They Reversed the Chicago River

On November 19, 2008 · 0 Comments

What’s a growing city to do when its water supply is jeopardized by its own filth? If it’s Chicago and it’s the late 19th Century, they reverse the flow of an entire river system and purposely puncture a Continental Divide in the process.

I’m in Chicago this week so I wanted to make sure I got away from work for a few moments to explore a little local geo-history, the great Chicago Sanitary and Ship Canal. Most visitors stop by Grant Park, the Navy Pier, the Magnificent Mile and places like that. I, on the other hand, pay homage to the remnants of an open sewer. The city still dumps treated wastewater into the Chicago River system, but no doubt to the delight of visitors that take those tour boats through its skyscraper canyons, it’s a whole lot cleaner than what got sent through here a century ago (Dave Matthews not withstanding).

Chicago River at State Street
The Chicago River flowing through downtown Chicago from the State Street bridge, looking east

The Chicago River extends 156 miles. It once flowed east through the city and into Lake Michigan, taking raw sewage and whatever else got thrown into it away from a growing population. This caused a dilemma: Chicago also got its drinking water from the lake. Besides the awful visual image this conjures, this had the potential to become a major health issue. So in 1887 the government decided upon a solution: they would simply reverse the direction of the Chicago River and flush their troubles away from the lake, thus separating their toilet from their drinking water. Sewage would be forced to travel in the opposite direction from its natural flow through the marvels of civil engineering. It would drain instead into the Des Plaines River, using a series of locks, canals, dams and pumps where it would travel far, far away. A 28-mile waterway, a massive undertaking known as the Chicago Sanitary and Ship Canal, opened in 1900 to much fanfare and critical acclaim to complete this honorable mission. That is, of course, for the citizens of Chicago. I’m sure the people who lived downstream in the other direction were less thrilled.

Engineering marvel aside, there’s another extremely interesting aspect of the local geography. A low ridge runs parallel to Lake Michigan about a dozen miles west of Chicago’s lakeshore. It’s the remnants of an ancient beach dating back to the end of the last ice age of 12,000 years ago. That’s all that separates two vast drainage areas: the Great Lakes / St. Lawrence basin that empties into the Atlantic Ocean and the Mississippi River basin that flows into the Gulf of Mexico. Nowhere else is it so easy to travel between those two massive waterways. Towns grew here and became prosperous simply because of the easy portage. An early passage, the Illinois and Michigan Canal, replaced the land-based portage. The Chicago Sanitary and Ship Canal took it one step further by actually removing the entire Chicago River watershed from the Great Lakes drainage basin and adding it to the Mississippi basin. In addition to the sanitation it provided to the city of Chicago, it served another vital purpose, the only navigable link between two hugely important commercial waterways.

To understand how little separates the Great Lakes from the Mississippi system, take a look at the Google Street View Image and you may be able to discern the slight rise that separates the two.

View Larger Map

Are you having trouble spotting it? That’s exactly the point. Contrast that with another continental divide I’ve featured previously. It quickly becomes apparent why this area on the southwest corner of Lake Michigan became so vital to trade and transportation.

This spot came to my attention from the Oak Park Tourist website, specifically from their series of pages on the Oak Park Continental Divide.

The terrain in our Village is so flat that the slopes are difficult to perceive. The best place to see a distinct drop off in both directions is at the northwest corner of Taylor Park, at the intersection of Berkshire and Elmwood. There you will be standing on the continental divide. At the time this area was first settled, the land east of Oak Park, being an old lake bottom, was mostly swamp. Our low ridge was the first high land west of the Lake and was a desirable place to build. Thus Oak Park’s first settler, Joseph Kettlestrings, in 1837 chose to build west of Oak Park Avenue, on top of the ridge. The oak trees, growing on the sandy ridge, gave Oak Park its name.

As a final thought, there are pressures to separate to two watersheds and return the Continental Divide to its original condition. This is for a couple of reasons. First, given the finite nature of the Great Lakes, there are concerns about the amount of water being drawn off for purposes other than drinking (i.e., as a giant toilet flush down the Mississippi). Second, there are anxieties that linking the two large systems will hasten the spread of invasive species through even greater territories of the United States.

