Status and understanding of groundwater quality in the Northern Coast Ranges study unit, 2009: California GAMA Priority Basin Project

Mathany, Timothy M.; Belitz, Kenneth

doi:10.3133/sir20145215

Cited by 2 publications

(5 citation statements)

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“…Although oxic conditions generally prevail in California groundwater due to the climate, anoxic conditions do occur: there are 14 study areas in which the areal proportion for manganese exceeds 10% (Table S4c2, SI). The 14 study areas are distributed across seven hydrogeologic provinces, and additional discussion is provided in several USGS SIRs. − ,, …”

Section: Resultsmentioning

confidence: 99%

“…The 14 study areas are distributed across seven hydrogeologic provinces, and additional discussion is provided in several USGS SIRs. [49][50][51][52][53][54]57,58 High concentrations of uranium in California groundwater are associated with granitic rocks and alluvium derived from granitic rocks. In the eastern SJV, uranium also has been mobilized by downward-moving irrigation water with elevated bicarbonate concentrations.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

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Metrics for Assessing the Quality of Groundwater Used for Public Supply, CA, USA: Equivalent-Population and Area

Belitz

Fram

Johnson

2015

Environ. Sci. Technol.

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Data from 11,000 public supply wells in 87 study areas were used to assess the quality of nearly all of the groundwater used for public supply in California. Two metrics were developed for quantifying groundwater quality: area with high concentrations (km(2) or proportion) and equivalent-population relying upon groundwater with high concentrations (number of people or proportion). Concentrations are considered high if they are above a human-health benchmark. When expressed as proportions, the metrics are area-weighted and population-weighted detection frequencies. On a statewide-scale, about 20% of the groundwater used for public supply has high concentrations for one or more constituents (23% by area and 18% by equivalent-population). On the basis of both area and equivalent-population, trace elements are more prevalent at high concentrations than either nitrate or organic compounds at the statewide-scale, in eight of nine hydrogeologic provinces, and in about three-quarters of the study areas. At a statewide-scale, nitrate is more prevalent than organic compounds based on area, but not on the basis of equivalent-population. The approach developed for this paper, unlike many studies, recognizes the importance of appropriately weighting information when changing scales, and is broadly applicable to other areas.

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Section: Resultsmentioning

confidence: 99%

Section: Environmental Science and Technologymentioning

confidence: 99%

Metrics for Assessing the Quality of Groundwater Used for Public Supply, CA, USA: Equivalent-Population and Area

Belitz

Fram

Johnson

2015

Environ. Sci. Technol.

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“…All of the high concentrations of boron and most of the moderate concentrations occurred in the NOCO-IN study area. High and moderate concentrations of boron were associated with elevated groundwater temperatures, groundwater chemistry characteristics similar to those of geothermal waters, and proximity to known geothermal areas, suggesting that a likely source of the boron was groundwater interaction with hydrothermal systems in the NOCO-IN study area (Mathany and Belitz, 2015). Previous investigations in the Geysers-Clear Lake area (and surrounding areas) by the U.S. Geological Survey and others have identified elevated water temperatures, high concentrations of boron, arsenic, and lithium, and elevated helium isotope ratios as the most common chemical signatures of hydrothermal system interaction (Donnelly-Nolan and others, 1993;Goff and others, 1993;Peters, 1993;Forrest and others, 2013).…”

Section: High Moderate and Low Concentrations Are Defined Relative To...mentioning

confidence: 98%

“…The Northern Coast Ranges (NOCO) study unit is 633 square miles and consists of 35 groundwater basins and subbasins (California Department of Water Resources, 2003;Mathany and Belitz, 2015). These basins and subbasins were grouped into two study areas based primarily on locality.…”

Section: The Northern Coast Ranges Study Unitmentioning

confidence: 99%

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Groundwater quality in the Northern Coast Ranges Basins, California

Mathany¹,

Belitz²

2015

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Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project (PBP) of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. The basins in the Coast Ranges of northern California constitute one of the study units being evaluated. The Northern Coast Ranges Study UnitThe Northern Coast Ranges (NOCO) study unit is 633 square miles and consists of 35 groundwater basins and subbasins (California Department of Water Resources, 2003;Mathany and Belitz, 2015). These basins and subbasins were grouped into two study areas based primarily on locality. The groundwater basins and subbasins located inland, not adjacent to the Pacific Ocean, were aggregated into the Interior Basins (NOCO-IN) study area. The groundwater basins and subbasins adjacent to the Pacific Ocean were aggregated into the Coastal Basins (NOCO-CO) study area (Mathany and others, 2011). The primary aquifer system in the NOCO-IN study area occurs in alluvial basins made up of sand, silt, gravel, clay, and thin volcanic ash layers or lenses. Groundwater movement in the NOCO-IN study area follows the topography and direction of surfacewater features. In the NOCO-CO study area, groundwater is present in alluvial fan, floodplain, and terrace deposits. Groundwater movement in the NOCO-CO study area is from east to west towards the Pacific Ocean. The primary aquifer system in the study unit generally is defined as those parts of the aquifer system corresponding to the perforated intervals of sites listed in the California Department of Public Health (CDPH) database of public drinking-water supply sources. Well depths in the NOCO-IN study area ranged from 36 to 400 feet below land surface (ft bls), and depths to top-of-perforations ranged from 15 to 148 ft bls. In the NOCO-CO study area, well depths ranged from 15 to 400 ft bls, and depths to top-of-perforations ranged from 10 to 356 ft bls. Water quality in the primary aquifer system may differ from that in the shallower and deeper parts of the aquifer system.Average annual rainfall in the NOCO study unit ranges from 22 to 79 inches. In the NOCO-IN study area, the climate is classified as Mediterranean, with warm to hot, dry summers and cold, wet winters. In the NOCO-CO study area, the climate is influenced by the Pacific Ocean and is characterized by cool to mild summers and cold, wet winters. The study unit is drained by several rivers and their principal tributaries: the Eel, Russian, Mad, Navarro, Smith, Klamath, Noyo, and Big Rivers.Land use in the study unit is about 60 percent (%) natural (mostly grassland and forest), 29% agricultural, and 11% urban. The primary uses of agricultural lands are pasture, row crops, hay, vineyards, and timberlands. The largest urban areas are the cities of Crescent City, Arcata, Eureka, Fort Bragg, Willits, Ukiah, a...

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Status and understanding of groundwater quality in the Northern Coast Ranges study unit, 2009: California GAMA Priority Basin Project

Cited by 2 publications

References 21 publications

Metrics for Assessing the Quality of Groundwater Used for Public Supply, CA, USA: Equivalent-Population and Area

Metrics for Assessing the Quality of Groundwater Used for Public Supply, CA, USA: Equivalent-Population and Area

Groundwater quality in the Northern Coast Ranges Basins, California

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