Water flows from the higher elevations of the northern United States to our low-lying wetlands. Surface elevation, on average, decreases from the northern border with Canada all the way to the mouth of the Mississippi River. What that means is that most of the water that falls between the Rocky Mountains and the Great Smoky Mountains drains into the Mississippi and eventually in the coastal waters of Louisiana. We call this area the Mississippi/Atchafalaya River Basin (MARB) or the Mississippi River Watershed.  A watershed, by definition, is an area that drains to a river or lake. The Mississippi River Watershed encompasses nearly 41 percent of the United States.
Streams and ponds in the higher elevations of our watershed are fed by precipitation (rain, snow, hail, etc.) or springs. Water always follows the path of least resistance, which is downhill. Even on gradual slopes, water will seek out lower elevations. Flow rate is dependent on the angle of the slope, also called the elevation gradient. This explains why rivers in more mountainous regions flows faster than in our very flat land. Of course, some water will evaporate, some water will seep into the ground, and the rest will continue downstream until it gets to the ocean. While there are some exceptions to that rule, such as the Great Salt Lake in Utah and other Endorheic basins (no outlets besides evaporation), most water that falls on land will follow the water cycle that we all learned in grade school.
In Louisiana, the MARB outlets are the mouths of the Atchafalaya and Mississippi rivers and their distributaries. Because the state receives this water runoff through our bayous and marshes, so too does it collect the trash and other pollution from the watershed. This pollution includes not only typical litter and non-point-source runoff, but also agricultural runoff that carries an abundance of nutrients. Select groups across the state are employing litter collection traps in bayous and streams to prevent trash from ending up in our coastal waters. More about these issues can be found in our articles about hypoxia stress and soil pollution.
The International Day of Action for Rivers will be celebrating healthy watersheds worldwide tomorrow, March 14.  We encourage our readers to do a little cleaning in their local waterways year-round but especially tomorrow. There are several groups around the state who organize clean-ups in our local waterways for any who are interested. Some of these groups can be found in our sources. As the third largest watershed in the world, the MARB supports numerous ecosystems and human settlements, and it is crucial that we keep it healthy for all its constituents. Each day, our coastal wetlands protect our cities and ports, so we at CWPPRA strive to return the favor and #ProtectOurCoast.
Featured image from http://www.bayouvermilionpreservation.org/photos.html
City of Lafayette: http://www.lafayettela.gov/EQ/Pages/Environmental-Outreach.aspx
Bayou Vermilion District: http://www.bayouvermiliondistrict.org/