Comparing Groundwater Quality in Public-Supply and Shallow Aquifers in the Monterey Bay and Salinas Valley Basins, California

U.S. Geological Survey (USGS) | December 17th, 2018

Groundwater quality in the Monterey–Salinas Valley Public-Supply and Shallow Aquifer Systems was investigated by the GAMA-PBP. The Monterey–Salinas Valley Pub

Groundwater quality in the Monterey–Salinas Valley Public-Supply and Shallow Aquifer Systems was investigated by the GAMA-PBP. The Monterey–Salinas Valley Public-Supply Aquifer System study unit (MS-PA) initially was assessed in 2005 (Kulongoski and Belitz, 2011). The Mon-terey–Salinas Valley Shallow Aquifer System study unit (MS-SA) was sampled in 2012–13 (Burton and Wright, 2018). The MS-PA and the MS-SA largely coincide areally; however, they represent different parts of the aquifer system vertically. The MS-PA examined deeper groundwater primarily used for public supply, whereas the MS-SA examined relatively shallow groundwater primarily used for domestic supply. The MS-SA was divided into four study areas. Three of these study areas combined (MS-SA3) were equivalent to the MS-PA study unit excluding a small sliver along the Carmel River. The fourth MS-SA study area, Highlands, is composed of the hills and mountains bordering the Salinas Valley. The MS-PA and the MS-SA study units have warm, dry summers and cool, moist winters. The average annual rainfall is 331 millimeters (mm; 13 inches, in.) with average annual temperatures of14 degrees Celsius (57 degrees Fahrenheit) in Salinas. The study units are drained by three main rivers and their tributaries: the Salinas, Pajaro, and San Lorenzo Rivers. Groundwater quality status and understanding assessments of the study units were based on data collected by the U.S. Geological Survey (USGS). In the MS-PA, additional inorganic data was obtained from the California State Water Resources Control BoardDivision of Drinking Water Public- Supply Well Water-Quality Database (Kulongoski and Belitz, 2011). A grid-based method to select wells was applied in both study units, which allows for an estimation of the proportions of the aquifer system with constituents at low, moderate, or high concentrations relative to regulatory and non- regulatory benchmarks for drinking-water quality established by the U.S. Environmental Protection Agency (EPA) or California State Water Resources Control Board Division of Drinking Water. The grid-based method provides statistically unbiased results and permits comparison of those results to other GAMA Priority Basin Project study areas (Belitz and others, 2010).

Comparing imidacloprid, clothianidin, and azoxystrobin runoff from lettuce fields using a soil drench or treated seeds in the Salinas Valley, California

Environmental Pollution (Elsevier) | October 10th, 2022

Neonicotinoid insecticide use has increased over the last decade, including as agricultural seed treatments (application of chemical in a coating to the seed prior to pla

Neonicotinoid insecticide use has increased over the last decade, including as agricultural seed treatments (application of chemical in a coating to the seed prior to planting). In California, multiple crops, including lettuce, can be grown using neonicotinoid treated seeds or receive a direct neonicotinoid soil application (drenching) at planting. Using research plots, this study compared pesticide runoff in four treatments: (1) imidacloprid seed treatment; (2) clothianidin seed treatment; (3) imidacloprid drench and an azoxystrobin seed treatment; and (4) a control with no pesticidal treatment. Neonicotinoid and azoxystrobin concentrations were measured in surface water runoff during six irrigations events in the 2020 growing seasons. Results showed runoff concentrations up to 1308 (±1200) ng L−1 for imidacloprid drench treatment, 431 (±100) ng L−1 for clothianidin seed treatment, 135 (±60) ng L−1 for imidacloprid seed treatment, 13 (±10) ng L−1 for azoxystrobin seed treatment (treatments averaged). The percent of applied mass in runoff over the entire sampling period varied by compound; the imidacloprid seed treatment and drench were similar (0.015 and 0.019%, respectively) to the clothianidin seed treatment (0.036%) while the azoxystrobin seed treatment was much higher (15%). Although the proportion of imidacloprid in runoff was similar for imidacloprid treatments, the mass applied during soil drench was > 4x the amount applied from the imidacloprid seed treatment. Surface soils were collected before planting and at the end of the trial. The neonicotinoids were detected in soil throughout the study and average maximum concentrations were 9–13 ng g−1; azoxystrobin was detected in only two soils at concentrations up to 0.57 ng g−1. These results elucidate the comparative mass runoff resulting from planting treated seed and soil drench applications and highlight the value of additional work to characterize off-site transport from the many commodities that may be utilizing treated seeds.

