Lake Darling continues to fight bacteria problems after $12M restoration
Lake Darling near Brighton in southeastern Iowa has battled bacteria problems despite a $12 million restoration. (Photo courtesy of the city of Washington)
Lake Darling has posted one of the highest numbers of swimming advisories in Iowa in recent years despite a $12 million restoration finished in 2014.
This week, Darling violated three state swimming standards in a single round of tests, a rarity in the Iowa Department of Natural Resources’ weekly state-park beach monitoring program. Seven lakes had “swimming not recommended” warnings headed into the holiday weekend: Darling, Prairie Rose, Pine Lake South, Union Grove, Keomah, Rock Creek and Backbone.
An analysis by the Iowa Environmental Council found Darling, near Brighton, had 30 beach advisories for fecal bacteria and nine for algae toxins between 2014 and 2020. Only 10 of the 35 lakes tested had more advisories, led by Backbone Lake near Strawberry Point with more than three times as many.
Nine beaches had more algae toxin postings than Darling in that period.
The resources department has considered Darling a high point in Iowa’s perennial lake-improvement program. DNR in 2007 published an article headlined, “Lake Darling: A snapshot of success.”
The article included before and after photos showing how water clarity had improved. DNR noted that the lake, built in 1950, shrunk from 305 acres to 267 acres before it was drained and restored. Named for the famed Des Moines Register cartoonist and noted Iowa conservationist J.N. “Ding” Darling, the lake had landed on the state’s list of waterways violating water quality standards in 1998. In 2002, high bacteria levels meant the lake didn’t meet state standards for swimming.
The restoration and work on surrounding farmland over the years has cut soil runoff to under 7,000 tons a year from a high of 16,000 tons, DNR reported. The state also has supported plantings on local farms to reduce runoff, constructed water control basins and worked with pork producers to ensure proper manure applications.
Tests run by DNR beginning in 2003 found bacteria in the lake was mostly from animals. The area has a heavy concentration of hog confinements.
Both the bacteria and the algae toxins can give people, especially those with weakened immune systems, intestinal and other illnesses. Concentrations of the bacteria and toxins can vary by the hour.
DNR spokesman Alex Murphy said he was seeking comment from parks officials, but many were off Friday for the holiday weekend.
Seven state-park beaches post warnings this week
Seven state park beaches are posted with “swimming not recommended” signs after tests on water samples from earlier this week found high levels of fecal bacteria or algae toxin.
Bacteria readings exceeded state standards in Prairie Rose near Harlan; Union Grove near Gladbrook; Backbone near Strawberry Point; Keomah near Oskaloosa; and Darling near Brighton. Algae toxins exceeded standards at Pine Lake South near Eldora; Rock Creek; and Darling, where the reading was nearly triple the limit.
The number of warnings jumped this week from the several per week that were issued before recent rains increased runoff.
Alicia Vasto, associate water program director for the nonprofit Iowa Environmental Council, said an increase in microcystin, the main algae toxin, has been a concern.
“The pace is slower on E. coli (bacteria) advisories than previous years, but microcystin is on track to be really high,” Vasto said. “This is earlier in the season than we would typically see a lot of microcystin advisories, so having three in one weekend in early July is a lot. Precipitation patterns and the drought can make it difficult to draw conclusions, so we’ll have to see how the rest of the summer goes.”
The week before, three beaches, Backbone, Darling and Keomah. had bacteria warnings and Darling had a posting for the algae toxin microcystin.
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