Historical Seawater Intrusion Map Pressure 180-Foot Aquifer - 500 mg/L or Greater Chloride Areas

Monterey County Water Resources Agency (MCWRA) | April 11th, 2018

History and Sources of Co-Occurring Pesticides in an Abstraction Well Unraveled by Age Distributions of Depth-Specific Groundwater Samples

American Chemical Society (ACS) | November 24th, 2019

When groundwater-based drinking water supply becomes contaminated, the timing and source of contamination are obvious questions. However, contaminants often have diffuse

When groundwater-based drinking water supply becomes contaminated, the timing and source of contamination are obvious questions. However, contaminants often have diffuse sources and different contaminants may have different sources even in a single groundwater well, making these questions complicated to answer. Age dating of groundwater has been used to reconstruct contaminant travel times to wells; however, critics have highlighted that groundwater flow is often complex with mixing of groundwater of different ages. In drinking water wells, where water is typically abstracted from a large depth interval, such mixing is even more problematic. We present a way to overcome some of the obstacles in identifying the source and age of contaminants in drinking water wells by combining depth-specific sampling with age tracer modeling, particle tracking simulations, geological characterization, and contaminant properties. This multitool approach was applied to a drinking water well, where bentazon and dichlorprop contamination was found to have different pollutant sources and release histories, even though both pesticides can be associated with the same land use. Bentazon was derived from recent application to a golf course, while dichlorprop was derived from agricultural use more than 30 years ago. The advantages, limitations, and pitfalls of the proposed course of action are then further discussed.

History and Sources of Co-Occurring Pesticides in an Abstraction Well Unraveled by Age Distributions of Depth-Specific Groundwater Samples

American Chemical Society (ACS) | November 24th, 2019

When groundwater-based drinking water supply becomes contaminated, the timing and source of contamination are obvious questions. However, contaminants often have diffuse

When groundwater-based drinking water supply becomes contaminated, the timing and source of contamination are obvious questions. However, contaminants often have diffuse sources and different contaminants may have different sources even in a single groundwater well, making these questions complicated to answer. Age dating of groundwater has been used to reconstruct contaminant travel times to wells; however, critics have highlighted that groundwater flow is often complex with mixing of groundwater of different ages. In drinking water wells, where water is typically abstracted from a large depth interval, such mixing is even more problematic. We present a way to overcome some of the obstacles in identifying the source and age of contaminants in drinking water wells by combining depth-specific sampling with age tracer modeling, particle tracking simulations, geological characterization, and contaminant properties. This multitool approach was applied to a drinking water well, where bentazon and dichlorprop contamination was found to have different pollutant sources and release histories, even though both pesticides can be associated with the same land use. Bentazon was derived from recent application to a golf course, while dichlorprop was derived from agricultural use more than 30 years ago. The advantages, limitations, and pitfalls of the proposed course of action are then further discussed.

Hoopa Valley Tribe Water Quality Plan

Hoopa Valley Tribal Environmental Protection Agency | February 14th, 2008

The Hoopa Valley Tribal Council pursuant to Title 37 of the Hoopa Tribal Code has assigned the primary responsibility for the protection and enhancement of water quality

The Hoopa Valley Tribal Council pursuant to Title 37 of the Hoopa Tribal Code has assigned the primary responsibility for the protection and enhancement of water quality on the Hoopa Valley Indian Reservation to the Riparian Review Committee (RRC). The RRC along with the Hoopa Valley Tribal Environmental Protection Agency provides Reservation-wide coordination of the water quality control program by developing, reviewing and recommending for Tribal approval Reservation wide policies and plans for the implementation of Tribal and Federal law. This Water Quality Control Plan recognizes the unique characteristics of each watershed with regard to natural water quality, existing, potential, and historical beneficial uses, and water quality problems. The goal of this plan is to provide a definitive program of actions designed to preserve and enhance water quality on the Reservation, and to protect the beneficial uses of water for the next 10 years to 20 years. The plan is concerned with all factors and activities that might affect water quality. However, the plan emphasizes actions to be taken by the Riparian Review Committee, the Hoopa Valley Tribal Fisheries, Forestry, Public Utility Departments, and Tribal Environmental Protection Agency, as they have responsibility for maintaining water quality on the Reservation. The Water Quality Control Plan (WQCP) is comprehensive in scope. The WQCP describes the Hoopa Valley Reservation waters, the quality and quantity issues, and the existing, potential and historical beneficial uses of the Reservation’s waters. The plan also prescribes criteria for the protection of the Reservation waters and includes plans and policies that describe the basis for the management of water quality and protection of human health. The Hoopa Valley Tribe has recognized authority for setting water quality standards for its Reservation waters, including both the Trinity and Klamath Rivers (U.S. EPA, 2002). Included in the plan are specific criteria that apply to the Lower Klamath River on the Hoopa Valley Reservation (Figure 1.1).

How freeing rivers can help California ease flood risks and revive ecosystems

Los Angeles Times | February 20th, 2024

Natural floodplains — the lush green lands along rivers that historically flooded, retained water, and nourished life in the heart of the valley — were mostly drained

Natural floodplains — the lush green lands along rivers that historically flooded, retained water, and nourished life in the heart of the valley — were mostly drained and converted to farmland generations ago as the state’s waters were dammed and diverted. Today, an effort to bring back some of those floodplains is flourishing at the 2,100-acre Dos Rios Ranch Preserve near Modesto, where workers years ago planted native trees on retired farm fields and removed berms to create space for water to spread out again.