Satisfied with my tourist excursion up State Street to the river, I returned to work.

Trail Ridge Road

On May 12, 2008 · 1 Comments

As covered in the prior post, Trail Ridge Road reaches stratospheric elevations as it becomes the highest continuous highway in the United States, cutting straight through the splendor of Rocky Mountain National Park. Visitors climbing the summit from Estes Park, Colorado encounter another noteworthy feature along this remarkable road after they pass the highpoint and the Alpine Visitor Center, heading downhill. At Milner Pass the highway crosses over the Continental Divide.

Trail Ridge Road, Rocky Mountain National Park
Source of map: United States National Park Service;

In truth there are several continental divides in North America. Some are specific to the United States and some to Canada, with others shared in common. The best known of these is often called the Great Divide, a physical contour separating east from west. Water on the eastern side will flow either to the Gulf of Mexico or the Atlantic Ocean. Water on the western side will flow to the Pacific Ocean. When the term "Continental Divide" is used without qualifiers it generally means the Great Divide, and that’s the famous line crossed by Trail Ridge Road at an altitude above 10,000 feet.

Milner Pass Sign

Continental Divide

Milner Pass elev. 10,759

The "Great Divide" separates drainage to the Atlantic from drainage to the Pacific. It traverses America from Alaska almost to Cape Horn.

Atlantic Ocean drainage [arrow pointing left]

Cache La Poudre Creek drains into the Platte River which flows to the Missouri, then to the Mississippi, thus reaching the Gulf of Mexico (part of the Atlantic Ocean).

Pacific Ocean drainage [arrow pointing right]

Beaver Creek drains into the Colorado River, which then flows through Grand Canyon National Park and on to the Gulf of California (A part of the Pacific Ocean).

Thus, there are two remarkable geographic features in a short stretch along Trail Ridge Road: the highest point of contiguous highway in the United States; and the boundary that marks the Great Divide. Along with that comes some of the most incredible Rocky Mountain scenery imaginable, worth a journey all on its own.

Canada Draining to the Gulf of Mexico

On January 17, 2008 · 1 Comments

Several distinct continental divides cross through Canada. Water flows eventually to one of five different bodies of water depending on its point of origination. Huge portions of Canadian territory rest within watersheds that drain to the Atlantic, Pacific and Arctic Oceans, and Hudson Bay. However one small corner of Alberta and Saskatchewan, barely 20,000 square kilometers, less than two tenths of one percent of the Canadian landmass drains down to the Gulf of Mexico.

Canadian Drainage Basins and Watersheds

The Atlas of Canada provides both a greatly detailed map and an inventory of drainage basins and their associated river watersheds. It lists only the Milk River, Frenchman River, Battle Creek and Lodge Creek as part of the drainage basin that leads eventually to the Gulf of Mexico. These are all a subset of the Upper Missouri River that flows towards the Mississippi River.

View Larger Map

The Frenchman River flows through the western portions of mixed prairie grasslands that have been carefully preserved within the western portion of Grasslands National Park. It courses through towns like Eastend, “located in the middle of nowhere and miles from the nearest city.” Local citizens have proclaimed this section of the Frenchman River watershed as Dinocountry and constructed the T.rex Discovery Centre as a primary attraction. It was near here that “Scotty” the Tyrannosaurus Rex skeleton was unearthed in 1994.Water flowing from these selected grasslands of southern Alberta and Saskatchewan depart Canada to traverse the entire length of the United States and terminate at the mouth of the the Mississippi River beyond New Orleans. This tiny sliver of Canada represents the far northern extreme of the Mississippi River basin. If a slight breeze caused a drop of water to fall onto the other side of the continental divide it would instead travel through the Nelson River watershed and eventually reach Hudson Bay. Fate determines whether a droplet flows towards one body of water or another, separated by more than 3,000 kilometres.

Source of Canada Drainage map: Wikipedia, as released to the public domain
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