The La Crosse River - Medary
The tributaries of the Mississippi north of the Wisconsin include the La Crosse, Black, Trempealeau, Buffalo, Chippewa, St. Croix, and numerous smaller streams. The La Crosse River lies entirely in the Driftless Area and is the only one of these whose headwater region has been mapped in detail. The La Crosse River rises close to the escarpment at the edge of the Western Upland, the divide being narrow enough to be pierced by railway tunnels only a quarter mile long. It has a wide valley opened out in the weak Cambrian sandstone. It rises at an elevation of about 1000 feet, having a steeper grade in the headwaters than near the mouth. In the headwaters, above Sparta, WI, it descends at the rate of 13 1/2 feet per mile.
What is a river?
Most of the water you see flowing in rivers comes from precipitation runoff from the land surface alongside the river. Of course, not all runoff ends up in rivers. Some of it evaporates on the journey downslope, can be diverted and used by people for their uses, and can even be lapped up by thirsty animals. Rivers flow through valleys in the landscape with ridges of higher land separating the valleys. The area of land between ridges that collects precipitation is a watershed or drainage basin. Most, but not all, precipitation that falls in a watershed runs off directly into rivers - part of it soaks into the ground to recharge groundwater aquifers, some of which can then seep back into riverbeds.
Why is there flooding?
Flooding is a natural part of a river's cycle. The majority of the erosion of river channels and the erosion and deposition on the associated floodplains occur during flood stage. In many developed areas, human activity has changed river channel form, altering different magnitudes and frequencies of flooding. Some examples of this are the building of levees, the straightening of channels, and the draining of natural wetlands. In many cases human activities in rivers and floodplains have dramatically increased the risk of flooding. Straightening rivers allows water to flow more rapidly downstream increasing the risk of flooding places further downstream. Building on flood plains removes flood storage which again exacerbates downstream flooding. The building of levees may only protect the area behind the levees and not those further downstream. Levees and flood-banks can also increase flooding upstream because of back-water pressure as the upstream water has to squeeze between the levees.
River Classifications:
Youthful river: A river with a steep gradient that has very few tributaries and flows quickly. Its channels erode deeper rather than wider.
Mature river: A river with a gradient that is less steep than those of youthful rivers and flows more slowly. A mature river is fed by many tributaries and has more discharge than a youthful river. Its channels erode wider rather than deeper.
Old river: A river with a low gradient and low erosive energy. Old rivers are characterized by flood plains.
Rejuvenated river: A river with a gradient that is raised by tectonic uplift.
A little history on the La Crosse River
The La Crosse River Marsh is a wonderful example of a natural wetland. This type of wetland has a natural supply of water. In this case the level of the marsh depends on rainfall amounts as well as the level of the La Crosse River. Marshes also usually have a greater variety of animals and plants than do lakes, grasslands or forests. They have characteristic plants that grow in distinct zones or layers. The highest canopy of plants includes cattails. On the water surface are duckweeds, the world’s smallest floating plants, which are a great source of food for waterfowl. There are a lot of algae (much of it microscopic) between the water surface and the soil at the bottom.
According to the state wetland inventory, the La Crosse River Marsh is 1,077 acres and is included in the Mississippi River Floodplain. This kind of a marsh is called a riparian marsh because it occurs along a river. It is extremely important for many reasons including the fact that it absorbs excess water when the river level is high and releases water when the river level is low. This helps to prevent floods and droughts.
The La Crosse River originally had two channels. The northern channel left the main channel in the SW ¼ of Section 29 and meandered westward until it reached the Black River, near the present day junction of Milwaukee and Car streets. The northern channel flowed until approximately 1885 when it was obstructed and eventually eliminated by railroad business. The southern channel largely followed its current course to the Mississippi River except that the mouth emptied in farther south and inland. The southernmost channel dipped to a point approximately just north of where Front and Pine streets would intersect today. The southern portion of this river stayed in this channel until around 1885.
Silver Creek, an outlet of the La Crosse River, and the agricultural drainage ditch system were blocked by the construction of Lang Drive in 1932. As a result water began to slowly back up and the landscape went from a productive well-drained tillable area to marshland in the span of a decade or more.
The former Green Bay & Western railroad tracks purchased by the CB&Q in 1936 along East Ave. North and Oak Grove Cemetery were removed in 1959, while the former track embankments along with raised dike roads to city water wells in the marsh became part of the Myrick marsh RABBIT (River and Bluff Bicentennial Intra-City Trail) hiking trails constructed in 1976. The La Crosse River Marsh water wells were used by the city of La Crosse from 1912 – 1969. The wells were abandoned in 1969 due to excessive magnesium and iron deposits in the water.
A 1989 analysis of recreational use of the marsh indicated a wide variety of recreation: hiking, wildlife watching, biking, jogging, canoeing, skiing, fishing, photography, sketching, snow shoeing and trapping. The majority of users want to see more trails. The need for more recreation space was reiterated in the City's comprehensive plan of 2002 which sets as a goal: "Expand the trail system and trail connections particularly along the riverfront, the La Crosse River marsh and the bluffs."
To receive credit for this Earthcache, you must answer the following questions:
1) What is the descent rate of the river? Determine how much the La Crosse River descends in feet per mile.
At Waypoint 1 (CANOEM) walk down to the waters edge and take an elevation reading. Also mark your location, you will need this later. Next head to Waypoint 2 (CANOEG). When you arrive here walk down to the waters edge and take another elevation reading. Also note how far you are from the waypoint you marked in the first step. Using your elevations calculate how much the river descends in feet per mile.
(Note: If you were to hop in your canoe or kayak and travel the river from Waypoint 1 to Waypoint 2 the distance is 1.9 miles.)
2) What is the flow rate of the river? Determine the flow rate of the La Crosse River near the posted coordinates listed above in feet per second.
This can be done by measuring a length of the river, then watching something float by or tossing in a stick at the starting point. Using a stopwatch, calculate the time it takes to complete the measured distance. Now using that time, calculate into feet per second.
3) Referring to the River Classifications above, decide if the La Crosse River is a Youthful, Mature, Old or Rejuvenated River? Please explain why you chose this answer.
(Optional) Pictures are not required, but welcome. They are a great way show others where you have been and what to expect before arriving. Please post a picture of yourself or any river landscape near one or all of the waypoints listed below.
The location of the Earthcache is between the canoe access points along the river. Start at Waypoint 1 (CANOEM) and take your measurements. Now work your way to Waypoint 2 (CANOEG) to get the final measurements. The Earthcache coordinates are a viewing point along the La Crosse River on the Great River State Bike Trail. The canoe landings can be accessed with a vehicle. There are two bridges that cross the river between the canoe landings. Both of these bridges are along bike trails. The best way to see this Earthcache up close would be with a canoe or kayak, they are not needed to complete this Earthcache.
The Geocache Notification Form has been submitted to Jordan Weeks of the Wisconsin DNR. Geocaches placed on Wisconsin Department of Natural Resource managed lands require permission by means of a notification form. Please print out a paper copy of the notification form, fill in all required information, then submit it to the land manager. The DNR Notification form and land manager information can be obtained at: (visit link)
References:
La Crosse Public Library
Murphy Library, UW-La Crosse
