While strolling along the St. Paul waterfront in the late 1980s I came across a manhole lid upon which the words “Trout Brook” had been crudely spray-painted in fluorescent, orange letters. Scanning the riverbanks in the vicinity, I spied a cavernous sewer outfall, more than garage-sized, disgorging a multi-hued stream of water to the Mississippi River. I scrambled down the banks for a closer look.
The outgoing stream had the appearance of strong green tea, swirling in arabesques where it met the powerful brown river current. A good meaty sulfide aroma wafted over the water to my virgin nostrils. An unlikely place for trout, I remember thinking. Many people would have been revolted by this spectacle but I was strangely fascinated. Here was a stream flowing through the very heart of St. Paul and I had never seen it before. Psychologically speaking, it was as remote as one of Joseph Conrad’s literary rivers. Poking a convenient stick into the water at the outfall to check its depth, I resolved to get a flashlight and do a bit of exploring. This was to be one of my earliest ventures into the urban underworld. Little did I realize at the time that it would also be a voyage into St. Paul’s past, and times even more remote. Reaching the headwater lakes of the Trout Brook system was analogous, in a very minor way, to the Victorian explorers reaching the lakes at the headwaters of the Nile. This was a sort of subterranean Nile, with many little Egyptian motifs in the way of sewer architecture to spur interest.
St. Paul’s underbelly is well irrigated. Trout Brook is merely a side-branch of Phalen Creek. Cascade Creek flows under the West Seventh neighborhood. Battle Creek and Odell’s Creek flow under the East Side. Neighboring Minneapolis has several of its own.
Surface streams get buried and “lost” for a variety of reasons. Sometimes the motive is to hide what has become an eyesore, or to alleviate flooding. Sometimes the land on which the stream flows is needed for other purposes. Or sometimes, as in the case of Trout Brook, the streams were not buried per se, so much as that the adjacent street grade just grew upwards around them over the years.
In a very real sense, of course, the former surface streams are not “lost” since they are still flowing as lustily as ever. Indeed it would take a very expensive feat of engineering to get rid of them completely. To truly eliminate a stream you would have to fill the drainage basin, eliminating the topographic focus of the drainage. That could involve shifting many cubic miles of soil.
Some cavers have the notion that you can tell the difference between a boring old storm drain and the more exciting true underground stream by some special markings on the manhole lid. But the obscure art of interpreting the heraldry of manhole lids, alas, leaves much to be desired. What you really need is some good solid historical research. And tracing the pedigree of a pipe can sometimes be difficult.
One of the most salient topographic features of downtown St. Paul is the mile-wide gap in the white crescent of sandstone cliffs along the Mississippi River. City Hall stands on a full thickness of bedrock, but the sandstone thins out where Kellogg Boulevard goes downhill, finally to vanish from sight altogether before reappearing in all its glory at Dayton’s Bluff. Lowertown occupies the resulting gap. But what created this gap in the first place?
Geologists long ago surmised that this gap was carved by a pre-glacial precursor of the Mississippi, flowing down from the north. The Mississippi has changed course several times in the past million years or so and has only lately carved its present gorge. The topographic depression left by its precursor became the focus of postglacial drainage, and the stream that now runs through the gap is called Phalen Creek—together with its largest tributary, Trout Brook.
The Mississippi floodplain is a muddy place and was even more so back before engineers tamed the river. Imagine you were to direct a stream of water from the surrounding uplands down on top of all that mud and you get an idea what the early Trout Brook-Phalen Creek delta was like. No wonder it was described as “a bottomless bog” in Josiah B. Chaney’s classic essay, Early Bridges and Changes of the Land and Water Surface in the City of St. Paul. Published in 1908, Chaney is a wonderful reference for the vanished streams and lakes of old St. Paul generally.
Just trying to throw a road across this wetland was a Herculean task, as may be gleaned from the old City Council minutes. It was first proposed to grade East 7th Street across the morass in 1860 but it wasn’t until 1873 that the job actually got done. Bridging the streams required expensive stone arch culverts, the culvert for Phalen Creek costing twice as much as that for the smaller Trout Brook. These streams are represented in early, but now defunct, street names. Culvert Street was named after Phalen Creek, Brook Street after Trout Brook, and Canal Street for the combined stream below the confluence.
