Alternatively, creating incentives for plastics to never be deposited in rivers to begin with...

"The results, published last November in Environmental Science & Technology, show that rivers collectively dump anywhere from 0.47 million to 2.75 million metric tons of plastic into the seas every year, depending on the data used in the models. The 10 rivers that carry 93 percent of that trash are the Yangtze, Yellow, Hai, Pearl, Amur, Mekong, Indus and Ganges Delta in Asia, and the Niger and Nile in Africa. The Yangtze alone dumps up to an estimated 1.5 million metric tons of plastic waste into the Yellow Sea."

https://www.scientificamerican.com/article/stemming-the-plas...

The "10 rivers carry 93%" figure quoted above is Schmidt et al. 2017 (Env. Sci. & Tech.). The field has revised it hard since: Meijer et al., Science Advances 2021 (open access, doi:10.1126/sciadv.aaz5803) finds 1,656 rivers account for 80% of global emissions (0.8-2.7 Mt/yr), not 10. Small rivers dominate: 830 rivers under 10 m3/s carry 30% of emissions, while the 33 largest rivers account for ~3%. Worth noting the lead author is at The Ocean Cleanup, so the revision came from inside the project itself.