By Lizzy Reitzloff
Precipitation these past two months is twice as high as the historic ‘normals’ averaged from several weather stations across Jefferson County. Between May 20th and July 26th, an average of 16.78 inches of rain fell across Jefferson County, which typically sees roughly 8.55 inches during that period. Heavy precipitation equals more runoff, which has a significant impact on our local waterbodies.
Tim Sullivan: timothy.sullivan@apg-sw.com
Many Rock River Coalition stream monitoring volunteers have noted significant dips in oxygen levels in their streams following major rain events, with one recording levels as low as 0.08 parts per million (ppm.) Typical oxygen levels are 3.0-7.0 ppm. These low oxygen levels are, in large part, caused by heavy, repeated rainfall that carries organic materials from wetlands, agricultural fields and other types of land use to the watershed.
Heavy rains affect oxygen levels by washing nutrients, sediment, and organic matter (like sticks and leaves) into our creeks, which can result in chemical and biological fluctuations in the water body. As bacteria work to decompose the sudden flush of organic matter, they use up a lot of oxygen in the process. If low oxygen levels are widespread in a waterbody and fish are unable to find a refuge with higher oxygen levels, fish kills can occur.
Two such fish kills were recently announced by the DNR in mid-July, one on Buffalo Lake and another, on July 11, on the Yahara River by Stoughton. The DNR investigated the Yahara River the following week and found dead blue gill, largemouth bass, northern pike, white bass, bullhead, crappies, and other such fish between Highway B and the Stoughton Dam.
What caused these fish kills? Low oxygen levels. At the peak of this investigation, oxygen levels fell to below 2.0 ppm. Levels quickly recovered, returning to normal within two weeks. Local fish populations are not anticipated to be impacted long-term by this event.
When heavy rain wash nutrients off our landscapes and into our waterways it also feeds the algae within them, potentially triggering blooms, as seen in several of our local lakes. So far this year, the DNR has received 75 algae bloom reports, 40 of which were confirmed to be blue-green algae. These blooms can pose health risks to water enthusiasts that are exposed to it by inhalation, swallowing, or skin exposure, and are particularly dangerous for pets and kids, who do not know to avoid it.
In a recent press release, DNR warned locals to not boat, swim, wade, etc. in water that “looks like ‘pea soup’, spilled paint or water that has scum layer, mats or puffy blobs floating on the surface.” This water may have a blue-green algae bloom commonly associated with high levels of algal toxins, harmful bacteria, viruses or parasites that can induce vomiting, diarrhea, wheezing, skin irritation or rashes, depending on the type of exposure.
Read through this site for tips on navigating algae blooms to keep you and your loved ones healthy, and refer to this site for beach closures or advisories this due to unsafe conditions.
The DNR recently published a news release recommending that private-well owners test their water. As the article states, “flood waters and runoff contain bacteria and other contaminants that can affect private water supplies and cause the spread of waterborne illness.” Consult the information given in this news release if you’ve experienced any recent changes in the taste, color or sediment levels in your well water.
The widespread effects of the recent rain events are sure to be felt by all as we continue to navigate our lives this summer. Please take the necessary precautions to ensure you and your loved ones have a great rest of the year. If you’re interested in learning more details on our changing climate patterns and how they’re affecting southern Wisconsin, consider attending The Confluence, Rock River Coalition’s upcoming conference on Nov. 9 in Fitchburg, WI.
This year’s theme is “Stewarding the Rock River Watershed, Opportunities and Successes” and our keynote speakers will be covering the changes in climate patterns in the Basin in depth. Click here to register and learn more about The Confluence!