A View into the Watershed of the Mississippi River
The watershed that my hometown is in is the Mississippi River Watershed, the 3rd largest watershed in the world. With the grandiose of the river, it has many eyes involved in keeping the people and species that rely on it protected, as well as many risks to bringing the quality of this watershed down.
Looking at the report of groundwater and surface water quality from the Minnesota DNR, there were several findings listed. The groundwater quality overall appears to be healthy, with few exceptions of chemicals of interest and concern. The three chemicals that were in excess for human consumption were arsenic, nitrate and chloride for drinking water standards. Arsenic is natural forming and comes from mineral deposits, but is dangerous for human consumption. Nitrate is attributed to the presence of clay deposits which gives risk to blue-baby syndrome in babies under the age of 6 months. Finally, chloride was largely in excess to the abundance of salt running off into the watershed, which changes mostly the taste of drinking water.
The surface water had several concerns as well. The primary impairments were insufficient dissolved oxygen in the lakes and mercury in the fish tissue. The lack of dissolved oxygen came mostly from algal blooms accumulated from nitrogen and phosphorus runoff. The mercury was of larger concern because the consumption of the fish with higher mercury content gave rise to risk in damage to the central nervous system. According to this report, 70% of mercury deposition in Minnesota is anthropogenic. The solution has been to reduce this. The state is looking on reducing the mercury concentration emission by 93%. As for the algal blooms, they were able to track how much soil erosion and runoff occurs and to try to reduce that.
Finally with this comes concern over invasive species. The one that seems to be the greatest in threats ecologically to this watershed is the presence of Zebra Mussels. They have drawn water into their bodies and filtered out most of the suspended microscopic plants, animals and debris for food. This leads to depleted food supply for native organisms and has killed a great number of species. All in all, these issues can be reversed, but great work needs to be done.
Citations:
https://www.pca.state.mn.us/sites/default/files/wq-ws1-12.pdf
I found it very interesting how zebra mussels can still colonize fast moving rivers. I agree that mercury accumulation is a daunting contaminant for a watershed, given its human health effects and its effects on wildlife. How does Minnesota plan on reducing mercury emissions by 93%, since that is a very ambitious figure? Also, do you think that fertilizer leaching into groundwater aquifers is another reason why nitrate is found in the groundwater of your watershed?
ReplyDeleteCases of mercury found in fish are very scary, especially to fishermen. Minnesota is the state of 10,000 lakes and fishing is a common hobby there so high cases of mercury can affect both human health and wildlife. I wonder how Minnesota plans to tackle the algal bloom issue along with much of the other natural problems. How does Minnesota plan to reduce each of the chemicals’ in the groundwater?
ReplyDelete