News
When your local reflecting pool or pond turns green with algae, don’t reach for chemicals – nature has better solutions
When ponds and reflecting pools turn green with algae, chemical “quick fixes” often fail. Here’s how nature-based solutions like Daphnia and aquatic plants can restore water quality longer-term.
Eric Palkovacs, University of California, Santa Cruz
When the Lincoln Memorial Reflecting Pool turned green with algae just days after a US$15 million renovation, the U.S. government scrambled for chemicals and expensive technical solutions to fix the iconic landmark.
Trying to kill algae with chemicals is a common response when community ponds or other water features go green. But as a scientist who studies freshwater ecology, I can tell you there are better solutions that cost far less, last longer and carry less risk of harm to pets and wildlife.
Rather than battling against nature, these alternatives work with nature for long-term solutions. https://www.youtube.com/embed/nkqBQ1r0Kto?wmode=transparent&start=0 If you need to treat a slimy, green, algae-filled body of water, you shouldn’t drain and refill the water, which resets the entire ecosystem. Instead, one solution is quite simple and relies on nature, not chemicals.
What went wrong on the National Mall
The algal bloom that turned the Reflecting Pool a vibrant green shouldn’t have been a surprise.
The pool is big, more than a third of a mile long and around 165 feet wide. But it’s shallow, meaning it warms up quickly in the sun. When it was repainted “American flag blue” during the renovations in spring 2026, the new color darkened the pool, and darker colors absorb more heat.
On top of those conditions, the pool was refilled with water from the nutrient-rich tidal basin of the Potomac River. The combination of warm water and nutrients created prime conditions for algae to bloom, turning the water pea soup green.
As the national conversation over the Reflecting Pool shifts to political finger-pointing, an important environmental question deserves careful scrutiny: What is the best approach to maintain water quality in a case like this, whether for a national monument or a community water feature or pond?
Trying to chemically or mechanically remove algae can damage the structure of a water feature and may harm species in the water that could actually help solve the problem.
Importantly, chemical and mechanical solutions are only temporary fixes. When the Reflecting Pool is drained and filled again, there’s a good chance that algae will bloom again.
Natural algae control
Limnologists – scientists like me who study inland water bodies – have spent many decades learning why lakes and ponds turn green and how to clear them up.
Often, nutrient-rich waters fueled by fertilizer runoff from farm fields or sewage from cities are the sources that stimulate algal growth.
However, natural ponds also host grazing zooplankton, which eat algae. For example, a type of zooplankton called Daphnia, known as water fleas because of the way these tiny crustaceans swim, can control algae by consuming it before it becomes a pea soup nuisance. Thus, a thriving Daphnia population can help maintain good water quality in a lake, pond or community water feature, even when nutrient levels spike.
In addition to being highly effective grazers, Daphnia have another superpower – they can evolve rapidly. Urban waterbodies are often harsh environments with a variety of challenges, including high temperatures, low levels of dissolved oxygen, and pollutants. Daphnia can adapt to tough conditions, making these creatures an ideal source of algae control in many urban ponds.
Rooted aquatic plants are also useful for algae control in ponds because they absorb nutrients. Thus, shallow ponds with thick beds of aquatic plants can often resist algal blooms when nutrient levels rise.
Why draining might not be the best solution
One downside to draining and refilling a pond or urban water feature to try to clean it is that doing so resets the aquatic ecosystem, erasing the signature of any past evolution that has taken place.
Imagine Daphnia in a shallow pond that experiences periodic heat waves throughout the summer. Through repeated exposure to high temperatures, natural selection favors heat-resistant genotypes that can thrive in an urban pond.
Daphnia and other grazing zooplankton can also evolve resistance to some types of cyanobacteria, also known as blue-green algae, which produce compounds that are toxic to people and pets. Daphnia that evolve resistance to those toxins can help control harmful cyanobacterial blooms.
If a Daphnia population that evolved to tolerate warm temperatures, low oxygen levels or cyanotoxins is removed, the new population likely won’t be ready to handle those local challenges. This evolutionarily naive population will perform poorly in its new environment, reducing its effectiveness at controlling algal blooms.
As a result, traditional mechanical and chemical approaches may actually work against the goal of minimizing algae in ponds and other water features.
Nature-based solutions
The use of Daphnia to control algal blooms is just one example of solving environmental challenges with nature-based solutions.
Growing urban forests to provide cooling and improve air quality to help reduce the need for more energy-intensive air conditioning is another example. Maintaining urban wetlands can help reduce flooding, protect property and recharge groundwater more effectively and for less money than building and maintaining levees. Coastal marshes similarly reduce erosion, buffer storm surges and support fisheries.
All these urban ecosystems protect biodiversity and support human health and well-being.
