Skip to Main Content

The microscale study consisted of 145 POCIS deployed at 66 independent sampling stations associated with 44 TCCCs between 05 November 2014 and 05 March 2020. Detailed information associated with each POCIS deployment is available in Supplementary Material, Appendix A. POCIS were deployed successively for at least two deployment windows at 48 of the 66 sampling stations, while the other 18 were sampled just once. Sampling stations were established downstream of all sampled TCCC and upstream of 24 TCCCs. Eradication dates (date each TCCC was last active when raided by law enforcement officers) were used as the best available estimate of the last pesticide application date. Timing for installing POCIS devices following the eradication date varied between 26 and 31,303 days (mean: 418; sd: 266). Approximately 29% of all POCIS (n = 42) were deployed during the first precipitation season (i.e., November − March) following eradication (Table 2), 49% during the second season, and 22% during the third or later precipitation season. POCIS membranes were deployed in the field for a mean window of 64 days (range: 17–252 days). Alvarez (2010) notes that POCIS may be deployed for any length of time, given that deployment time is known to account for variable sampling rates (volume of water sampled though POCIS per unit time). Thus, extended deployments are not a factor when determining chemical presence.

Table 2

Quantity of POCIS installed as part of the microscale study summarized by the in-stream deployment location in relation to each trespass cannabis cultivation complex and number of rain seasons following the eradication date

Rain seasons following eradication dateDeployed POCIS
DownstreamUpstream
36 
42 29 
3 + 23 
Rain seasons following eradication dateDeployed POCIS
DownstreamUpstream
36 
42 29 
3 + 23 

Close Modal

or Create an Account

Close Modal
Close Modal