21 February 2022
Coastwatch GLERL NOAA imagery December 17, 2021 (annotated).
Several years ago, when our kids were young and at least one was still in elementary school, I visited a class of 3rd graders taught by a friend of the family’s and put on a soil erosion demonstration. The “show and tell” consisted of setting up rainfall simulators for two contrasting land cover types represented by two baking pans: one filled with not quite two inches of bare soil from our back yard and the other filled with a slab of turfgrass with roots and soil cut from the edge of our backyard garden.
The rainfall simulator was an aluminum pie pan with numerous small nail holes punched through the bottom. The trays were set on a table with a book (covered in a plastic bag) propping one end of the tray to create a sloped surface. Enlisting the help of a couple of the students, one held the rainfall simulator (pie plate) a foot or so above the land cover model (soil or turf+soil baking pans) while another slowly poured water from a pitcher into the perforated plates to mimic rain.
The rain showered down onto the bare soil and ran by “overland flow” to an outlet cut at the low end of the pan and into a clear plastic ice cream bucket. The runoff from the bare soil tray picked up a lot of soil and the brown muddy effluent collected in the receiving bucket. Next, we did the same thing with the grass-covered soil. This time, less water ran off to the bucket and it was only slightly turbid.
Cover crops can help.
A wetter than average year in 2021, coupled with insufficient areas planted with cover crops probably contributed to higher than average sediment loads in lakes and rivers. Data recorded at Toledo Express Airport and available at Weather Underground indicate two days of heavy rain: 0.88 inch on December 6 and 0.87 inch on December 11, within two weeks of the date the above MODIS image was shot. The suspended sediment shown in Lake Erie and Lake St. Claire strongly contrasts with the darker, more transparent water in Lakes Huron and Ontario.
Higher sediment loads mean water treatment is more expensive. According to an article from our local weekly newspaper reporting on a recent Deerfield, Michigan village council meeting, “the quality of the raw water taken into the plant to treat has been very different all year round and in the last several weeks has required more treatment…This has been caused by more turbidity in the water and sometimes the need for more chemicals to be used in the water filtration plant.” The water plant operator claimed they’ve used a month’s worth of chemicals in two weeks (The Advance, Volume 148, No. 43, January 12, 2022).
More sludge from the filtration plant also means more to be disposed of, at a higher cost.
The Soil Health Nexus Work Group is comprised of scientists from 12 Land Grant Universities across the 12 state Northcentral region to “address the challenges of increasing access to soil health research, knowledge, extension and resources.” As part of their outreach and communications, the Group regularly posts online presentations through its Soil Health Nexus Digital Cafe Series.
In a presentation by Joel Gruver of Western Illinois University, “Solar Corridors for Soil Health” a national cover crop map reveals the recent percentage of crop land planted in cover crops was less than 10 percent in Michigan, Ohio, Wisconsin, Indiana, Illinois and Minnesota. This needs to change. Maryland leads the nation at 29 percent, due to financial incentives to protect fresh water supplies and Chesapeake Bay.
In the Midwest and Northeast, a trend toward more extreme precipitation events is clearly revealed in climate data, according to the Great Lakes Integrated Sciences and Assessments group at the University of Michigan. Unless real on-the-ground improvements are made, particularly on crop land, it looks like a lot of folks are going to be paying more for water.