Comparing Local Groundwater Withdrawal Permitting Laws in the Southwest and California

Stanford University | October 13th, 2016

 For the first time in California’s history, the Sustainable Groundwater Management Act of 2014 (SGMA) aims to empower local agencies to sustainably manage the pumping

 For the first time in California’s history, the Sustainable Groundwater Management Act of 2014 (SGMA) aims to empower local agencies to sustainably manage the pumping of groundwater. A notable, but often unremarked, aspect of SGMA is that it provides Groundwater Sustainability Agencies (GSAs) with the power to adopt rules and regulations to establish “groundwater extraction allocations” (i.e., a permitting regime). California is the last of the seven southwest states — Arizona, California, Colorado, Nevada, New Mexico, Texas, and Utah — to introduce a permitting power, suggesting that the other southwestern states can inform GSAs looking to promote sustainability through the use of their new power to establish extraction allocations. 

Comparison of potential drinking water source contamination across one hundred U.S. cities

Nature Portfolio (Springer Nature) | December 13th, 2021

Drinking water supplies of cities are exposed to potential contamination arising from land use and other anthropogenic activities in local and distal source watersheds. B

Drinking water supplies of cities are exposed to potential contamination arising from land use and other anthropogenic activities in local and distal source watersheds. Because water quality sampling surveys are often piecemeal, regionally inconsistent, and incomplete with respect to unregulated contaminants, the United States lacks a detailed comparison of potential source water contamination across all of its large cities. Here we combine national scale geospatial datasets with hydrologic simulations to compute two metrics representing potential contamination of water supplies from point and nonpoint sources for over a hundred U.S. cities. We reveal enormous diversity in anthropogenic activities across watersheds with corresponding disparities in the potential contamination of drinking water supplies to cities. Approximately 5% of large cities rely on water that is composed primarily of runoff from non-pristine lands (e.g., agriculture, residential, industrial), while four-fifths of all large cities that withdraw surface water are exposed to treated wastewater in their supplies.

Comparison of the Performance of Different Bioassessment Methods: Similar Evaluations of Biotic Integrity from Separate Programs and Procedures

Journal of the North American Benthological Society (University of Chicago Press) | January 16th, 2006

Regional bioassessment programs of states, various federal agencies, and other governmental and private groups often use different methods to collect and analyz

Regional bioassessment programs of states, various federal agencies, and other governmental and private groups often use different methods to collect and analyze stream invertebrate samples. This lack of uniformity has created concern and confusion over the comparability of disparate sources of data, but few studies have attempted to evaluate differences in performance between methods or to reconcile the results produced from different methods. We conducted concurrent sampling at 40 sites in the eastern Sierra Nevada of California using 3 bioassessment methods to obtain directly comparable data sets. The riffle-based methods (University of California Sierra Nevada Aquatic Research Laboratory [UC-SNARL, Lahontan Water Board], California Stream Bioassessment Protocol, and US Forest Service Region 5) differed at each stage from field sample collection to laboratory processing and data analysis. We used a performance-based methods system to compare precision, uniformity, discrimination, accuracy, and correlations among multimetric Index of Biotic Integrity (IBI) scores and multivariate River Invertebrate Prediction and Classification System (RIVPACS)-type observed/expected (O/E) ratios. Reference and test sites were identified using local and upstream-watershed disturbance criteria, and invertebrate community measures and models were then developed to discriminate between reference and test sites. The more- intensive UC-SNARL method showed slightly, but consistently, greater sensitivity for discriminating impairment than the other 2 methods. The UC-SNARL method produced greater differences between reference- and test-site means relative to lower reference-site standard deviations than the other 2 methods. However, assessment scores were highly correlated among methods and distinguished reference from test sites with similar accuracy among methods despite the slight differences in performance. Our results show that differing bioassessment methods can yield very similar, effective discrimination of impaired biological condition even though they have multiple differences in field and laboratory protocols (mesh size, replication, area sampled, taxonomic resolution, total counts). Moreover, this conclusion did not depend on the approach taken to data analysis because both multimetric IBIs and multivariate RIVPACS-type O/Es were in close agreement. Methodological uniformity is important when coordinating monitoring programs, but our results suggest that data from multiple sources could potentially be used interchangeably and for cross-validation of assessments of stream biological integrity.

Comparison of U.S. Geological Survey and Bureau of Reclamation Water-Use Reporting in the Colorado River Basin

U.S. Geological Survey (USGS) | September 2nd, 2019

The use of water in the United States is arguably one of the most important factors determining water availability at any specific place and time. Numerous local, State,

The use of water in the United States is arguably one of the most important factors determining water availability at any specific place and time. Numerous local, State, and Federal entities develop, compile, and report water-use data, which can lead to confusing or conflicting information. This report was authored jointly by the U.S. Geological Survey (USGS) and Bureau of Reclamation (Reclamation) to compare and contrast the two agencies’ water-use information programs in the Colorado River Basin. The report also describes the legal drivers for each program, clarifies confusing terminol- ogy, compares the methods used, and contrasts the information reported by each agency. This detailed comparison demon- strates that these two Federal agencies have different missions, different programmatic drivers, and different user communi- ties, all of which lead to different approaches to water-use data collection, analysis, and reporting. This report highlights those differences and explains why the USGS and Reclamation programs exist and how the data serve different user communities. Even though the two water-use programs are different by design and purpose, the program comparison presented in this report has identified opportunities for closer coordination and sharing of information between the USGS and Reclamation, as well as program components where agency collaboration can improve water-use estimate methodologies. This comparison effort emphasizes that it is incumbent upon each agency to clearly define the meaning of the terms used and the appropri- ate application of the reported information to avoid confusion or the accidental misuse of the information. An additional benefit of this comparison effort is the formation of a joint USGS/ Reclamation water-use team that will continue to investigate opportunities to expand and coordinate future water-use data compilation and reporting.

