Water, Groundwater Course. Ground- Coarse. Mid-North Coast Monitoring Summit February 28 th, 2018 Newport, Oregon

Transcription

1 Mid-North Coast Monitoring Summit February 28 th, 2018 Newport, Oregon Coarse Ground- Water, a Groundwater Course with Paige Evans ODEQ & Michael Thoma OWRD 1

2 DEQ s Statewide Groundwater Quality Monitoring Program Present OUTSIDE of existing Groundwater Management Areas (GWMAs)..monitor groundwater for contaminants of concern, including nitrates and pesticides Determine areas of the state that are especially vulnerable to groundwater contamination; status of ambient groundwater quality; long term trends in groundwater quality; emerging groundwater quality problems; and to inform groundwater users of potential risks from contamination 2

3 See New Reports and New Studies here >> ODEQ Groundwater Protection website Reports Written Mid-Rogue Basin 2015 North Coast Basin Reports forthcoming Walla Walla Basin 2016 Mid-Willamette Basin 2017 Planning and Outreach Harney County

4 North Coast Study To access groundwater resources we solicited volunteer well owners We sampled for : Nitrate Arsenic 35 analytes detected Bacteria Nutrients Pesticides (including herbicides) Pharmaceuticals and Personal Care Products Educational Packets and Detailed Laboratory Reports Outside the scope of this study: Hydrogeologic characterization of area Investigation of the sources of contamination Health risk assessments 69 wells sampled 4

5 NITRATE 8 wells had an elevated nitrate concentration (3 mg/l or above) 3 were above the maximum contaminant level of 10 mg/l 5

6 ARSENIC 4 wells with detections (measured as total recoverable arsenic) 2 wells had arsenic concentrations above the maximum contaminant level of 10 μg/l 6

7 BACTERIA Coliform bacteria was detected 54% of wells E. coli was detected in 9 wells 7

8 PESTICIDES Pesticides were detected near most of the populated areas of the study area Three wells had chemicals from more than one parent pesticide detected. PHARMACEUTICALS Sulfamethoxazole, a common antibiotic, was detected in one well sampled during the September sampling period just north of the town of Gearhart, it was not confirmed upon resampling in January

9 10 different pesticiderelated chemicals were detected, representing 8 different parent pesticides The most commonly detected pesticide was 2,6- dichlorobenzamide, a breakdown product of dichlobenil. All pesticide detections were well below their associated screening levels Current Use Pesticides # Wells Detected Max. Conc. Units Screening Level Total Dichlobenils # ng/l 2, ,6-Dichlorobenzamide ng/l 29,000 2 Breakdown product of dichlobenil Dichlobenil ng/l 70,000 2 Herbicide 2,4-D ng/l 70,000 1 Herbicide Desethylatrazine ng/l Not Available Breakdown product of atrazine and simazine Diuron ng/l 2,000 3 Herbicide Imidacloprid ng/l 399,000 2 Insecticide Legacy Pesticides Total DDTs* ng/l ,4 -DDE ng/l Breakdown product of banned insecticide DDT 4,4 -DDD ng/l Breakdown product of banned insecticide DDT gamma-bhc (Lindane) ng/l Banned insecticide Methoxychlor ng/l 40,000 1 Banned insecticide # includes 2,6-Dichlorobenzamide and Dichlobenil *includes 4,4'-DDE and 4,4'-DDD 1 USEPA Maximum Contaminant Level Use 2 USEPA non-regulatory Human Health Benchmark 3 USGS Health-based Screening Level 9

10 MANGANESE 22 wells were above the 50 μg/l secondary drinking water standard (metallic taste and brown or black staining) 3 were above the 300 μg/l Lifetime Health Advisory At high concentrations and extended exposure, manganese has been associated with neurological disease. 10

11 SUMMARY Some chemicals were detected at very low levels. Some contaminants like nitrate, arsenic, bacteria and manganese exceeded health screen levels, more common in the area north of Gearhart. Recommendations Long-term monitoring in the Clatsop Plains area, and north of Gearhart Encourage well owners to test regularly 11

12 Opportunity for Collaboration Outside the scope of this study and report: Hydrogeologic characterization of the study area and contamination 12

13 Hydrogeologic Characterization Provide conceptual groundwater framework of the Mid and North Coast Highlight aquifer types and water use 13

14 Hydrogeologic Characterization Geology of the Coast Subduction zone sea level Coast Range Willamette Valley Cascades Ocean Crust Siletz Terrane Klamath Terrane 14

15 Hydrogeologic Characterization Geology of the Coast Accreted Island Arcs Marine Sediments CRB!? Unconsolidated Material 15

16 Hydrogeologic Characterization Aquifer Classification Bedrock: Fracture-flow High relief, high slopes Low well yield Sediments: pore-flow Plains, bays, floodplains Moderate yields Source: 16

17 Hydrogeologic Characterization Aquifer Classification Bedrock: Fracture-flow High relief, high slopes Low well yield Sediments: pore-flow Plains, bays, floodplains Moderate yields 17

18 Hydrogeologic Characterization Aquifer Classification Clatsop Plains Tillamook Bay Siletz 18

19 Hydrogeologic Characterization Water Use Population centers Municipal and Domestic Agricultural lands 19

20 Hydrogeologic Characterization Conclusions: Geology drives groundwater development High rain + Low yield = Low use Characterization (and collaboration) depends on scale Coarse sampling requires generalizations 20

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22 Hydrogeologic Characterization Observation Wells Very few, based on need and opportunity Stable trends reflect low water use, connection to surface water 22

23 Thank you for listening questions? Paige Evans Natural Resource Specialist Water Quality Monitoring Department of Environmental Quality Laboratory and Environmental Assessment Division Michael Thoma, PhD, RG Hydrogeologist Oregon Water Resource Department