I've been looking up a bit about the Somerset levels. It is reclaimed marshland. Over centuries it has been used as farmland after the land was drained; at some point Dutch engineers were used back in the 17th century.
So if you neglect the drainage system, you are going to have a problem - pretty obviously?
For the last 15 years no dredging has been done on some of the rivers running through the levels; one of the first acts of the Environment Agency was to scrap a large proportion of the dredging equipment they inherited.
It comes down to this; maintenance needs doing but it is expensive and unglamorous. There aren't many brownie points in it. It was the same in IT; support was thankless because everyone expects things to be working. People working in support only ever got abuse when things didn't work, never praise when they did. Development of new application was where the praise and the promotions were.
So the EA hasn't been doing the maintenance work that it should. Transport London (who run the Tube?) have lengthened the intervals between inspections of the railway track; I have heard that Netword Rail have done the same. Years ago an old lad was on the TV. He used to work on reservoirs, clearing the culverts that drain water from the moors into local reservoirs. He went to inspect one - totally overgrown. Essential maintenance is being neglected on our infrastructure.
On the BBC this morning it transpires that right this minute, the environment agency is planning to make more of it's workers redundant; not something that "Lord" Smith mentioned the other day.
eta - Just found this:-
Equivalent quangos in the rest of the world are much smaller, the Environment Agency for England alone has more staff than the Canadian, Danish, French, German, Swedish and Austrian equivalents, combined!
So maybe they do need to lose a few.