The International Maritime Organization (IMO) Ballast Water Management (BWM) Convention will enter into force today, 8 September 2017. As agreed at the last Marine Environmental Protection Committee session in July, the implementation dates of the Convention were amended so that existing ships (i.e. ships constructed before 8 September) will not be required to install treatment systems until the date of their first International Oil Pollution Prevention (IOPP) renewal survey after 8 September 2019. In the absence os a treatment system, the ballast water must be exchanged in accordance with local regulations. Danish Shipping has prepared a guide – The Little Blue Book on Ballast Water – to assist in compliance with the rules of the convention. The guide is intended to be on board the ships, so the crew can seek information when needed.