NOTE: "Outflow"; in other words water flows out of the River Thames into St Patrick's Stream and then into the River Loddon, joining the Thames again below Shiplake Lock

Left bank a mile above Shiplake Lock. The flow is AWAY FROM the Thames DOWN into the River Loddon.
There may be a small (3") weir. Only suitable for canoes and punts. (Skiffs would find difficulty because of narrow channels and trees). Beware of swans and fisherpersons.
See River Loddon which has downstream end of St Patrick's Stream so that Shiplake Lock is by-passed by this strange stream. (It is probably an old mouth of the River Loddon, which when Shiplake Weir was built then reversed its flow).

St Patrick’s Stream entrance
Entrance into St Patrick’s Stream (No Launches) Canoes & punts only!

1794: Report of a survey of the river Thames between Reading and Isleworth ... John Rennie (the Elder)

There is a back stream which carries away a considerable quantity of water into the river Lodden, much to the injury of the navigation above Corterel's [Shiplake] Lock.
This stream should be shut up with a low wier ; the ground on the Oxford side of the river should be rounded off, sloped, and footed-up with chalk. The channel on the Berks side of the ayt should be contracted, and a part of the lower end ballasted away to ease the turn in the barge Channel.

ON PATRICK'S STREAM by Joseph Asby-Sterry -

( Upon the River, where sedges shiver,
And willows quiver, you take your ease :
Upon the River, where ripples shimmer
While sunshine's dimmer beneath the trees !
Where blue skies glimmer and leaves are singing
Sweet fancies bringing, in leafy lays
Devoid of hurry and care and flurry
And ceaseless worry - in Summer Days ! )

IN Summer Days that light canoe,
You soon will find can carry two !
As glimmered gleams around it play,
A lazy trip you would essay,
And take a laughing lass as crew !
Her voice is low, her eyes are blue,
She loves to navigate with you
Secluded leafy water-ways
In Summer Days.

The River broad you quite eschew,
But Patrick's Stream meander through :
How short appears the longest day !
Because you have so much to say,
Half whispered in sedge-shaded bays -
In Summer Days

In Summer Days ! Ah ! life is sweet !
For you have found a choice retreat,
Where you can calmly rusticate
By stream-lapped lawns, and meditate,
Leaf-shaded from the broiling heat.
The waters ripple cool and fleet,
Your situation's hard to beat
'Neath leaves as clear as chrysoprase,
In Summer Days.

Perchance it would be indiscreet
Your silly nothings to repeat,
When, quite regardless of your fate,
You revel in a tete-a-tete !
And laugh and chatter, love and laze -
In Summer Days !

1880: Isis and Thamesis by Alfred J Church -

About a mile below Sonning, on the right-hand bank of the river, the traveller will see what looks like a tributary of the Thames, spanned by a somewhat long bridge.
I remember making an expedition to this place from Henley under the impression that it was the Loddon.
When we reached it we found that, contrary to the usual habit of tributaries, the water was flowing out, not in; we pursued our exploration, and after navigating for two or three miles a somewhat difficult channel, found ourselves at last in the real Loddon, and then, by still descending, in the Thames again.
A frugally minded traveller may thus avoid the toll which is payable at Shiplake Lock; but I must warn him, that, unless he values his time over cheaply, the diversion will cost him more than the threepence to which the Thames Conservators have reduced their charge.

1881: George Leslie, "Our River" -

the place [the entrance into St Patrick's Stream] is so concealed with rushes, that in coming down, if you do not look well out for the little foot-bridge, it is most likely you will miss it altogether.

[ No footbridge in 2004, nor tiny weir. ]

This backwater is called St. Patrick's Stream - why I do not know;  it is a very peculiar backwater, because it flows from the Thames itself into a tributary stream, and, united with the waters of the tributary, rejoins the main stream below the weir.  I know of no other backwater on the river by which you can avoid going through a lock;  the stream in St Patrick's Water is very strong, falling as it does all the way without arrest, whereas the main stream has a weir on it, with a fall of three feet six inches.

[ Shiplake Lock now has a drop of 5'1". In 2004 I commented:
The stream however is not strong (due to its weeds).  My maximum speed punting down it in 2004 was 4.50mph.  Weeds and trees were the problems.
In 2011 the stream was clearer and I probably reached 6 or 7mph. In two places I had to force through reeds.]

It is perhaps best to explore this stream on the down journey, as the labour of going up it is great.  The character of this little river is not very varied or interesting, but you meet no steam-launches, the water is clear, and there is an air of general wildness about it.  The only object of interest on it, is an old farmhouse about half-way up, with a little bridge over another small stream which flows also from the Thames, from above the weir;  you cannot pass, however, by this to the main river on account of a small weir across it.  Burrow Marsh, as this farm-house is called, has lately become the summer residence of my friend Mr. W. Field the artist, a younger son of the late Edwin Field;  he comes down here also in the winter occasionally, for the purposes of fishing and wild-duck shooting.
In the meadows about the Loddon and St Patrick's Stream in the spring time the beautiful fritillary or snake’e's head can be found growing in great abundance;  it is a most engaging flower, something between a wood-anemone and a tulip, generally of a brownish chocolate colour, with pale spots on it, but sometimes pure white;  this flower is admirably suited for the embroiderers' art, and I confidently recommend it to young ladies of a "crewel" disposition.

Snakes Head Fritillary
Snakes Head Fritillary

St Patrick's Stream, Loddon Drive Bridge

Footbridge St Patrick’s Stream
Footbridge over St Patrick's Stream

St Patrick’s Stream with weed 2004
St Patrick's Stream almost choked with weed in July 2004

St Patrick’s Stream tree
St Patrick's Stream is arboreally challenged, as is the punter!

