SOLDIERS GROVE - It was a beautiful May morning on the shores of Myrtle Lake in the old downtown area of Soldiers Grove on Sunday morning. BMW motorcycle riders were moving around, packing up and swapping those last stories about all the great rides they’d had over the past week.
Also in the park were Omaru Heras Ornelas of Crawford Stewardship Project (CSP), and Justus Benson and Randy Swiggum of the Swamp People’s Project (SPP). The three were assembled for a training, and water-quality sampling event.
The work is part of an ongoing effort by the groups, in partnership with Wisconsin Department of Natural Resources (WDNR) to monitor water quality on the lake, and identify what problems the groups may need to address in their efforts to restore it. In addition to the sampling, the group plans to remove algal growth from the lake, and has been involved in ongoing fundraising efforts for their restoration activities.
“As a kid growing up in Soldiers Grove, there was a place we called ‘the slough,’ which is a small, three-acre, spring fed pond full of biodiversity and life,” Randy Swiggum remembered. “That lake provided adventure, discovery, and natural education to all those who visited there, young and old.”
Swiggum said that over the years, due to the overwhelming amounts of runoff ladened with nitrates, phosphates, and other human pollutants, the slough has been going through the process of degradation.
Swiggum said that after an attempt to tackle the problem back in the mid 90s stalled, the slough, by then dubbed ‘Myrtle Lake’ by a local resident, was left largely unchanged and still at the mercy of the runoff and pollution.
At the Soldiers Grove Village Board’s April meeting, Benson had updated the board about water quality sampling results to date for the lake.
“We are uploading our sampling data, and this had allowed our data to be correlated with satellite water clarity readings,” Benson said. “What we have found is very high levels of phosphorous, and high e-coli levels after a rainfall.”
The reason the three were there on Sunday morning is because their sampling was being coordinated with the time the satellite moved over the lake. One of the many things recorded by water quality sampling volunteers is water clarity. Timing their sampling to coincide with the satellite allows the results to be compared.
‘Secchi’ sampling, a measurement of water clarity, will be measured by the group monthly from April/May through October. The device used to measure water clarity, a ‘Secchi Disk,’ is a thin round disk, attached to a rope. The surface of the disk is divided into four wedges, alternating in black and white.
The device is dropped into the water, and pulled up until samplers can see it – this measures the transparency of the water. The measurement is done twice each time sampling is conducted, and then those results are added together and divided by two, which gives the average.
Phosphorous sampling is conducted in April/May, June, July and August. There are different types of phosphorus that can be measured in a water sample, but samplers measure all of it collectively (the total phosphorus). Phosphorus concentration is another measurement used to estimate the lake’s Trophic State Index (TSI) score.
Chlorophyll in the water is sampled in June, July and August/early September. This is a measurement of the concentration of algae in the upper layer of the lake. The concentration of chlorophyll-A is usually lowest in cold, deep, or nutrient-poor lakes, and highest in warm, shallow, or nutrient-rich lakes. This is one of the measurements used to estimate the lake’s Trophic State Index (TSI) score.
Temperature profile and dissolved oxygen are sampled in April/May through September. Readings will be taken at different levels to determine temperatures at different depths. One of the things identified in some lakes is a ‘thermocline,’ The thermocline can be found by looking for an abrupt change in water temperature. A thermocline rarely develops in lakes less than 12-feet deep. If present, the depth of the thermocline is influenced by many factors, including a lake’s size, shape, and depth, and even the topography of the surrounding landscape.
A lake with low dissolved oxygen means the lake is losing oxygen due to decomposition of organic matter, and this process is consuming oxygen faster than it can be replenished.
Trophic State Index
A trophic state index (TSI) score places a lake into a category of oligotrophic, mesotrophic, eutrophic, or hypereutrophic. Lakes naturally occur in each of the first three categories, but hyper-eutrophic lakes are within that category because of human-caused nutrient enrichment. Below is a short description of each category.
Oligotrophic lakes are generally very clear, deep, and cold. The lake substrate is typically firm and sandy. Nutrient levels are low, so the lake generally does not support large populations of aquatic plants, animals, or algae. The fish that occur in oligotrophic lakes are often low in abundance, but large in size.
Mesotrophic lakes contain moderate amounts of nutrients, and contain healthy, diverse populations of aquatic plants, algae, and fish. Occasional algae blooms may occur. If the lake is deep enough to stratify, parts of it can become low in oxygen by the end of summer, and may result in some phosphorus release from the sediments.
Eutrophic lakes are high in nutrients and contain large populations of aquatic plants, algae, and fish. The lake bottom is typically soft and mucky. The aquatic plants and algae often grow to nuisance levels, and the fish species are generally tolerant of warm temperatures and low oxygen conditions. Common fish species include carp, bullheads, and bluegills.
Hyper-eutrophic lakes are very high in nutrients, and often exhibit large algae blooms, which may include dangerous levels of blue-green algae. Fish communities in hyper-eutrophic lakes are dominated by carp and other species that can tolerate warm temperatures, and low oxygen conditions. Most hyper-eutrophic lakes are small impoundments of streams, and fed by large watersheds composed of urban and/or agricultural land uses.
Citizen Lake Monitoring
The Myrtle Lake effort is part of WDNR’s ‘Citizen Lake Monitoring Network.’ The goals of the project are to collect high quality data, to educate and empower volunteers, and to share this data and knowledge.
WDNR uses satellite images to retrieve water clarity data for lakes across the state. This effort began in 1999 when UW-Madison Environmental Remote Sensing Center (ERSC) developed a model for the retrieval of water clarity data from satellite images and Citizen Lake Monitoring Network volunteers provided on-the-ground Secchi data to calibrate this model for each satellite image.
The results are uploaded to the WDNR Surface Water Integrated Monitoring System (SWIMS) lakes database by the water quality-sampling volunteers. This data is useful to employees at WDNR, and can also assist groups like the Swamp People Project when they apply for grants to help fund their projects. The data also provides information needed to know what kind of steps should be taken to restore the lake for public use.
• Crawford Stewardship Project will hold their annual ‘Love the Land’ fundraiser in the Soldiers Grove Village Park on Friday, July 1, from 5:30 p.m. to 12 a.m. The event will offer music from the Freaks of Nature, DJ Murder and Kween, food, beer, information booths and a silent auction.• Swamp People Project will hold their annual music fundraiser in the park on October 1. The event, as always, will offer music, food, beverages, speakers, information booths, and various auctions and raffles. Since their fundraising efforts kicked off in 2020, the group has raised $15,500 to clean up the lake and restore it for community use.