Earlier quoted context omitted.
I think currently one of the biggest risks for The Netherlands is salinization. If there is not enough river water and the groundwater level is too low, sea water will push upward, contaminating the river beds and increasingly much soil around it. This summer they had to close locks to block seawater and to increase the fresh water level. Of course, this has a considerable economic damage, since it blocks inland ship…
Netherlands is also in a much worse position due to being downstream of literally everyone. It's going to be a huge future fight in the EU because all countries upstream will want to retain 'all' the water and the remaining low flow will still have all those countries their industries dumping toxic waste, meaning the ratio of water-waste will get ridiculous.
There is still enough water, it is just unevenly distributed over the year. Previously winter snow was retained in the Alps and released as it melted during the summer, nowadays winter rain immediately comes downstream as giant floods.
If upstream countries were able to retain a significant portion of those floods and release it as a trickle during the summer, The Netherlands wouldn't have any problems. It is literally impossible for it to be worse than it currently is.
Besides, most of the water used in The Netherlands does not come from the large rivers, but from local rainfall. The drought is due to sticking to the historical policy of trying to immediately get rid of any excess water, rather than retaining it locally. No need to do anything EU-wide to solve that, just get the farmers to accept that the land will be a bit soggy in the winter.