But something had to be done about the Lowertown wetland as a whole. In one of the most dramatic cut-and-fill jobs in municipal history, Baptist Hill, a mound of glacial debris 50 feet high, formerly located where Mears Park is today, was carted eastwards after the Civil War under the direction of city engineer David L. Curtice and dumped into the wetland. In the process, Phalen Creek and Trout Brook were left at their original, lower level—already well on their way to becoming subterranean.
While the Trout Brook-Phalen Creek valley was a curse to roads, it was a blessing for the railroads. On June 26, 1862, the steamboat Key City unloaded the first locomotive in Minnesota, the William Crooks, at St. Paul. Ask yourself, how would you go about getting this locomotive out of the deep river gorge, to speed it on its way to the town of St. Anthony, its destination? Perhaps hoist it up the sheer 80-foot cliffs with a crane? In the event, such heroic remedies proved unnecessary because of the stream’s gap in the sandstone bluffs. The train steamed up through the gap and rolled into St. Anthony, ten miles away, less than half an hour later.
Railroads have so dominated this valley ever since that the land between Phalen Creek and Trout Brook came to be known as “Railroad Island,” a sort of industrial Mesopotamia. Three roundhouses were built in the valley. A large railroad machine shop existed where the Pennsylvania Avenue exit of Interstate 35E is now located. So consistently did the railroad engineers favor the old streambeds to lay their tracks, to achieve the lowest possible gradient (the streams themselves flowing in tunnels below) that one caver joked that “Soo Line” was all but synonymous with “sewer line.”
Moreover, there’s another set of tunnels above the storm tunnels, built for the trains themselves, at a place called Westminster Junction. The Westminster Tunnel, with the date of 1885 carved into its keystone arch, is the classic railway tunnel of the Twin Cities, 1,100 feet long. Shady characters often hung around in these railroad tunnels, however, so I actually felt much safer walking through the storm drains under the Trout Brook valley, rather than along the tracks.
In 1893, city engineer George Wilson undertook the task of formally burying the lower reaches of the two streams, though several short segments had been roofed over years earlier. It was officially dubbed the Canal Street Sewer. We learn that the supposed “bottomless bog” actually did have a bottom after all, as “The length of piles below cut-off varied from 15 to 28 ft., at which point a hard gravel bed is struck.” With commendable thoroughness, the location of every one of those piles is noted in the old surveyor’s leather-bound fieldbooks, stored in the Public Works vaults to this day.
Wilson’s magnum opus still exists, and is easily distinguished by its innovative steel beam ceiling, Platteville Limestone rubble masonry walls, and granite floor. By far, however, the most endearing details are the “gargoyles”—curiously wrought iron spouts that vomit water into the tunnel. Wilson was so proud of his handiwork that in 1894 he published an article about it in Engineering News, and one of the accompanying figures became incorporated into sewer textbooks (though at least one of the textbooks misattributes it to Minneapolis). Wilson’s annual reports for these years contain classic photos of the project.
Wilson’s tunnels are large enough to drive a truck through and indeed something like that actually happened in August 1983, when during a heavy rainstorm, Lowertown flooded and a T-Bird was swept into the open channel segment along East 4th Street. The car ended up in the Mississippi, where for some days after, gawkers could get a glimpse of it resting peacefully on the bottom.
The Canal Street sewer, usually filled with waist-deep, stagnant water, is essentially a roofed-over bayou of the Mississippi, filled with the river’s backwater. Walking upstream from the river wearing a “poor man’s wetsuit” (street clothes), I could easily tell where the storm drainage met the actual river water by where my feet got tangled in the antler-pronged driftwood that spun about in the gloom. This was a “convergence zone” in the sewers—a place where two bodies of water, with different temperatures, mingled together, creating tunnel fogs.
By the time I came to explore it, however, the Canal Street sewer, already a century old, was showing its age. The underlying mud had pushed up the granite floor into slippery “whalebacks” which later split open, allowing the mud to wash out, leaving large erosional cavities in the floor, like a broken tooth. At other places, especially under leaks in the tunnel ceiling, there were “petrified sandbars,” where the lime minerals dissolved from the concrete above were redeposited by the dripping water onto loose sediments, cementing them firmly together into a solid, durable mass.
Excerpted from SUBTERRANEAN TWIN CITIES.