Microplastics in Lake Mead National Recreation Area, USA: Occurrence and biological uptake

PLOS | May 4th, 2020

Microplastics are an environmental contaminant of growing concern, but there is a lack of information about microplastic distribution, persistence, availability, and bio

Microplastics are an environmental contaminant of growing concern, but there is a lack of information about microplastic distribution, persistence, availability, and biological uptake in freshwater systems. This is especially true for large river systems like the Colorado River that spans multiple states through mostly rural and agricultural land use. This study characterized the quantity and morphology of microplastics in different environmental compartments in two large reservoirs along the Colorado River: Lakes Mead and Mohave, within Lake Mead National Recreation Area. To assess microplastic occurrence, surface water and surficial sediment were sampled at a total of nine locations. Sampling locations targeted different sub-basins with varying levels of anthropogenic impact. Las Vegas Wash, a tributary which delivers treated wastewater to Lake Mead, was also sampled. A sediment core (33 cm long, representing approximately 19 years) was extracted from Las Vegas Bay to assess changes in microplastic deposition over time. Striped bass (Morone saxatilis), common carp (Cyprinus carpio), quagga mussels (Dreissena bugensis), and Asian clams (Corbicula fluminea) were sampled at a subset of locations to assess biological uptake of microplastics. Microplastic concentrations were 0.44–9.7 particles/cubic meter at the water surface and 87.5–1,010 particles/kilogram dry weight (kg dw) at the sediment surface. Sediment core concentrations were 220–2,040 particles/kg dw, with no clear increasing or decreasing trend over time. Shellfish microplastic concentrations ranged from 2.7–105 particles/organism, and fish concentrations ranged from 0–19 particles/organism. Fibers were the most abundant particle type found in all sample types. Although sample numbers are small, microplastic concentrations appear to be higher in areas of greater anthropogenic impact. Results from this study improve our understanding of the occurrence and biological uptake of microplastics in Lake Mead National Recreation Area, and help fill existing knowledge gaps on microplastics in freshwater environments in the southwestern U.S.

Mid-Kaweah Groundwater Sustainability Agency Groundwater Sustainability Plan

Mid-Kaweah Groundwater Sustainability Agency (MKGSA) | December 18th, 2019

Middle Santa Ana River Watershed TMDL Task Force

Santa Ana Watershed Project Authority (SAWPA) | July 5th, 2018

The Task Force is an 18-agency collaborative effort organized by the Santa Ana Watershed Project Authority. It was formed in January 2006 to coordinate water quality impr

The Task Force is an 18-agency collaborative effort organized by the Santa Ana Watershed Project Authority. It was formed in January 2006 to coordinate water quality improvement activities related to bacteria in the Middle Santa Ana River Watershed. The activities were designed to manage or eliminate sources of bacterial indicators in local waterbodies. The Task Force supports on-going source investigation efforts to identify major sources of bacterial indicators and to understand how to best address them. Task Force resources are allocated on a risk-reduction priority basis in order to achieve compliance where it will provide the greatest improvement in public health.

Minerals of California Bulletin No. 113

State of California | February 15th, 1938

Minimizing the Impact of Cannabis Cultivation on California Lands and Waterways

California State Water Resources Control Board (SWRCB) | February 17th, 2017

Following recent changes in state law and voter-approved initiatives, California’s commercial cultivation of cannabis for recreational and medical use is expected to gr

Following recent changes in state law and voter-approved initiatives, California’s commercial cultivation of cannabis for recreational and medical use is expected to grow significantly. The State Water Resources Control Board has adopted a state cannabis policy to set up strict environmental standards, and a permitting system to protect local surface water from dewatering, protect water habitat and prevent pollution in the state’s rivers and streams. Left unregulated, cannabis cultivation can pose serious threats to water quality and the environment. Cannabis cultivation impacts include the release of fertilizers, pesticides and other supplements that degrade water quality and threaten wildlife. Excessive water diversions can injure fish or even dewater smaller streams. The physical alteration of the land can harm stream habitat and wildlife by the sediment and debris that is deposited in waterways by unregulated cultivation. Overview: The State Water Board’s “Cannabis Cultivation Policy, Principles and Guidelines for Cannabis Cultivation” (Policy) will be implemented through a water quality permit and a water right. The water quality permit is referred to as a Statewide General Order for Cannabis Cultivation Activities (Cannabis General Order). The water right is referred to as a Cannabis Small Irrigation Use Registration. Tiered Approach: The Cannabis General Order consists of a tiered permit structure based on threat to water quality. Tier 1 Cannabis Cultivators have a disturbed area greater than 2,000 square feet and less than 1 acre (43,560 square feet). Tier 2 Cannabis Cultivators have a disturbed area equal to or greater than 1 acre.

