ABSTRACT. Illicit psychostimulant use is increasing across the United States leading to significant morbidity and mortality. A 2019 cross sectional study found that individuals with self reported methamphetamine use disorder in the US has tripled since 2015. The downstream comorbidities associated with methamphetamine and other psychostimulants like cocaine, ketamine and phencyclidine result in increased healthcare utilization, medication nonadherence, infectious complications of drug use, and worsening mental health and trauma. Despite its importance, surveillance of psychostimulant use remains suboptimal; most existing surveillance strategies utilize large national self-report sampling or data from emergency department and substance use disorder clinic urine drug screens resulting in significant bias. This surveillance data is utilized to inform national public health priorities and on a community scale, allocation of resources to address substance use disorders. Wastewater-based epidemiology is a potential option to conduct population level drug surveillance. By measuring key parent compound and metabolites in wastewater networks, a prevalence estimate of drug use and trends of use over time can be visualized. By varying the location of sample collection in the wastewater network, substance use data can be described at a large wastewater treatment plant catchment area or at the community level by measuring substances at individual street level manholes. Our ongoing fast track SBIR leverages wastewater networks to develop and commercialize an opioid assay that measures both parent opioids as well as key metabolites that indicate consumption. This administrative supplement iterates on our successful parent grant by selecting four psychostimulants of

PROJECT NARRATIVE. Illicit psychostimulant use disorder results in significant morbidity and mortality, but unlike opioid use disorder, lacks effective treatment pharmacotherapy options. Behavioral therapy and outreach to vulnerable populations is therefore a critical component of addressing increasing psychostimulant use disorder in the United States. This administrative supplement develops a wastewater-based psychostimulant assay panel to understand population level trends in illicit psychostimulant use across wastewater catchment areas.