{"id":257685,"date":"2026-08-02T12:55:11","date_gmt":"2026-08-02T12:55:11","guid":{"rendered":"https:\/\/www.newsbeep.com\/us-pa\/257685\/"},"modified":"2026-08-02T12:55:11","modified_gmt":"2026-08-02T12:55:11","slug":"unpredictable-algal-blooms-keep-blue-marsh-on-alert-pottsville-republican-herald","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us-pa\/257685\/","title":{"rendered":"Unpredictable algal blooms keep Blue Marsh on alert \u2013 Pottsville Republican Herald"},"content":{"rendered":"

The main beach at Blue Marsh Lake Recreation Area in Berks County shimmered under the sun, the water clear enough to see the sand below. But upstream, in one of the lake\u2019s shallow northern arms, park ranger Brianna Treichler traced her finger along a thin scum line gathering at the surface. It was a subtle indication that harmful algal blooms may be lingering below \u2014 a reminder of why the lake stays under a year\u2011round advisory.<\/p>\n

Although the swim beach has tested clear this season, Blue Marsh remains under a lakewide harmful algal bloom advisory because conditions vary dramatically across the reservoir. In the northern arms, where warm water, slow currents and nutrient\u2011rich runoff collect, cyanobacteria can persist below the surface or gather in small patches that don\u2019t always reach the beach. On busy summer weekends, thousands of visitors swim, paddle and fish at Blue Marsh, often unaware of how quickly conditions can change.<\/p>\n

\"U.S.<\/p>\n

U.S. Army Corps of Engineers ranger Brianna Treichler highlights algae buildup near the bank, noting that cyanobacteria can move within the water column and appear suddenly after nutrient pulses. (AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

\"Calm<\/p>\n

Calm water and dense summer foliage frame Blue Marsh Lake, where year\u2011round HAB advisories remain in place. (AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

\"Water<\/p>\n

Water appears greener where Tulpehocken Creek and Northkill Creek meet the lake\u2019s main stem, a mixing zone rangers say can carry higher nutrient loads. (AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

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U.S. Army Corps of Engineers ranger Brianna Treichler highlights algae buildup near the bank, noting that cyanobacteria can move within the water column and appear suddenly after nutrient pulses. (AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

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\nThe biology behind the blooms<\/p>\n

Harmful algal blooms (HAB) aren\u2019t actually algae at all. The green streaks and surface scum that appear on lakes like Blue Marsh come from cyanobacteria: microscopic organisms that occur naturally in nearly every body of water in the world. By themselves, they\u2019re not harmful.<\/p>\n

The problem begins when warm water, sunlight, and nutrient\u2011rich runoff create the perfect breeding ground for cyanobacteria to multiply. Under those conditions, cyanobacteria can produce cyanotoxins, the compounds that prompt health advisories and beach closures. \u201cIt becomes harmful when they are doing something that impacts the health of humans or our pets,\u201d said Kylie Wirebach, an aquatic resource systems analyst with the Pennsylvania Department of Conservation and Natural Resources\u2019 Bureau of State Parks.<\/p>\n

The challenge is how quickly blooms can appear, disappear or shift. Cyanobacteria can move vertically through the water column, gather in pockets and concentrate in places that look clear from the surface. \u201cTrying to find a pattern to anticipate what it\u2019s going to look like for the week, or for the month or for the year is almost impossible,\u201d Wirebach said. \u201cThere are still so many different aspects of harmful algal blooms that are very surprising and hard to predict.\u201d<\/p>\n

How blooms behave at Blue Marsh<\/p>\n

At Blue Marsh, that unpredictability plays out across the lake\u2019s coves, arms and deeper main pool. \u201cIt\u2019s a little bit different every single year,\u201d Treichler said. \u201cThey could be in one area one day and move out to a completely different area the next.\u201d<\/p>\n

Up in the northern arms, the water slows and curls around the shoreline, creating pockets where blooms settle. \u201cThe natural current itself will push the algae and congregate it into the curves we have within the lake itself,\u201d she said. \u201cSo it\u2019s more prone to having blooms in those areas.\u201d<\/p>\n

Farther south, the lake behaves differently. Wind and boat traffic break up the algae and push it deeper. \u201cIn the main pool \u2026 it just distributes throughout the water column,\u201d she said. \u201cEven though you may not see the matting on the surface \u2026 there still can be high concentrations.\u201d<\/p>\n

\"Floating<\/p>\n

Floating buoys create a safety perimeter around the swim beach, where staff conduct routine HAB sampling at ankle, knee and hip depth. (AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

\"A<\/p>\n

A patch of stagnant water shows surface scum and submerged vegetation. Rangers say blooms can shift quickly, sometimes worsening within days after appearing to clear. (AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