Modeling Barriers and Levee-Break Effects on Delta-Wide Salinity

Delta Stewardship Council (Delta Council) | February 18th, 2016

Modeling Cost, Energy, and Total Organic Carbon Trade-Offs for Stormwater Spreading Basin Systems Receiving Recycled Water Produced Using Membrane-Based, Ozone-Based, and Hybrid Advanced Treatment Trains

American Chemical Society (ACS) | January 31st, 2019

To address water scarcity, cities are pursuing options for augmenting groundwater recharge with recycled water. Ozone-based treatment trains comprising ozone and biologic

To address water scarcity, cities are pursuing options for augmenting groundwater recharge with recycled water. Ozone-based treatment trains comprising ozone and biologically activated carbon potentially offer cost-effective alternatives to membrane-based treatment, the standard process for potable reuse in numerous countries. However, regulations in multiple states effectively limit the extent to which ozone-based treatment alone can produce recycled water for groundwater recharge. To investigate the trade-offs between treatment costs and regulatory constraints, this study presents methods for modeling and optimizing designs for (1) producing recycled water using membrane-based treatment, ozone-based treatment, and hybrid treatment trains comprising ozone-based treatment with a membrane sidestream, and (2) delivering that water to stormwater spreading basins. We present a case study of Los Angeles, CA, to demonstrate the model’s application under realistic conditions, including regulations that limit spreading recycled water based on its concentration of total organic carbon and the extent of dilution. While the membrane-based treatment train exhibits economies of scale, we demonstrate how regulatory constraints create a diseconomies of scale effect for hybrid treatment systems because larger scales necessitate a higher proportion of recycled water undergo membrane treatment. Nevertheless, relative to membrane-based treatment, we identify opportunities for ozone-based or hybrid treatment trains to reduce treatment costs and energy use by up to 62% and 59%, respectively, for systems with up to 1 m3/s (23 million gallons per day) mean water recycling rate, potentially lowering the barrier for decentralized water recycling systems. This modeling approach could inform planning and policy regarding recycled water projects for groundwater recharge through spreading basins and, with additional modification, other potable reuse applications.

Modeling Land Subsidence Using InSAR and Airborne Electromagnetic Data

American Geophysical Union (AGU) | March 13th, 2019

Land subsidence as a result of groundwater overpumping in the San Joaquin Valley, California, is associated with the loss of groundwater storage and aquifer contaminatio

Land subsidence as a result of groundwater overpumping in the San Joaquin Valley, California, is associated with the loss of groundwater storage and aquifer contamination. Although the physical processes governing land subsidence are well understood, building predictive models of subsidence is challenging because so much subsurface information is required to do so accurately. For the first time, we integrate airborne electromagnetic data, representing the subsurface, with subsidence data, mapped by interferometric synthetic aperture radar (InSAR), to model deformation. By combining both data sets, we are able to solve for hydrologic and geophysical properties of the subsurface to effectively model the complex spatiotemporal process of deformation. The resulting model reveals that roughly 3 m of subsidence has occurred at one location of our study area from 1990 to 2018. This model also allows us to predict subsidence more accurately under future hydrologic scenarios, which is needed to develop plans for sustainable groundwater use.

Modern groundwater reaches deeper depths in heavily pumped aquifer systems

Nature Portfolio (Springer Nature) | September 7th, 2022

Deep groundwater is an important source of drinking water, and can be preferable to shallower groundwaters where they are polluted by surface-borne contaminants. Surface-

Deep groundwater is an important source of drinking water, and can be preferable to shallower groundwaters where they are polluted by surface-borne contaminants. Surface-borne contaminants are disproportionately common in ‘modern’ groundwaters that are made up of precipitation that fell since the ~1950s. Some local-scale studies have suggested that groundwater pumping can draw modern groundwater downward and potentially pollute deep aquifers, but the prevalence of such pumping-induced downwelling at continental scale is not known. Here we analyse thousands of US groundwater tritium measurements to show that modern groundwater tends to reach deeper depths in heavily pumped aquifer systems. These findings imply that groundwater pumping can draw mobile surface-borne pollutants to deeper depths than they would reach in the absence of pumping. We conclude that intensive groundwater pumping can draw recently recharged groundwater deeper into aquifer systems, potentially endangering deep groundwater quality.

Mojave Region Functionally Equivalent Storm Water Resources Plan

Mojave Water Agency (MWA) | October 4th, 2017

The State of California now recognizes the importance of incorporating storm water as a potential resource in a region’s water portfolio. Historically, storm water was

The State of California now recognizes the importance of incorporating storm water as a potential resource in a region’s water portfolio. Historically, storm water was thought of as a public risk (e.g., flooding) and a source of water quality impairment. Traditional approaches for storm water focused on diverting storm water into the storm drain system which ultimately and efficiently moved said water away from populated areas; the State is now supporting watershed-based approaches where storm water and dry weather runoff can yield benefits beyond flood control, such as water supply, water quality improvement, and habitat enhancement. To incentivize use of storm water, the State of California has linked storm water resources planning to state funding. Storm water and dry weather runoff capture projects seeking funding from any California bond act approved by voters after January 1, 2014 must be included in a Storm Water Resources Plan, which meets California Water Code. Regional water planning has a long history in the Mojave region. In 2005, agencies in the Mojave service area, that share a common concern for the area’s water resources, met and agreed to develop an Integrated Regional Water Management Plan (IRWMP). The Region’s first IRWMP identified, defined, and established strategies to capitalize on all water management opportunities that were present at that time or would become possible in the Mojave Region in the future. Since that time the IRWMP has acted as a forum for regular collaboration. The IRWMP is a living document and the regional objectives as well as strategies to improvement water management are regularly updated. The IRWMP was last updated in 2014. This Mojave Region Storm Water Resource Plan (SWRP) is an extension of the IRWMP process and is meant to bring an integrated and watershed-based approach to managing and creating benefits from storm water. This SWRP is regional and multi-agency. This SWRP includes all components required by the Water Code and will be submitted to the IRWM group. This SWRP will help entities in the Mojave Region identify, prioritize, and implement storm water projects.