Protect water quality at public drinking water wells (nitrate and TDS) and irrigation. El Rio #15 NO3 NO3 BMO El Rio #15 TDS TDS BMO.

Transcription

1 OXNARD PLAIN FOREBAY OXNARD PLAIN FOREBAY Protect water quality at public drinking water wells (nitrate and TDS) and irrigation suitability (TDS). (Note TDS = total dissolved solids) Nitrate Concentration: 22.5 mg/l NO 3 (5% of State of California MCL) El Rio #5 NO3 NO3 BMO El Rio #5 TDS TDS Concentration: 1,2 mg/l (LARWQCB Basin Plan Objective) 12 1,5 In 214, average nitrate concentrations were above the BMO at well El Rio #5 and at well El Rio #15. Average TDS concentrations were above the BMO at well El Rio #5 yet below the BMO at well El Rio #15. Declining water levels during 214 have contributed to increasing nitrate and TDS concentrations, compared to those in 213. State Well Number Depth Nitrate (mg/l) 5 yr Trend (ft) BMO 214 Ave BMO 214 Ave Nitrate TDS 2N22W23B2S (El Rio #5) ,2 1,338 2N22W23C5S (El Rio #15) ,2 1, , J 9 J 95 J J 5 J 1 J 15 El Rio #15 NO3 NO3 BMO El Rio #15 TDS 5 1,5 El Rio #15 El Rio #5 4 1, J 9 J 95 J J 5 J 1 J 15 Item 4A - Page 1 of 6

2 OXNARD PLAIN UPPER AQUIFER SYSTEM 214 OXNARD PLAIN UPPER AQUIFER SYSTEM 214 Prevent saline intrusion in the Oxnard and Mugu Aquifers. Primary source is seawater inflow via aquifer outcrops in submarine canyons near Port Hueneme and Pt. Mugu. Water Levels: Average groundwater elevations suffient to maintain slight seaward groundwater gradient. Elevation varies with location. Chloride Concentration: 15 mg/l Chloride (LARWQCB Basin Plan Objective). Water level BMOs were not met in 214. A comparison of water levels indicates that water levels have declined at all nine monitoring locations over the past three years. Chloride BMOs were met at approximately 4% of the monitoring locations. Consistent with past results, chloride BMOs were not met near Port Hueneme (CM4) and Pt. Mugu (CM6 and CM1A) CM3 145 WL CM3 145 CL A1 195 WL A1 32 WL A1 195 CL A1 32 CL 5, 4, 3, 2, 1, State Well Number 1N23W1C5S (CM3 145) 1N22W2J8S (A1 195) 1N22W2J7S (A1 32) 1N22W28G5S (CM4 2) 1N22W28G4S (CM4 275) 1N21W19L12S (SCE 22) 1S22W1H4S (CM6 2) 1S22W1H3S (CM6 33) 1S21W8L4S (CM1A 22) Depth Water Level (ft msl) 5 yr Trend (ft) BMO 214 Ave BMO 214 Ave Water Level Chloride , , , ,4 1 J 9 J 95 J J 5 J 1 J CM4 2 WL CM4 275 WL CM4 2 CL CM4 275 CL 1, 8, 6, 4, 2, 2 J 9 J 95 J J 5 J 1 J 15 SCE 22 WL SCE 22 CL J 9 J 95 J J 5 J 1 J 15 3 J 9 J 95 J J 5 J 1 J 15 1 CM6 2 WL CM6 33 WL CM6 2 CL CM6 33 CL 5, 5 CM1A 22 WL CM1A 22 CL 2, CM3 4, 16, A1 CM4 SCE , 2, 1, , 8, 4, CM6 CM1A 4 J 9 J 95 J J 5 J 1 J 15 2 J 9 J 95 J J 5 J 1 J 15 Item 4A - Page 2 of 6

3 OXNARD PLAIN LOWER AQUIFER SYSTEM OXNARD PLAIN LOWER AQUIFER SYSTEM Prevent saline intrusion in the LAS. Sources are seawater inflow via aquifer outcrops in submarine canyons near Port Hueneme and Pt. Mugu and marine sediments. Water Levels: Average groundwater elevations suffient to maintain slight seaward groundwater gradient. Elevation varies with location. Chloride Concentration: 15 mg/l Chloride (LARWQCB Basin Plan Objective). In 214, water level BMOs were not met. Average water level at inland PTP #1 location was below its respective BMO by 133 feet. As long as water levels remain depressed, the potential for saline intrusion remains. Consistent with the past, chloride BMOs were not met near Port Hueneme (CM2) and Pt. Mugu (CM1A) (areas of documented seawater intrusion). State Well Number Depth Water Level (ft msl) 5 yr Trend (ft) BMO 214 Ave BMO 214 Ave Water Level Chloride 1N23W1C4S (CM3 695) N22W29D2S (CM2 76) ,85 1S22W1H1S (CM6 55) S21W8L3S (CM1A 565) ,13 1N21W7J2S (PTP #1) CM3 695 WL CM3 695 CL 4 J 9 J 95 J J 5 J 1 J 15 CM6 55 WL CM6 55 CL 2 1, 1 9, 8, 1 7, 2 6, 3 5, 4 4, 5 6 3, 7 2, 8 1, 9 J 9 J 95 J J 5 J 1 J J 9 J 95 J J 5 J 1 J CM2 76 WL CM2 76 CL CM1A 565 WL CM1A 565 CL J 9 J 95 J J 5 J 1 J 15 12, 9, 6, 3, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, CM3 CM 2 CM6 PTP 1 CM1A PTP #1 WL PTP #1 CL J 9 J 95 J J 5 J 1 J Item 4A - Page 3 of 6

