Certified irrigation contractors install, maintain and repair irrigation systems.
https://www.irrigation.org/IA/Certification/Landscape-Certifications/CIC/IA/Certification/CIC.aspx
Certified irrigation designers establish specifications and design drawings for irrigation projects.
https://www.irrigation.org/IA/Certification/Landscape-Certifications/CID/IA/Certification/CID.aspx
Certified landscape irrigation auditors are involved in the quantification of landscape irrigation water use.
https://www.irrigation.org/IA/Certification/Landscape-Certifications/CLIA/IA/Certification/CLIA.aspx
Certified landscape water managers evaluate, operate,manage and improve landscape irrigation systems to achieve the highest level of water conservation possible.
https://www.irrigation.org/IA/Certification/Landscape-Certifications/CLWM/IA/Certification/CLWM.aspx
To become a certified as an Irrigation Landscape Contractor, an applicant must have a minimum of three (3) years experience working with the construction, repair, maintenance, improvement, and alteration of a landscaping irrigation system and/or educational experience. Field experience must be acquired after January 1, 1997 while employed under a certified contractor. New legislation taking effect approximately July 15, 2010 will change the experience requirements to: a minimum of 3 year’s experience within the past 15 years in the field of landscape irrigation. Field experience acquired after January 1, 1997 must comply with the requirements of P.L. 1991, c. 27 (C.45:5AA et seq.)(cf:P.L.1991, c. 27, s.4).
https://www.state.nj.us/dca/divisions/codes/advisory/Landscp_Irr_Cont.html
You must be certified to test a backflow prevention device assembly in all states.
https://newwa.org/BackflowCC/ProgramInformationCourseDescriptions.aspx
ASSE professional qualifications standards established minimum industry requirements for backflow prevention assembly testers, backflow prevention assembly repairers, and cross-connection control surveyors.
https://www.asse-plumbing.org/personnel-certification/certifications/backflow-prevention/
https://www.state.nj.us/dca/divisions/codes/advisory/Landscp_Irr_Cont.html