I could be wrong but I don't think that the Rea has ever carried much water , except in flood conditions. However there was a millpond that was engineered for the Heath Mill/Coopers Mill in Floodgate Street. The weir made there formed a mill pond with the mill and head race draining off at Fazeley Street...just below the River Street junction. The weir backed up the Rea to above Digbeth bridge and would have formed a kind of reservoir there for rowing on. The owner of the mill had to sign a covenant not to back the river up too much because traffic would be disrupted at the Derritend bridge. The Westly Aspect shows all of this and the horsemen are standing on River Street and the angler is fishing in the mill pond.
The mill pond was eventually filled in and Gulverton Tin Works was built on top of the filling. The delapidated tin works is still there I think and the Rea runs along side of it in a deep manufactured channel...still open under Fazley St. and then under the canal to emerge at Montague Street at the point of the recently posted sketch.The run of the Rea now in that place is not a natural one. The natural path would have been further north from the flood gate and would have passed by Warwick Wharf I thnk...the wharf and canal not being there at the time.
Two views included; one of Westleys aspect and the other of the view today. Same building I am pretty sure but much modified. Fazeley Street and River Street.
In the Westley picture you can see the original run of the Rea just above the fishermen. At that point it would have just been carrying water that ran over the flood gate...the rest of the water going over the tandem mill wheels which can be seen. This is all eerily recognisable today...even the Montague Street sketch and one wonders if a dig on the side of the bridge in Fazely St. would not discover a mill stone. Being heavy, they would probably have just been buried when any demolition took place
I have been digitising some of Brunel's Contract drawings for the Birmingham and Oxford Junction railway held at The National Archive in Kew as part of research into the Duddeston Viaduct.
The original drawings are in a sorry state sadly having been poorly stored for several years before being handed over to the TNA. Many are on vellum and linen paper and have become very brittle.
One of the first to be completed covers the section around Heath Mill Lane/Great Barr Street/Liverpool Street northwards toward the Rea crossing and the link will display with north to the left.
https://images.birminghamhistory.co.uk/coppermine/displayimage.php?album=lastup&cat=10449&pid=11128#top_display_media
The second file is a scrap from the Society for the Diffusion of Knowledge map for the same area and tilted in roughly the same viewing plane
https://images.birminghamhistory.co...=lastup&cat=10449&pid=11127#top_display_media
Brunel's survey would have taken place around 1845-6 when the Act of Parliament was presented and therefore compares in time to the SDUK map which was produced around the same time and shows the course of the "Little Rea" leading away from the Mill Pool north eastwards.
Brunel's survey also shows a similar line feature appearing north of the Warwick Canal and heading in the same alignment as the present Montague Street.
The line itself snakes across the area, tiptoing past established factories with many of the abutments still in situ marching across the "small gardens" that bordered the rivers.
At this time the part of Montague Street beginning at Great Barr Street is only titled as "Proposed New Street" but nevertheless determined the many complex skewed arches that were constructed in the now lost section toward Curzon Street.
So if Rupert's buried millstones are to be found my bones tells me they will be around or beneath the Council Car Park but they could be quite deep down.
The main section of the River Rea is 6.5 feet lower than the base of the canal so if the original alignment of the Little Rea was culverted it will be beneath the base of the canal.