A farm is placed in one of three tiers based on its risk to water quality: tier 1 being the lowest risk and tier 3 being the highest. Just as monitoring requirements vary, so too does the usefulness of the data collected. The variance in monitoring information value depends on four factors: where, when, and what parameters are collected, as well as what test organisms are used to assess water and sediment toxicity. There are also noteworthy differences in the usefulness of data depending on whether data is collected from surface water or groundwater. While this chapter largely focuses on surface water, the challenges of groundwater monitoring and assessment will also be addressed. The location of the monitoring station is an important element in identifying what farm is polluting and to what extent. For example, upstream edge-of-field monitoring on a tributary offers more precise and detailed data on the pollutants discharging from surrounding farm; whereas data from a monitoring station located downstream along the main stem of a river are a composite of all upstream sources, making the task of teasing out probable non-point sources of pollution near-impossible The timing of data collection is also important because water quality can change during and after storm or irrigation events, or during or after fertilizer or pesticide applications, increasing pollutant concentrations. If monitoring data were taken before applying a pesticide, for example,cut flower transport bucket that information might not accurately portray the pollutants present in the waterways for the next several months. The issue of timing is even more problematic when testing groundwater; research has shown that it can often take decades for leached pollutants, particularly, nitrates, to show up in groundwater .
Thirdly, the parameters limit the extent of knowledge about the health of a given waterway. For example, collecting basic parameters, such as dissolved oxygen, turbidity, temperature, nutrients, metals, and pH, provides a good baseline by which to assess water health, but other important parameters, such as the amount of a specific prevalent pesticide in the water column, might be overlooked, and could be the key to more accurate problem identification. Finally, certain test organisms are more appropriate for certain pollutants. For example, Ceriodaphnia dubiais an appropriate test organism for testing water toxicity, while Hyalella aztecais more suited for assessing sediment toxicity. These two are commonly used in regulatory monitoring programs, however, other new classes of pesticides in the offing will require new test organisms, ones that are not part of the current cadre of test organisms used for regulatory monitoring in the Central Coast region and California in general. For example, a more suitable test organism to use for burgeoning classes of pesticides, such as neonicotinoids, but one that was not incorporated into monitoring programs until 2015, is Chironomous dilutus. Tier 1 and 2 water quality monitoring is conducted in the main stem of a tributary and reported as an aggregate twice a year. The usefulness of these data pales in comparison with that of individual discharge data taken at the edge-of-field from tier 3 farms. One of the biggest concerns among growers during the drafting and implementation of the 2012 Ag Waiver was public disclosure. Farmers soon to be classified in tier 3 were concerned about reporting individual discharge water quality data due to matters of privacy and value of information, but also due to fear of being regulated as point source dischargers.
Three factors that weigh heavily on tier criteria are a farm’s size, risk to nitrate pollution, and risk to water column toxicity. Mounting scientific evidence of nitrate groundwater contamination as well as pressure from environmentalists and environmental justice groups elevated the nitrate issue to the top of the agenda during the 2012 Ag Waiver negotiation process. Additionally, a series of several scientific studies from the Granite Canyon Laboratory pointed to two particular types of organophosphate pesticides—diazinon and chlorpyrifos—as the culprits of water toxicity in the region. While pesticides did not receive specific attention in the first Agricultural Waiver, these two pesticides found their place at the top of the agenda during the 2012 regulatory process over a long list of other potentially harmful pesticides used in the region. Agricultural use of chlorpyrifos and diazinon has decreased dramatically in California’s Central Coast region over the past decade .However, while chlorpyrifos use in the region has plummeted, statewide use has stayed relatively consistent over the past decade, with minor fluctuations. What causal factors drove the regional chlorpyrifos and diazinon decline, and how much of the decrease can be attributed to the 2012 Agricultural Waiver? What conditions made the chlorpyrifos decline possible in the Central Coast region, but not in other regions or California as a whole? What societal, environmental and regulatory implications have resulted from farmers’ decisions to stop using both chemicals? The following section explores these questions by assessing data collected from interviews, survey responses, a thorough review of policy related documents, water quality information, organic production data and pesticide use records in three different California regions. Survey responses were collected from a subset of questions in a 2015 study on growers’ opinions of water quality management practices and policies in the Central Coast Region .