Human Impacts Dominate Global Loss of Lake Ecosystem Resilience

American Geophysical Union (AGU) | June 5th, 2024

Hydraulic Fracturing and Water Resources: Separating the Frack from the Fiction

Pacific Institute | June 21st, 2012

Hydraulic fracturing, or “fracking,” has generated growing controversy in the past few years. New research from the Pacific Institute finds the real issues around its

Hydraulic fracturing, or “fracking,” has generated growing controversy in the past few years. New research from the Pacific Institute finds the real issues around its impacts on water are shared by stakeholders from government to industry to environmental groups – and point to the need for better and more transparent information in order to clearly assess the key water-related risks and develop sound policies to minimize those risks. Much of the public attention on hydraulic fracturing has centered on the use of chemicals in the fracturing fluids and the risk of groundwater contamination. But the new study finds that while chemical disclosure can be useful for tracking contamination, risks associated with fracking chemicals are not the only issues that must be addressed. The massive water requirements for fracking and the potential conflicts with other water needs, including for agriculture and for ecosystems, pose major challenges. Methane contamination of drinking water wells is also a concern according to some field studies, as are the serious challenges associated with storing, transporting, treating, and disposing of wastewater. The report Hydraulic Fracturing and Water Resources: Separating the Frack from the Fiction is a detailed assessment and synthesis of existing research on fracking as well as the results of interviews with representatives from state and federal agencies, industry, academia, environmental groups, and community-based organizations from across the United States. Interviewees identified a broad set of social, economic, and environmental concerns, foremost among which are impacts of hydraulic fracturing on the availability and quality of water resources. “Despite the diversity of viewpoints among the stakeholders interviewed, there was surprising agreement about the range of concerns associated with hydraulic fracturing. Among the most commonly cited were concerns about spills and leaks, wastewater management, and water withdrawals,” said Heather Cooley, co-director of the Pacific Institute Water Program. “In addition to concerns about impacts on water resources, social and economic concerns were identified as well, such as worker health and safety and community impacts associated with rapidly industrializing rural environments.”

Hydraulic fracturing in faulted sedimentary basins: Numerical simulation of potential contamination of shallow aquifers over long time scales

American Geophysical Union (AGU) | December 12th, 2013

Hydraulic fracturing, used to economically produce natural gas from shale formations, has raised environmental concerns. The objective of this study is to assess one of

Hydraulic fracturing, used to economically produce natural gas from shale formations, has raised environmental concerns. The objective of this study is to assess one of the largely unexamined issues, which is the potential for slow contamination of shallow groundwater due to hydraulic fracturing at depth via fluid migration along conductive faults. We compiled publicly available data of shale gas basins and hydraulic fracturing operations to develop a two-dimensional, single-phase, multi-species, density-dependent, finite-element numerical groundwater flow and mass transport model. The model simulates hydraulic fracturing in the vicinity of a permeable fault zone in a generic, low-recharge, regional sedimentary basin in which shallow, active groundwater flow occurs above nearly stagnant brine. A sensitivity analysis of contaminant migration along the fault considered basin, fault and hydraulic fracturing parameters. Results show that specific conditions are needed for the slow contamination of a shallow aquifer: a high permeability fault, high over-pressure in the shale unit, and hydro-fracturing in the upper portion of the shale near the fault. Undersuch conditions, contaminants from the shale unit reach the shallow aquifer in less than 1000 years following hydraulic fracturing, at concentrations of solutes up to 90% of their initial concentration in the shale, indicating that the impact on groundwater quality could be significant. Important implications of this result are that hydraulic fracturing should not be carried out near potentially conductive faults, and that impacts should be monitored for long timespans. Further work is needed to assess the impact of multiphase flow on contaminant transport along natural preferential pathways.

Hydrodynamic and Water Quality Model Calibration and Application in San Francisco Bay

San Francisco Estuary Institute (SFEI) | September 3rd, 2018

To answer management questions about nutrient related water quality in San Francisco Bay, hydrodynamic and biogeochemical models have been developed. This report outline

To answer management questions about nutrient related water quality in San Francisco Bay, hydrodynamic and biogeochemical models have been developed. This report outlines the development of both of these models. Section 2 is the description and validation of the hydrodynamic model, previously completed in December 2017 for the San Francisco Bay Interim Model Validation Report, but included here for completeness. Section 3 of this report covers the description and validation the biogeochemical model.

Hydrodynamic Model Development Report: Sacramento-San Joaquin River Delta and Suisun Bay (Water Year 2016)

San Francisco Estuary Institute (SFEI) | December 13th, 2019

This report describes work related to hydrodynamic model development for the San Francisco Bay-Delta Estuary, undertaken as part of a broader eort to develop and apply co

This report describes work related to hydrodynamic model development for the San Francisco Bay-Delta Estuary, undertaken as part of a broader eort to develop and apply coupled biogeochemical-hydrodynamic models to inform nutrient management decisions. The primary intended application of the hydrodynamic model output is for use as input to an offline coupled biogeochemical model to simulate a wide range of state variables and processes, including: advective and dispersive transport, nutrient transformations, phytoplankton production, benthic and pelagic grazing, sediment diagenesis, and oxygen cycling.