St Patrick's Stream, George Leslie, 1881
St Patrick's Stream, George Leslie, 1881

St Patrick's Bridge

Over St Patrick's Stream close to its start on the Thames LEFT bank.
1887:  the Shiplake Miller complained that Patrick Stream eel-bucks pen up the stream.
1910: Sonning in Thames Villages by Charles Harper.

1920: Fred Thacker -

There is a persistent tradition that, before Shiplake weir was heightened and the lock built, penning the water above its previous level and so forcing it backward, the outfall called Patrick Stream was one of three infalls or mouths of the curiously lonely Loddon.
I notice on revisiting the spot in 1919 that the angle formed by the stream with the river is characteristic of a tributary, and not of a outfall.

2004: Graham Summer's description is going UP St Patrick's Stream (from the River Loddon from below Shiplake Lock into the Thames a mile above the lock. But he does recommend the reverse direction! -

You will be delighted to hear that St Patrick's Stream is not only punt-user friendly: it is one of the joys of punting the Thames.  At its head, [a mile above Shiplake Lock] there is a mini-weir that, in most water flows when a punter is likely to be afloat, has a drop of all of 3 inches which, if it threatens to impede the punter's progress, the punter crosses by initially standing at the back of the punt, and then moving to its front as soon as its centre has crossed the weir.

[ This entrance weir is about 100 yards down the stream from the Thames. The weir itself is submerged by a few inches and there is no drop (Summer 2011). It does not extend over the whole width. On the Right bank are strong piles which probably supported a gate in times past. ]
Graham Summer continued -

Thereafter, the Stream continues to be shallow, and moves fairly swiftly between open fields and frequently passes amongst trees whose lower branches only just clear the water. This means that the punt must be carefully steered to take the line of least arboreal resistance, and may require the punter to lie down at times (not merely for purposes of recuperation) to avoid being dragged overboard or, in any event, retained in the branches while the punt continues downstream on its own. The branches can in fact prove to be very helpful, as the punter can hang onto them while manoeuvring the punt with his / her feet. Some of the corners are quite sharp, but still easy to manage; and the flow of the Stream takes a lot of the hard work out of the descent.
Occasionally one encounters fisher-persons (you don't catch me being politically incorrect), but they are usually so surprised that their usual antipathy to punters seems to be in abeyance (although possibly it is because the winding nature of the Stream means that you are in sight for too short a period to permit them to react)..

Slightly more worrying were the frequent swans with young. In such a narrow stream it was hard to pass without upsetting them - and the swift stream gave no opportunity to bide ones time. You are armed with a pole or paddle - don't hit the swans - do what they are doing, make a display - splash and shout and they will back down ... probably ...

After what may be about half a mile, it is very difficult to tell with the twists and turns of the stream, you meet the faster, deeper (about 3 feet), and wider (about 20 yards) River Loddon. The Loddon has a firm bottom, and it flows from your right to your left (skiffers should note that punters look in the direction in which they travel).
If you are so minded, you will punt down the Loddon faster than you have ever punted anywhere, until it flows out into the Thames just opposite Shiplake Lock, and just upstream from the railway bridge.
The descent is not an experience to be missed by any punter going from Sonning to Shiplake - skiffers eat your hearts out (alternatively, if you do try it, let St Patrick's Stream scrape your bottom off)
I have used St Patrick's Stream on at least half a dozen occasions, most recently with my wife in July 2003 in our 2-foot racing punt, when the Stream was as I describe. The first occasion must have been in the late fifties, at a time when one could still hire a pleasure punt from St George and the Dragon at Wargrave. I hired such a punt, and - not knowing anything about the waterways in that area - I found the fast flowing Lodden and (you've got to show them that you are British) set off upstream.
When I reached the junction where faster water was rushing in from my right, I decided to see if I could shove the punt uphill against the flow, at times managing only a few feet per shove. After about half an hour I emerged unexpectedly into a wide and tranquil river that I could not identify with any certainty; and while "Dr Livingstone I presume?" seems to have acquired some notoriety, I am not sure if the same can be said of my words to people passing in a cruiser "Excuse me, is this the Thames?".
Much as I enjoyed the experience, my suggestion is that you descend the Stream.

2002: I quote, without comment, from my own log of a trip in 2002 -

As I was punting silently around one of the large bends in the river at this point I was skirting a large reed bed, leaving perhaps only a foot of clear water.  Suddenly I saw that the reeds had been neatly cut back and there was a step and cutting back in the reeds towards the bank.  I turned to look up this cutting and came face to er - face with a completely nude dark skinned man standing a couple of feet higher than me, about to dive into the river.  We were both so surprised we neither of us had time to react.  But I am definitely sure it was a man.

2020: Paddleboarder on St Patrick's Stream

Taking a stand-up-paddleboard trip along St Patrick's Stream (lacking the romance of the punt, perhaps, but currently a popular albeit less classy method of river travel) was trickier than I had anticipated. The Stream is rare in that it flows out of the Thames rather than into it; having failed to do the necessary research, I set off up the Loddon thinking that the Stream would bring me back to the Thames. After desperately struggling up the Loddon for at least half an hour, I was greeted by the unwelcome sight of St Patrick's Stream rushing towards me. An angler sitting on the bank, amusedly observing my annoyance, sardonically remarked that I had gone the wrong way, although 'The stream did used to flow the other way once.' So it turned out that I had arrived at the mouth of St Patrick's stream approximately 250 years late. This was no help to me. Getting back to the Thames took a paltry 5 minutes compared to the 30 it had taken to come up!