Is Winona Lake safe to swim in?

Whether Winona Lake is safe to swim in has a different answer in different weeks, so the useful skill is learning to look up the current one. For a lake of about 570 acres, Winona is unusually well monitored. The Lilly Center for Lakes & Streams at Grace College samples seven Kosciusko County beaches every week during the summer, Winona's public beach among them, and posts the results where anyone can read them.

This article walks through the two data pages that matter, explains the thresholds they cite, and covers the part the data pages leave out: the Town of Winona Lake, which operates the beach at Limitless Park, makes the actual open-or-closed decision. By the end you should be able to answer the question for yourself, any week of the summer, in about two minutes.

A worked example: the numbers on this article's check date

Read together, those results say the beach had elevated bacteria in mid-August, and that the open water carried a toxin level that matters for dogs but sits far below the human threshold, while the beach's own toxin test came back clean. What they do not say is whether the beach is open. A lab number by itself does not close the beach. Treat a high count as a reason to check the town's announcements before loading the car, and to wait for the next weekly sample. The sections below explain what each test measures, why the two are different, and why the numbers move around as much as they do.

What E. coli is and why the lake gets tested for it

E. coli is a bacterium that lives in the digestive tracts of warm-blooded animals, humans included. There are hundreds of varieties and only a few of them harm people, which is why its role in beach testing is mostly indirect: E. coli in lake water indicates that fecal contamination has reached the water, and fecal contamination travels with the pathogens that actually make swimmers sick. The Lilly Center's E. coli explainer covers the basics in more depth.

Around Winona Lake the plausible sources are the familiar ones: waterfowl such as gulls, ducks, and geese, livestock upstream in the watershed, human sources such as failing septic systems, and the storm drains that carry street runoff to the lake. As the Lilly Center's explainer puts it, "Rain collects E. coli from animal waste and disposes of it in the nearest body of water."

The health risks, per the CDC as summarized on that page, range from diarrhea and urinary tract infections to pneumonia and sepsis in serious cases. Children and adults over 65 are the most vulnerable groups, so a high count is a stronger reason to keep small kids out of the swimming area than to cancel an adult's paddleboard lap.

What CFU per 100 mL means

The unit on the E. coli page is CFU/100 mL: colony-forming units per 100 milliliters of water, a bit less than half a cup. The lab cultures each sample and counts the bacterial colonies that grow, and each colony traces back to viable bacteria in the original water. More colonies means more live E. coli in the sample. The page cites 235 CFU/100 mL as the EPA's safety threshold for recreational water, which puts the August 12 beach reading of 648.8 at nearly three times that line. For contrast, the other monitored beaches in the same reporting period ranged from 1.0 to 32.7.

Blue-green algae and microcystin: a separate test for a separate hazard

Blue-green algae, formally cyanobacteria, are organisms; microcystin is a toxin some of them can produce. The distinction matters because the Lilly Center's second weekly test measures the toxin itself, and because the two tests track different hazards that can move independently. A beach can post a high E. coli count with no detectable microcystin, which is exactly what Winona's mid-August snapshot showed, or the reverse.

For thresholds, the microcystin page cites IDEM, Indiana's environmental agency: 8.0 parts per billion for humans and 0.8 ppb for pets. The pet line sits at a tenth of the human one because dogs are at particular risk. They swallow lake water readily, and they lick algae off their fur after a swim. In the same August 7 reporting week that both Winona sites tested at none detected, Silver Lake measured 0.859 ppb, above the pet threshold, which shows how much this varies from one lake to the next.

For statewide context, IDEM's blue-green algae program runs its own sampling at selected state park swimming areas from Memorial Day to Labor Day, and its page notes the Lilly Center's county-level monitoring alongside it. The Lilly microcystin page updates weekly from June through August, with a fuller analysis published each October.

Why one number does not describe the whole lake

A beach sample describes the beach on the morning it was taken. The stream results posted alongside the beach data make the point: on August 7, Peterson Ditch, the inlet that drains farmland and neighborhoods south of the lake, measured 2,419.6 CFU/100 mL, while Eagle Creek, the lake's outflow, sat at 38.4. Water entering Winona Lake can carry many times the bacteria of water leaving it, with the lake diluting and settling what the streams deliver in between. Where you swim relative to an inlet matters, and the open water in the middle of the lake is a different environment from the beach shallows where samples are drawn.

Cadence matters too. In the Lilly Center's words, "We sample 14 streams every other week, all year round, and 7 beaches during the summer," and the E. coli page is updated weekly by its research team. Every posted number is a snapshot from a sampling day, and conditions can change between visits in either direction. The watershed page on this site maps the ditch systems behind those stream numbers.

Rain changes the numbers

The most predictable driver of a bad E. coli week is a storm. Winona Lake's watershed covers 18,730 acres by the Lilly Center's measure, and rain falling anywhere on it washes toward the lake through a handful of ditches, collecting animal waste along the way. That is the mechanism behind the Lilly quote above, and it is why a beach that tested fine on Tuesday can be a poor choice on Saturday if heavy rain fell on Friday. The next sample may not be taken for days, so after a big storm the freshest posted number can already be stale.

This site covers the runoff sequence in detail in what happens to Winona Lake after heavy rain. For current conditions and the five-day forecast, see Lake Today, and the timelapse page shows how quickly weather moves across the lake.

Who actually closes the beach

The Lilly Center publishes measurements. Closure authority sits with the Town of Winona Lake, which runs Limitless Park. The distinction played out in July 2025: on Tuesday, July 1, the town announced on its Facebook page that the Limitless Park beach was temporarily closed over high E. coli counts, as WSBT reported, and by Wednesday, July 2 it had reopened after health-department test results came back at safe levels. The whole closure lasted about a day.

As of this article's check date, August 17, 2026, I found no news reports of a 2026 closure at Winona Lake. Absence of coverage is weaker evidence than an official all-clear, so treat the town's parks page and its Facebook announcements as the deciding source, whatever the latest lab numbers show.

Before you swim: the short checklist

The routine for a swim day comes down to five habits:

• Check the two data pages. The E. coli results and the microcystin results, with 235 CFU/100 mL and 8.0 ppb as the reference lines.
• Check the town's announcements. The parks page and the town's Facebook channels carry any closure notice; the data pages do not.
• Skip swimming right after heavy rain. Runoff raises bacteria counts before the next sample can catch it, so give the lake a day or two after a big storm.
• Keep dogs away from visible scums. The pet threshold for microcystin is a tenth of the human one, and dogs both drink lake water and lick their fur clean afterward.
• Rinse off after swimming. Microcystin can cause harm when it is left on skin, and a freshwater rinse is a good habit after any lake swim.

Most weeks the routine ends in a swim. In the same mid-August reporting period that flagged Winona Lake Beach, the six other monitored beaches all came in far below the 235 line, and Winona's beach microcystin result was clean. A two-minute check before you drive over tells you which situation you have.