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Floating buoys create a safety perimeter around the swim beach, where staff conduct routine HAB sampling at ankle, knee and hip depth. (AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

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\nA system built on caution<\/p>\n

Blue Marsh\u2019s monitoring program is built around consistency and caution, a system that the Army Corps of Engineers began developing in the past several years as it partnered more closely with the Pennsylvania Department of Environmental Protection.<\/p>\n

Staff run weekly in\u2011house toxin tests at the swim beach, while monthly reservoir samples go to DEP for full species identification and toxin analysis. \u201cAny detections that we have had this summer so far have been well within safe standards,\u201d Treichler said.<\/p>\n

If toxin levels ever exceed state thresholds, the response is immediate. \u201cWe would start with closing down the beach,\u201d she said. Staff update social media and the website, issue a press release and post signs throughout the park.<\/p>\n

Wirebach said DCNR follows Department of Health and DEP thresholds for the four cyanotoxins most commonly detected in Pennsylvania lakes: 8 micrograms per liter for microcystin and saxitoxin, and 15 micrograms per liter for cylindrospermopsin and anatoxin\u2011a.<\/p>\n

\u201cWe do lakewide advisories because we can\u2019t predict where the blooms are going to be,\u201d Treichler said.<\/p>\n

\"An<\/p>\n

An algae risk notice stands in front of the Blue Marsh Lake welcome display. (AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

\"Large<\/p>\n

Large bulletin boards at day\u2011use areas carry HAB advisories meant to reach visitors before they enter the water.(AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

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An algae risk notice stands in front of the Blue Marsh Lake welcome display. (AISHWARYA BEHL\/STAFF PHOTO)\n<\/p>\n

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\nSeasonal shifts and longer bloom seasons<\/p>\n

Seasonal patterns are shifting in ways that may influence when blooms begin and how long they last. \u201cIn years where we\u2019ve had a milder winter, we seem to see the harmful algal blooms starting sooner, around May,\u201d said Wirebach. \u201cIf we have a colder winter, it really does take a long time for those blooms to ramp up.\u201d<\/p>\n

At Blue Marsh, staff see the same trend. \u201cJune is when we\u2019ve had some of the earliest advisory statuses,\u201d Treichler said. \u201cThat\u2019s when the lake starts really, as we say, cooking.\u201d<\/p>\n

Last year\u2019s bloom season was unusually intense. It caused a weeklong closure of the main beach and lingered long past summer, persisting into November.<\/p>\n

More than half of the surrounding land is agricultural or urban, which sends nutrient\u2011rich runoff into the reservoir during summer storms. Summer also brings the longest days of the year, higher UV levels and warm water. \u201cAll of the growing conditions become perfect for them in the summertime,\u201d Treichler said. It is also when the lake is busiest, as visitors head to the water to escape the heat. Those overlapping pressures make summer both the peak recreation season and the peak bloom season, a pattern seen across the country.<\/p>\n

Staying safe around the water<\/p>\n

Health effects from cyanobacteria vary widely. Pets and children face the highest risk because they\u2019re more likely to swallow the water. Ingesting cyanobacteria is the main way people and animals are exposed, and pets often drink directly from the lake. Severe cases are rare, but high levels of certain cyanotoxins can cause neurological symptoms.<\/p>\n

Treichler\u2019s guidance to visitors is simple: \u201cWhen in doubt, stay out.\u201d<\/p>\n

Managing an unpredictable system<\/p>\n

Agencies across Pennsylvania are exploring ways to reduce bloom severity, but most long\u2011term solutions depend on watershed conditions that are difficult to control. Both state and federal staff say monitoring and communication remain the most reliable tools for keeping visitors safe.<\/p>\n

Wirebach\u2019s priority is making sure people understand what is happening on the water. \u201cI want people to feel informed,\u201d she said, \u201cand know that a lot of people care to inform them and care to keep them safe.\u201d<\/p>\n

The lake will keep shifting with the weather, the watershed and the seasons. What won\u2019t change, staff says, is the effort to stay vigilant and keep visitors prepared for whatever the water brings.<\/p>\n","protected":false},"excerpt":{"rendered":"The main beach at Blue Marsh Lake Recreation Area in Berks County shimmered under the sun, the water…\n","protected":false},"author":2,"featured_media":257686,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[1131,139,28,128,130,129,231],"class_list":["post-257685","post","type-post","status-publish","format-standard","has-post-thumbnail","category-reading","tag-environment","tag-news","tag-pennsylvania","tag-reading-city","tag-reading-city-headlines","tag-reading-city-news","tag-schuylkill-county"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/posts\/257685","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/comments?post=257685"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/posts\/257685\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/media\/257686"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/media?parent=257685"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/categories?post=257685"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-pa\/wp-json\/wp\/v2\/tags?post=257685"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}