Starting in July 2017, the California State Lands Commission (CSLC) began assessing vessel owners and managers with civil penalties for violations of the agency’s ballast water management requirements. Due to the CSLC’s enforcement efforts, both the agency and those who represent vessel interests who find themselves in violation of the requirements have learned several lessons. In May 2019, John Berge of the Pacific Merchant Shipping Association moderated two seminars at which Nicole Dobroski (Assistant Chief, Marine Environmental Protection Division, CSLC) and Peacock Piper Tong + Voss LLP partner David Tong shared their respective experiences enforcing the CSLC’s requirements and defending those against whom the requirements are enforced. The first seminar was held in Richmond, California and the second seminar took place in Long Beach, California. Both seminars were attended by a wide range of industry stakeholders including vessel owners, agents, surveyors, claims handlers, and government interests.