Comparisons of Targeted-riffle and Reach-wide Benthic Macroinvertebrate Samples: Implications for Data Sharing in Stream-condition Assessments

Journal of the North American Benthological Society (University of Chicago Press) | January 1st, 2007

Recent comparisons of benthic macroinvertebrate (BMI) sampling protocols have shown that samples collected from different habitat types generally produce consis

Recent comparisons of benthic macroinvertebrate (BMI) sampling protocols have shown that samples collected from different habitat types generally produce consistent stream classifications and assessments. However, these comparisons usually have not included biological endpoints used by monitoring agencies, such as multimetric indices (e.g., benthic index of biotic integrity [B-IBI]) or observed- to-expected (O/E) indices of taxonomic completeness, as target variables, and estimates of method precision are rarely provided. Targeted-riffle (TR) and reach-wide (RW) benthic samples have been collected at thousands of sites across the western USA, but little guidance is available for understanding 1) the extent to which raw data sets can be combined in regional or large-scale analyses, 2) the degree of precision afforded by each method, or 3) the efficacy of cross-application of biological indicators derived from one sample type to the other. To address these issues, we used data from 193 sites in California where the Environmental Monitoring and Assessment Program (EMAP) collected the 2 samples side by side. We also conducted a separate study wherein 3 replicates of each sample type were collected from 15 streams to estimate minimum detectable difference (MDD) as a measure of each method’s precision. Metrics calculated from TR and RW samples showed similar dose–response relationships to stressors gradients and similar raw scoring ranges. Biological indices (B-IBI, O/E0, and O/E50) derived from RW samples were more precise than those derived from TR samples, but precision differences were not substantial. On average, pairwise differences in any index between TR and RW sample types were much less than the MDD associated with either sampling method. We observed a weak but consistent bias toward higher O/E50 scores from TR samples than from RW samples at the highest elevations and in the largest watersheds. Broad-scale condition assessments were nearly identical when B-IBI and O/E0 were used as endpoints, and assessments based on O/E50 were only slightly less similar. Our analyses indicate that raw data sets and biological indicators derived from TR and RW samples may be generally interchangeable when used in ambient biomonitoring programs.

Competition for water induced by transnational land acquisitions for agriculture

Nature Portfolio (Springer Nature) | January 26th, 2022

The ongoing agrarian transition from smallholder farming to large-scale commercial agriculture promoted by transnational large-scale land acquisitions (LSLAs) often aims

The ongoing agrarian transition from smallholder farming to large-scale commercial agriculture promoted by transnational large-scale land acquisitions (LSLAs) often aims to increase crop yields through the expansion of irrigation. LSLAs are playing an increasingly prominent role in this transition. Yet it remains unknown whether foreign LSLAs by agribusinesses target areas based on specific hydrological conditions and whether these investments compete with the water needs of existing local users. Here we combine process-based crop and hydrological modelling, agricultural statistics, and georeferenced information on individual transnational LSLAs to evaluate emergence of water scarcity associated with LSLAs. While conditions of blue water scarcity already existed prior to land acquisitions, these deals substantially exacerbate blue water scarcity through both the adoption of water-intensive crops and the expansion of irrigated cultivation. These effects lead to new rival water uses in 105 of the 160 studied LSLAs (67% of the acquired land). Combined with our findings that investors target land with preferential access to surface and groundwater resources to support irrigation, this suggests that LSLAs often appropriate water resources to the detriment of local users.

Compilation of 2018 Delta Levee Five-Year Plan Data

California Department of Water Resources (DWR) | December 14th, 2024

Information provided in the Plans of the participating 74 Levee Maintaining Agencies (LMAs) include the level of protection of the LMAS' levee system at the time of the c

Information provided in the Plans of the participating 74 Levee Maintaining Agencies (LMAs) include the level of protection of the LMAS' levee system at the time of the creation of the Plans, the proposed work within the next five years to bring the LMAS' levee system to their desired level of protection, and a summary of the cost related to the proposed work. Proposed work includes multi-benefit projects, levee projects to meet a desired level of protection, studies, emergency planning, habitat enhancement projects, and additional protection. Also in this report is a summary of the LMAs’ 2009 five-Year plans, which were submitted to DWR in accordance with the Delta Levees Special Flood Control Projects Program 2009 Five-Year Plan Solicitation.

Complete Report on Construction of the Los Angeles Aqueduct

City of Los Angeles | January 15th, 1916