Is silt slowly choking the system in the Fens?

Did the shrimp boats sit this high and dry in the Fisher Fleet at low tide a few years back..? I'm not so sure they did.

The tidal river's silting up so badly in Lynn that the council is looking to buy an amphibious vehicle to replace the ferry that runs from King Street to West Lynn.

The report to councillors makes quite interesting reading when it comes to the state of the Ouse - scroll down to the first agenda item here.

What's all this got to do with pike fishing, you might ask. Well the tidal Ouse is the end of a system of rivers and drains that stretches far inland. In recent years, siltation has caused problems in the Delph, when water wasn't cleared off the Washes because of the shrinking window when it could be run off via Welmore Sluice.

Reading between the lines regarding the recent renovation of the Relief Channel tail sluice, the Channel's going to be increasingly relied upon to discharge water, as it by-passes the silted up stretch of the tidal between Denver and Eau Brink. This could prove a blow to hopes that fishing on the Channel might improve once the gates were de-silted which allow the Ely Ouse to flow into the tidal between tides.

Things are changing fast out there. Not even the rain we've had over the wettest summer for nearly a century has been enough to scour the tidal. The tide comes in with more force than it goes out, meaning the flood brings in mud faster than the ebb can clear it.

Disaster might not be looming toworrow. But the tidal river governs how the entire system operates. And sooner or later, there's going to be a tipping point when it comes to actually getting water away. Take the new pumping station at St Germans, which can now move water out of the Middle Level  at all states of the tide.

This relieves the immediate risk from the Middle Level, but where does the water go against a rising tide - back upstream, adding to the problems of siltation upstream in the tidal, between St Germans and Denver.

This might make the Welney and Ouse Washes more prone to flooding - what they were designed to do, some will doubtless argue. But what happens as the tidal Ouse between Denver and Welmore becomes more silted, reducing the scope for clearing water off the Washes.

Click here for schematics which show how that part of the system works. See what I mean..?

Tides govern drains and rivers in the Fens

I have a theory the tides are going to play more of a part in pike fishing than they have for a few seasons right from the word go this autumn. The simple reason for this is that water from brim-full main drains and rivers is currently being pumped off or discharged between low tides.

The impact that this has, even miles inland, is that it brings some flow to the water. A few days ago, the bottom end of the Middle Level Drain was covered with azolla. Seeing a picture of it on Twitter, I took a detour to get a picture of it yesterday only to find it had almost disappeared - pumped off via the new pumping station at St Germans into the tidal Ouse.

The pumping station's not the only change on the Middle Level system. The sluice under the aqueduct at Mullicourt has now been removed, meaning when the pumps are running, the whole system's going to flow as far inland as the Sixteen Foot, Forty Foot, Popham's Eau and the Old Nene.

Tides govern the pumping regime, because it's cheaper to pump water at low tide than against the tide. One of this season's projects is to make a note of what the tides are doing before I go, to see how they impact on flows.

I know there are people who swear by moon phases. One thing the moon phase determines is the size of the tides, as they cycle between springs and neaps.

All that water, from the Ouse and its feeder rivers, to the main drains and the man-made sprawl of waterways that feed them, is connected. Fascinating place the Fens.