Sacramento County Amphibian Pesticide Risk And IPM Outreach Mapping

Author Information

Lauren Ledesma, American River College, Data Acquisition: GEOG 350, Fall 2020

Abstract

Previous studies of animal and environmental samples have shown that endosulfan, chlorpyrifos, and trifluralin pesticide applications have detrimental effects on amphibian populations. Introduction and transport of these pesticides is attributed to application near river systems. Comparing California Pesticide Use Reporting data and spatial data from the National Hydrography Dataset identify which applications are most likely to negatively affect local amphibious populations. This can be used to target Integrated Pest Management resources and training for the best benefit to local amphibious species. Sacramento County applicators reduced their use chlorpyrifos, and trifluralin from 2015 to 2017 and avoided applying endosulfan for those three years. Future studies should review application in other counties in the Sacramento and an Joaquin River watersheds to protect local amphibian populations.

Introduction

Studies have shown that pesticides are easily absorbed or ingested by amphibian species due to their morphological traits (wet, sensitive skin) and diet (insects targeted by pesticides). Pesticides applied locally and upstream can be found later in water, sediment, and amphibian tissue samples study areas. Pesticides are also most highly concentrated along river streams (Luo & Zang, 2010). Three years of reported endosulfans, chlorpyrifos, and trifluralin pesticide applications in Sacramento County were examined for their proximity to local waterways. It can be inferred that the higher instance of these pesticides poses a greater risk to local amphibian populations. Integrated Pest Management program resources can be directed to the landowners who are using the most pesticide near stream and river systems.

Background

Multiple studies have been done to identify the groups of pesticides most likely to be negatively effecting amphibian populations. Endosulfans, chlorpyrifos, and trifluralin pesticides have been observed to be present in amphibian tissue samples and in environmental sample near declining populations (Fellers, et al., 2013) (Smalling, et al., 2015) (Sparling, Fellers, and McConnell, 2001). Larger scale spatial monitoring and modeling has also been trialed to better predict and understand pesticide transport and impacts throughout river systems (Luo & Zang, 2010) (Meyer & DeMars, 2018), though this approach to understanding pesticide impact appears to be a newer and less used method. Meyer and DeMars said the California Pesticide Use Reporting spatial database was “largely untapped for sampling and research” purposes. Decreased pesticide application can be achieved through education and training in Integrated Pest Management (IPM) (Maupin & Norton, 2010). After identifying areas with large amounts of targeted pesticide, IPM program resources can be directed to the land owners.

Methods

The largest amount of project time and resources were spent working with the California Pesticide Use Reporting data (https://www.cdpr.ca.gov/docs/pur/purmain.htm). Data was available as delimited text files holding relational database tables (Graphic 1)and as section and township layers. Data was organized by year (2017 mot recent data) and by county. Sacramento County code was 34 and I focused on three years of data (2105, 2016, 2017). I parred down the data to endosulfans, chlorpyrifos, and trifluralin chemical codes (Table 1). For all three years in Sacramento County there were no endosulfans pesticide uses reported. I then used Pivotable to group data by the other two group of pesticides and by township-range-section unit used in the “Section” layer supplied by the state website. I used the “join” tool to create two new layers with attributes of pesticide use in pounds applied and acres treated.

Graphic 1: Database Tables Table 1: Chemical Codes Used

I used river system data from the National Hydrography dataset. I specifically used the “Flowline” layer for California and used “Select by Location” to create a subset of water within 1 mile of Sacramento County. I also subset that data to only include “Ftype” = ‘StreamRiver’ and ‘Artificial Path’ to exclude many of the man-made stormwater canals. This final set of river system line data was buffered by one quarter mile. Finally, I looked at the higher pesticide applications intersecting the buffer layer I created. These are the sections with landowners to target for increased IPM resources.

Results

When reviewing the yearly use of pesticides, it was noted that pesticide use for the targeted pollutant is already decreasing over the last three years (Graphs 2 & 3).

Graph 2: Chlorpyrifos Use 2015-2017 Graph 3: Trifularlin Use 2015 – 2017

Above are the maps showing the total pounds of pesticide from 2015, 2016, and 2017 applied by township section across Sacramanto County. There were no data points for endosulfan pesticide application for the study years or study area.

Analysis

After applying a quarter mile buffer to the hydrology line dataset, 47 sections with trifluralin applications, and 10 sections with chlorpyrifos intersected the buffer. No endosulfan was reported for the study area in the study timeframe. Also, it appears that before this study, pesticide application use was already declining.

Conclusion

It appears as though Sacramento County pesticide applicator are already avoiding one of the main pollutants that negatively affect amphibian populations and have been decreasing pesticide use over the last three years. This study did identify multiple areas where IPM outreach could potentially protect amphibian population by reducing pesticides applied near river and stream systems. Using CA PUR data or county assessor data could provide contact information for those applicators.

Future research could lengthen the time studied to see if decreased use is observed beyond years 2015-2017. Also, other counties should be studied, especially those within the Sacramento and San Joaquin River watershed, as they could be contributing pesticides that get transported downstream..

References

Fellers, Gary M., Donald W. Sparling, Laura L. McConnell, Patrick M. Kleeman, and Leticia Drakeford. "Pesticides in amphibian habitats of Central and Northern California, USA." In Occurrence, Fate and Impact of Atmospheric Pollutants on Environmental and Human Health, pp. 123-150. American Chemical Society, 2013.

Luo, Yuzhou, and Minghua Zhang. "Spatially distributed pesticide exposure assessment in the Central Valley, California, USA." Environmental Pollution 158, no. 5 (2010): 1629-1637.

Maupin, Jason, and George W. Norton. Pesticide Use and IPM Adoption: Does IPM Reduce Pesticide Use in the United States?. No. 320-2016-10486. 2010.

Meyer, Erik W., and Christopher DeMars. "A Simplified Approach to Using Pesticide Use Reporting To Prioritize Pesticide Risk in California’s National Parks." In Managing and Analyzing Pesticide Use Data for Pest Management, Environmental Monitoring, Public Health, and Public Policy, pp. 405-430. American Chemical Society, 2018.

Smalling, Kelly L., Rebecca Reeves, Erin Muths, Mark Vandever, William A. Battaglin, Michelle L. Hladik, and Clay L. Pierce. "Pesticide concentrations in frog tissue and wetland habitats in a landscape dominated by agriculture." Science of the Total Environment 502 (2015): 80-90.

Sparling, Donald W., Gary M. Fellers, and Laura L. McConnell. "Pesticides and amphibian population declines in California, USA." Environmental Toxicology and Chemistry: An International Journal 20, no. 7 (2001): 1591-1595.