The set of survey questions relevant to this study asked growers if and how their use of chlorpyrifos and diazinon had changed since the Agricultural Waiver was implemented. Sixty-five growers responded to this optional part of the survey. Forty-seven of the 65 reported a change in chlorpyrifos and diazinon practices; their responses are reported below. Results from the survey and other data suggest that a grower’s decision to apply the two pesticides or not depends on several factors, including specific regulatory requirements embedded in the 2012 Ag Waiver as well as regulations generally, concerns over workers safety, harm to the environment, the cost of pesticides and their application, the availability of alternatives to manage pests, as well as the extent of pest damage and the value of the crop; each of these will be discussed in more detail. Another motivation for the decline in diazinon and/or chlorpyrifos use was that growers simply did not like using the two pesticides knowing they caused harm to their workers and the environment. It appears that growers were aware of the growing scientific evidence documenting the impacts of chlorpyrifos and diazinon on the environment, ranging from water and air quality to small invertebrates to human health. Of the survey responses, 5 stated they stopped using the pesticides because of worker safety, while 10 cited environmental factors as their motivation. Selected quotes from survey responses are reported below.Several pesticides are popping up as the next big threat to water quality . Malathion is the third most commonly used OP insectidide next to diazinon and chlorpyrifos with similar chemical characterists, yet interestingly,procona flower transport containers was not targeted in the 2012 Ag Waiver. Imidicaloprid is in the neonicatinoid class, and studies have linked the pesticide to bee colony collapse disorder . And third, pyrethroid chemicals, such as bifthenthin and lambda-cyhlalothrin, are being linked to sediment toxicity issues in the region. While less toxic than OP pesticides, neonicotinoids and pyrethroids have longer halflives. As chlorpyrifos and diazinon have steadily decreased, many of these new pesticides, which are differently or equally as harmful as OPs, have increased. To address if growers have switched to other chemicals to replace diazinon and chlorpyrifos in the Central Coast region, growers’ use of possible substitutes were assessed. Two datasets were reviewed: the University of California Integrated Pest Management reports, CDPR pesticide use data, as well as scientific literature. In Monterey County , chlorpyrifos use on broccoli declined by 86% from 2000 to 2013, yet the total pesticide use on broccoli only declined by 47% over those years. Were growers substituting chlorpyrifos for another pesticide to control cabbage maggots? UC IPM reports show that one of the only viable alternatives for use on a commonly targeted pest is diazinon.
From pesticide use records, it is apparent that broccoli growers are not readily switching to diazinon, since it comes with the same baggage of regulatory and environmental problems as its counterpart. In response to the growing demand for an alternative pest management strategy to control cabbage maggot, a new study by Joseph and Zarate in the Journal of Crop Protection explored at least eleven other insecticides with similar or superior efficacy to chlorpyrifos on cabbage maggots; of these five of these are pyrethrins plus pyrethroids, and one is a neonicotinoid. To identify if growers were switching over to any of these five promising, but potentially environmentally-harmful, new pesticides, CDPR use data on broccoli was assessed for each chemical. Results from this analysis showed that while these alternative pesticide numbers are still relatively small, growers might be increasingly turning to them in the future, especially if cabbage maggot pest problems escalate and the value of broccoli continues to rise. Diazinon’s demise has been even starker in lettuce than chlorpyrifos on broccoli in the Central Coast, as well as in the two other regions assessed in this study and the state as a whole. From 2000 to 2013, diazinon use on lettuce in Monterey County dropped by 99% compared to a 26% drop in the total pesticide use on lettuce, with diazinon removed. However, data from UC IPM reports and CDPR pesticide use data, as well as scientific literature do not suggest a widespread switch to other pesticides, rather organic practices might be the larger force. Diazinon use on lettuce crop pests is more diversified, making any switch from diazinon to another chemical more dispersed. With broccoli, because chlorpyrifos use is limited to controlling cabbage maggots, a switch to another chemical was more easily identifiable. Diazinon use on lettuce, on the other hand, has historically been used to control at least six different pests , each opening up a pandora’s box of alternative chemicals. CDPR pesticide data on diazinon’s use on Monterey County lettuce shows no dramatic chemical-for-chemical switch. For example, as diazinon dramatically falls, no single pesticide rises up to take its place. Because diazinon’s use on lettuce was so varied, it is logical that several different chemicals might be used in its stead to fit one or more specific needs pest needs.The lack of readily available pesticide alternatives for use on broccoli’s cabbage maggot, or the scarce use of them thus far, alludes to growers simply using fewer chemicals to grow broccoli, and perhaps switching to organic farming practices. The same appears to be true for lettuce growers, although the data are more limited. The option of switching to organic production with higher profit margins and the consumer demand for less chemical use offer appealing motives for many growers to curtail their diazinon and chlopryifos use, in addition to other pesticides. The number of farms, value and acreage of organic production has blossomed over the past decade in the Central Coast. The top three agricultural producing counties in the region have steadily increased the amount of land in organic production every year. In San Luis Obispo County, the conversion to organic was even more staggering: In 2005, 4,493 acres were dedicated to organic production and by 2014 50,636 acres were grown organically—an eleven-fold increase. In Santa Cruz County, 2,700 acres were under organically production in 2005, and by 2014 4,058 acres were grown organically. In Monterey County, the organic production nearly tripled, from 16,410 acres in 2005 to 46,570 acres in 2014. More specifically, in Monterey County organic production of broccoli doubled over the past decade and a half: 1,430 acres of broccoli were grown organically in 2000, increasing to 2,862 acres in 2015 . Organic’s proportion of the total broccoli grown in Monterey County also grew: in 2000, organic production accounted for 2.3 % , and by 2015, roughly 4.5% of all broccoli production was devoted to organic. Although organic still does not account for a significant portion of total Monterey County broccoli production and cannot explain the chlorpyrifos decline alone, corroborated with growers’ survey responses , it is safe to conclude that a transition to organic has played a role in the declining use of the two pesticides. While long-term longitudinal data was not available for organic head and leaf lettuce production in Monterey County to assess whether or not organic production played a role in diazinon’s decline, a related crop, spring mix, was available.