Guest Blog: A River Keeper’s Year

Guest Blog: A River Keeper’s Year

Chalk

We are, I suppose, river keepers, of sorts; my wife April, my other best friend Kerry, and me. Volunteers, it goes without saying, and largely self-taught. I lean on the writings of Simon Cooper and the knowledge of a river keeper friend in Dorset. Simon’s book is an authoritative handbook of river management woven into a charming narrative.

People we meet think of us first as fishermen, however, as we are always happy to explain, the greater part of our time on the river is spent not fishing it, but, rather, caring for it. Put simply, there would be no viable river without volunteers within organisations like our own river syndicate, The Wild Trout Trust, The Brecks: Fen Edge & Rivers Landscape Partnership, and the Lark Valley Catchment Partnership, nor without the support of the Environment Agency and Anglian Water. Much funding comes, directly or otherwise, from the National Lottery Heritage Fund. We like to moan and criticise, but these are people trying their best with limited resources.

The river in question is one of the very few, perhaps only 220, chalk streams in the world, almost all of which are found in England. This one, the river Lark, has been first abused and then neglected; used as a navigation in the 19^th century, then dredged in an act of environmental vandalism in the 20^th in a completely unsuccessful attempt at flood mitigation. Dredging makes flooding worse. I’ll explain.

The most important consideration in a river discharging its water is the gradient of the river. Our part of the river Lark is 19m above sea level. From there to where the river enters the river Great Ouse is 28km, at which point it is at sea level. Therefore, the gradient on the river is such that it falls just 67cm for every km. This gradient is typical of a chalkstream. If I dredge my part of the river by, say, a metre, the gradient will be reversed, and flooding will result; I will have created a pond.

A chalk stream is defined by the source of its water, which it receives from springs throughout the course of its length. Here is a clear example. Although the river is flowing from left to right on the picture, there is a spring in the centre which appears as the bright patch, with a bulge of water over it. The white water-crowfoot and water milfoil is being spread away from the spring like the filaments of an iris.

As the water comes directly from the chalk bed below the river, the temperature of a chalk stream never varies far from 10^oc throughout the year. It never freezes. Here’s why that matters.

Chalk streams did not exist until the land was adapted by man from the 17^th century onwards for agriculture. The river valleys were then areas of swamp; a channel was dug, which became the river, and hatches were installed on the river to block the flow as required and parallel channels known as carriers, dug, with connecting ditches. The relatively warm water was used to irrigate otherwise frozen land. The grazing animals were moved off the land at nightfall and the hatches closed, flooding the pasture; the hatches were opened in the morning, the land drained, and the animals returned, to enrich the soil with their dung. The men who performed these arduous, and daily, duties were known as “Drowners” and their accommodation, in the form of huts adjacent to the river, can still be seen.

(A Drowner’s Hut on the river Frome. The life preserver is a late addition)  

There is a movie, which I thoroughly recommend for its explanation of chalk streams and their management. It is called, “Chalk.”

Autumn and winter

We’ll begin at the end; fishing on the river ceases on the last day of October. Rods are put away, lines cleaned and stored, and memories of the summer banked as an investment to sustain us through the winter that follows. We love our sport; but, with that satisfaction come responsibilities. Stewardship of our river means leaving it in a better state than we found it.

Trout spawn in winter and we want to provide optimal conditions for this to happen. Trout are notoriously resistant to being told what to do, so, all we can do is prepare the river bed and invite them there. Preparation means creating areas of clean, loose gravel, in areas of good flow; a garden fork does the job. Then, as winter approaches, we look for signs of trout spawning in the river. The hen trout digs a trench with her tail, deposits her eggs as her mate spills his milt over them, and then covers them over. This is called a redd and appears on the river bed as a patch of brilliantly clean gravel.

(A trout redd in the bed of the river)

(November: The first frost)

There is something called a brash bundle; this is the building block of bank repair. About 2m long and tied with twine, hazel branches are best, but willow, which we have in abundance, will do, although it needs to be dried for a year, or it will take root where you would prefer it did not. Willows are pollarded, and the branches, “whips”, tied into bundles. We aim to make at least 200 each autumn, at the rate of 6 an hour.

(April on top of manufactured brash bundles)

December through to February are dark months. If the river levels allow, this is a good time for bank repairs. A river, for its integrity, depends on marginal vegetation, the roots of which bind the bank together; then a cushion of silt, which provides a filter to absorb nutrients washed off the land, and a place for invertebrates; then the river, which we would like to consist of bubbling water flowing over polished gravel. American signal crayfish are our enemy, for where the bank has a vulnerability – loss of marginal vegetation, typically on the outside of a bend – these crayfish will exploit it and burrow as much as a yard into the bank, which then collapses under its weight and in the face of the current. This invasive non-native species was brought into the UK as a fashionable and fast-growing foodstuff but escaped to the wild and outcompeted our native crayfish for nutrients available to them; American signals also transmit a fungal disease called ‘crayfish plague’, which is harmful to our native species, and can be spread by wet footwear and equipment.

If crayfish are the enemy, alder trees are our ally. Their red coloured roots provide strength. An alder will not, unlike a willow, produce unwelcome suckers; unlike a willow, it will not allow branches to trail in the water and take root in the river bed. We love alders, both for the tree and for the timber we harvest from it, as a welcome characteristic of the alder is its resistance to decay when used for construction in water. We plant up to 100 trees every year and the majority of these will be alders, although in the words of Ronald Blyth, “Alas, I will have long been with God before its trees could cast their shade on me.”

Notes:

Simon Cooper: Life of a Chalkstream. HarperCollins, 2015. ISBN 978-0007547883.

Chalk: The Movie:  https://www.fishingtv.com/video/chalk-bedrock-of-fly-fishing/

This blog was written by BFER Blogging Volunteer, Dr John Urquhart, as part of a series of blog posts exploring the year’s activities of a river keeper. Stay tuned to brecks.org for the next article,  in which John will turn to spring, the insects that appear and the beginning of the fishing season.

If you would like to write a blog post for BFER, we would love to hear from you! Contact our Volunteer and Engagement Officer, Nicole, at: nicole.hudson@suffolk.gov.uk