring was conducted at two condition sites and two long-term trend sites in June 2020 within the SAR, which has a large number of engineered and modified flood control channels. - At the Strawberry Creek trend site, the California Stream Condition Index (CSCI) benthic health score was in the likely intact range during the 2020 survey. The California Rapid Assessment Method (CRAM) score indicated fair physical habitat quality. No significant trend was identified at Strawberry Creek based on 2015-2020 CSCI scores. - At the Cucamonga Channel trend site, a fully hardened ? engineered channel,