Changing patterns in water toxicity associated with current use pesticides in three California agriculture regions

Abstract

Regulation of agriculture irrigation water discharges in California, USA, is assessed and controlled by its 9 Regional Water Quality Control Boards under the jurisdiction of the California State Water Resources Control Board. Each Regional Water Board has developed programs to control pesticides in runoff as part of the waste discharge requirements implemented through each region's Irrigated Lands Regulatory Program. The present study assessed how pesticide use patterns differ in the Imperial (Imperial County) and the Salinas and Santa Maria (Monterey County) valleys, which host 3 of California's prime agriculture areas. Surface-water toxicity associated with current use pesticides was monitored at several sites in these areas in 2014 and 2015, and results were linked to changes in pesticide use patterns in these areas. Pesticide use patterns appeared to coincide with differences in the way agriculture programs were implemented by the 2 respective Regional Water Quality Control Boards, and these programs differed in the 2 Water Board Regions. Different pesticide use patterns affected the occurrence of pesticides in agriculture runoff, and this influenced toxicity test results. Greater detection frequency and higher concentrations of the organophosphate pesticide chlorpyrifos were detected in agriculture runoff in Imperial County compared to Monterey County, likely due to more rigorous monitoring requirements for growers using this pesticide in Monterey County. Monterey County agriculture runoff contained toxic concentrations of pyrethroid and neonicotinoid pesticides, which impacted amphipods (Hyalella azteca) and midge larvae (Chironomus dilutus) in toxicity tests. Study results illustrate how monitoring strategies need to evolve as regulatory actions affect change in pesticide use and demonstrate the importance of using toxicity test indicator species appropriate for the suite of contaminants in runoff in order to accurately assess environmental risk. Integr Environ Assess Manag 2018;14:270-281. © 2017 SETAC.

Extracts from benthic anatoxin‐producing Phormidium are toxic to 3 macroinvertebrate taxa at environmentally relevant concentrations

“…Initial concerns related to toxic benthic cyanobacteria have focused on human health risks (Wood et al ), the risk to terrestrial animals (in particular stock and dogs; Mez et al ; Gugger et al ), and impacts on higher trophic level species (Wood et al ); however, these toxins can also affect macroinvertebrates (DeMott et al ; Toproska et al ). The potential for toxicity to arthropod macroinvertebrates is of particular concern because some of the neurotoxic cyanotoxins bind to neuroreceptors targeted by currently used pesticides (Aboal et al ; Da S. Ferrão‐Filho and Kozlowsky‐Suzuki 2011) that are known to impact aquatic ecosystems (Dirzo et al ; Morrissey et al ; Anderson et al ). The potential for cyanontoxins and current‐use pesticides to have similar effects on standard test species could confuse our determination of the causes of aquatic ecosystem toxicity.…”

Fate of Pyrethroids in Freshwater and Marine Environments

“…Generally, the past and on-going water survey programs setup in California have yielded an important and valuable amount of data on the occurrence of pyrethroids. These studies demonstrated that one or two pyrethroids were frequently present in whole water samples, and that the dominant active compound differed in space and time (both years and seasons), reflecting the distinct agricultural targets, shifts in usages, and emissions from urban pest control [11,19]. A metadata analysis gave the integrated view that cyhalothrin and bifenthrin were the compounds most frequently exceeding Regulatory Threshold Levels in surface freshwater of the USA and reached higher maxima in concentration [2].…”

“…The occurrence of individual pyrethroids varies geographically and seasonally as a response to agricultural use [19], and the consequent emission to the water, but probably also to different seasonal and site degradation potential. In Hospital Creek, a tributary of the San Joaquin River (Central California), bifenthrin was responsible for the greatest part of the toxicity of particles, whereas cyhalothrin was the prominent toxicant of particles in Ingram Creek, another tributary located less than 50 km away from the former [14].…”

“…In the case where the rate of inputs of pyrethroids would compensate for their degradation, pyrethroid occurrence may become more continuous and their behavior may then be assimilated to that of "quasi persistent organic pollutants", with secondary transport evading them away from their application area. In California, past and current monitorings have demonstrated that there is a persistent threat to aquatic ecosystems because of current-use pesticides, with an increasing share by pyrethroids [19].…”

Monitoring fish, benthic invertebrates, and physicochemical properties of surface water for evaluating nonpoint source pollution control in coastal agricultural watersheds

“…Similarly, agricultural watersheds can manifest spatial variation in water quality impairment due to differences in land use types, soils, nutrient inputs, and agricultural activities across the landscape (Demcheck et al 2004;Mueller-Warrant et al 2012;Poudel et al 2013). The impairment of physical and chemical properties of surface waters can negatively impact biological communities due to, for example, hypoxia and harmful algal blooms (Zhou et al 2008;Broussard and Turner 2009;Riseng et al 2011;Budria 2017;Breitburg et al 2018), increased levels of fecal bacteria (Brendel and Soupir 2017), elevated levels of suspended sediment (Basnyat et al 1999;Riseng et al 2011), or the presence of pesticides (Echeverría-Sáenz et al 2012;Anderson et al 2014Anderson et al , 2018.…”