4 State Well Number 1N21W3K1S (PV #4) 1N21W21H2S (PV #1) PLEASANT VALLEY BASIN PLEASANT VALLEY BASIN Prevent inland migration of saline groundwater from coastal areas, underlying sources, and fine grained interbeds. Water Levels: Average groundwater elevations suffient to prevent landward migration from coastal areas and minimize vertical gradients. Chloride Concentration: 15 mg/l Chloride (LARWQCB Basin Plan Objective). In 214, water level BMOs were not met at either location. Water levels have fluctuated annually yet the overall waterlevels have declined during the last 3 of the last 5 years, remaining significantly below the BMOs. The chloride BMO is met at both monitoring locations. Over the past 5 years, the chloride concentrations at both monitoring locations have fluctuated, yet are within the range of fluctuation. Depth Water Level (ft msl) 5 yr Trend (ft) BMO 214 Ave BMO 214 Ave Water Level Chloride PV #4 WL PV #4 CL J 9 J 95 J J 5 J 1 J 15 PV #1 WL PV #1 CL 2 28 PV # PV # J 9 J 95 J J 5 J 1 J 15 Item 4A - Page 4 of 6

5 ARROYO SANTA ROSA BASIN ARROYO SANTA ROSA BASIN Meet LARWQCB Basin Plan Objectives for nitrate and chloride. Nitrate Concentration: 45 mg/l NO 3 (LARWQCB Basin Plan Objective & State of CA MCL) 25C5S NO3 NO3 BMO 25C5S CL Chloride Concentration: 15 mg/l (LARWQCB Basin Plan Objective) Based on the availble data, only one of the four BMOs was met in 214. For the water quality sample collected from 25C5, the Nitrate concentration was just below its BMO (43 vs. 45 mg/l) and the chloride concentration was above the BMO (181 vs. 15 mg/l). For the water quality sample collected from 25D1, both the nitrate and chloride concentrations exceeded their BMOs 9 vs. 45 mg/l and 159 vs. 15 mg/l, repectively. Over the past 5 years: nitrate concentrations declined in well 25C1 and increased in well 25D1; and chloride concentrations have increased. State Well Number Depth Nitrate (mg/l) 5 yr Trend * (ft) BMO 214 Ave BMO 214 Ave Nitrate Chloride 2N2W25C5S N2W25D1S Unknown J 9 J 95 J J 5 J 1 J 15 25D1S NO3 NO3 BMO 25D1S CL 25C D J 9 J 95 J J 5 J 1 J 15 Item 4A - Page 5 of 6

6 LAS POSAS BASINS LAS POSAS BASINS Maintain chloride and TDS concentrations suitable for irrigation of salt sensitive crops, particulary avocados and berries. BMOs for SLP are equal to the concentrations observed in surface water in Arroyo Las Posas. Chloride Concentration: WLP & ELP: 1 mg/l; SLP: 16 mg/l. TDS Concentration: ELP: 5 mg/l; WLP: 6 mg/l; and SLP: 1,5 mg/l. BMO monitoring locations 1E1 and 6N3 have been replaced with 1E2 and 7D2 respectively. No data is available for BMO monitoring location 6R1 for 214 (well being repaired). In the ELP Basin the chloride BMO is being met at only one monitoring location, and the is not being met. In the WLP Basin, both BMOs are being met at the one monitoing station. In the SLP Basin, the chloride BMO is being met, while the is not being met. The general five year trend in the Las Posas basins is rising chloride and TDS concentrations. State Well Number Depth 5 yr Trend (ft) BMO 214 Ave BMO 214 Ave Chloride TDS 2N2W9F1S (ELP) 96 1, ,51 2N2W9R1S (ELP) ,51 2N2W1E2S (ELP) Replacement 68 1, N2W6R1S (WLP) 1,9 1,512 1 No Data 6 No Data Insufficient Data 2N2W8F1S (WLP) 752 1, N19W7D2S (SLP) Replacement , F1 CL 9F1 TDS J 9 J 95 J J 5 J 1 J 15 2, 1,6 1, E1 CL 1E2 CL 1E1 TDS 1E2 TDS 2, Well 1E1 Destroyed 9/6/213 under permit. Replacement is 1E2. 1,6 1, J 9 J 95 J J 5 J 1 J R1 CL 9R1 TDS 6R1S CL 6R1S TDS Water quality to be tested in , 1,6 1, , 1,6 1, of 1 6R1 8F1 9F1 9R1 1E2 7D2 J 9 J 95 J J 5 J 1 J 15 8F1 CL 8F1 TDS 25 2, J 9 J 95 J J 5 J 1 J 15 6N3 CL 7D2 CL 6N3 TDS 7D2 TDS 25 2, 2 1,6 2 1, , Well 6N3 has been abandoned with last data BMO replacement 7D2. Data shown starting 29 1,2 8 4 J 9 J 95 J J 5 J 1 J 15 J 9 J 95 J J 5 J 1 J 15 Item 4A - Page 6 of 6