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Filters: First Letter Of Title is D and Author is Phillip Trowbridge  [Clear All Filters]
2018
Jabusch, T.; Trowbridge, P.; Heberger, M.; Orlando, J.; De Parsia, M.; Stillway, M. 2018. Delta Regional Monitoring Program Annual Monitoring Report for Fiscal Year 2015–16: Pesticides and Toxicity. SFEI Contribution No. 864. Aquatic Science Center: Richmond, CA.

The primary purpose of this report is to document the first year (FY15/16) of pesticide monitoring by the Delta Regional Monitoring Program (Delta RMP). This document reports the results from samples collected monthly from July 2015 through June 2016. The data described in this report are available for download via the California Environmental Data Exchange Network (CEDEN) website.

Pesticide monitoring of the Delta RMP includes chemical analysis and toxicity testing of surface water samples. The parameters analyzed include 154 current use pesticides, dissolved copper, field parameters, and “conventional” parameters (ancillary parameters measured in the laboratory, such as dissolved/particulate organic carbon and hardness). Toxicity tests included an algal species (Selenastrum capricornutum, also known as Raphidocelis subcapitata), an invertebrate (Ceriodaphnia dubia, a daphnid or water flea), and a fish species (Pimephales promelas, fathead minnow). Toxicity testing included the evaluation of acute (survival) and chronic (growth, reproduction, biomass) toxicity endpoints. The surface water samples were collected from 5 fixed sites representing key inflows to the Delta that were visited monthly: Mokelumne River at New Hope Road, Sacramento River at Hood, San Joaquin River at Buckley Cove, San Joaquin River at Vernalis, and Ulatis Creek at Brown Road.

A total of 52 pesticides were detected above method detection limits (MDLs) in water samples (19 fungicides, 17 herbicides, 9 insecticides, 6 degradates, and 1 synergist). A total of 9 pesticides (5 herbicides, 3 insecticides, and 1 degradate) were detected in suspended sediments in 10 of a total of 60 samples collected during the study period. All collected samples contained mixtures of pesticides ranging from 2 to 26 pesticides per sample. From a total of 154 target parameters, 100 compounds were never detected in any of the samples.

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Jabusch, T.; Trowbridge, P.; Heberger, M.; Guerin, M. 2018. Delta Regional Monitoring Program Nutrients Synthesis: Modeling to Assist Identification of Temporal and Spatial Data Gaps for Nutrient Monitoring. SFEI Contribution No. 866. Aquatic Science Center: Richmond, CA.

Nutrient loads are an important water quality management issue in the Sacramento-San Joaquin Delta (Delta) and there is consensus that the current monitoring activities do not collect all the information needed to answer important management questions. The purpose of this report is to use hydrodynamic model outputs to refine recommendations for monitoring nutrients and related conditions in the Delta. Two types of modeling approaches were applied: 1) volumetric water source analysis to evaluate the mix of source waters within each subregion; and 2) particle tracking simulations.The analysis revealed that each Delta subregion has a unique “fingerprint” in terms of how much of its water comes from different sources. Three major recommendations for a future monitoring design were derived from this analysis:

Recommendation #1: The subregions proposed for status and trends monitoring in a previous report should be redrawn to better reflect the mixtures of source waters.

Recommendation #2: Long-term water quality stations are needed in the North Delta, Eastside, and South Delta subregions.

Recommendation #3: Areas with a long-residence time and where mixing of different water sources occurs are potential for nutrient transformation hotspots. High-frequency water quality mapping of these areas has the

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