From national landmarks to city parks and backyard ponds, projects of all sizes can take advantage of nature-based solutions. While each specific project is unique, some general principles apply.
Ecosystems are most resilient when they are diverse and connected. So, it is beneficial to use a variety of species and genotypes and provide corridors that support the movement of organisms and their beneficial genes.
Urban climates are changing rapidly, so it helps to use species and genotypes that will thrive under future conditions, including rising temperatures.
Not every solution has to be engineered
The hubbub over the Reflecting Pool holds a mirror up to assumptions about how to solve pressing environmental challenges. The idea of just engineering one’s way out of any environmental crisis has limits.
Understanding ecology and nature’s mechanisms of ecosystem resilience can achieve sustainable solutions that benefit both nature and people.
Eric Palkovacs, Professor of Ecology and Evolutionary Biology, University of California, Santa Cruz
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Last Updated on November 13, 2026 by Daily News Staff
STM Daily News | November 12, 2026
Graffiti Cleanup Transforms Oceanwide Plaza
LOS ANGELES — The unfinished skyscrapers known as downtown Los Angeles’ “Graffiti Towers” have reached a visible milestone: most of the exterior tagging has been removed, although completing the long-stalled Oceanwide Plaza development remains a separate challenge.
City officials celebrated the cleanup November 12. According to the mayor’s office, crews cleared graffiti from roughly 250 balconies across the three-tower complex opposite Crypto.com Arena and near the Los Angeles Convention Center. Remaining work has included touch-ups on windows and other exterior areas.
Oceanwide Plaza was envisioned as a mixed-use destination with residences, a luxury hotel, shops and restaurants. Construction stopped in 2019 after Beijing-based developer Oceanwide Holdings could no longer finance the project.
In early 2024, trespassers covered the unfinished towers with graffiti, turning them into an internationally recognized sight. The property also attracted dangerous stunts and heightened concerns about security.
The development entered bankruptcy in February 2024. This July, a bankruptcy court approved a purchase arrangement involving KPC Square, a joint venture between KPC Group and Lendlease. Graffiti removal began while the acquisition was still pending.
What Comes Next for LA’s Graffiti Towers?
The partnership is targeting a January 2027 closing, according to the Los Angeles Business Journal. Financing, a construction contract and required approvals remain important steps before the development can be completed.
For downtown residents and businesses, the cleanup marks tangible progress at a prominent property. However, it does not mean the towers are ready to open, and no firm opening date has been announced.
Sources
- Los Angeles Mayor’s Office, November 12, 2026: https://mayor.lacity.gov/news/mayor-bass-celebrates-graffiti-removal-oceanwide-plaza-clearing-way-full-restoration-and
- Los Angeles Business Journal, November 9, 2026: https://labusinessjournal.com/real-estate/cleaning-up-oceanwide/
- City News Service / MyNewsLA, November 12, 2026: https://mynewsla.com/life/2026/11/12/graffiti-cleanup-milestone-marked-at-oceanwide-plaza-in-downtown-la/
Forgotten Genius Fridays
David Crosthwait: The Engineer Behind Indoor Comfort
David Crosthwait helped solve the challenges of heating large buildings, including Radio City Music Hall. Explore his inventions and lasting engineering legacy.
Forgotten Genius | STM Daily News
When audiences enter New York’s Radio City Music Hall, they notice the stage, the lights, and the sweeping auditorium. The engineering that keeps the building comfortable rarely receives applause.
One of the people behind that comfort was David Nelson Crosthwait Jr., a Black engineer and inventor whose work helped advance heating, ventilation, and temperature control in large buildings.
His career offers a reminder that some of the most useful inventions work quietly around us.
Solving the Problem of Heating Large Buildings
Heating a large building takes more than producing enough heat. Different areas can have different needs: one side may face bitter wind while another receives warming sunlight. Delivering the right amount of heat throughout the building requires careful control.
Crosthwait devoted much of his career to those challenges. A Purdue University engineering graduate, he worked for the C.A. Dunham Company, developing equipment and systems for heating and ventilation.
His inventions included improvements to boilers, thermostat controls, and vacuum pumps. These components helped engineers manage the movement and regulation of heat in larger buildings.
One example appears in U.S. Patent No. 1,727,965, granted in 1929. The patent describes a vacuum steam-heating system designed to serve different sections of a building at different steam pressures. That allowed the system to address varying heating needs while using a shared steam source.
Behind the technical drawing was a practical question: How could one building provide comfortable conditions in spaces that needed different amounts of heat?
His Connection to Radio City Music Hall
Crosthwait’s best-known projects included designing the steam-heating system for Radio City Music Hall at Rockefeller Center.
It was a fitting assignment for an engineer whose expertise centered on the demands of large buildings. While performers entertained audiences, the systems behind the scenes helped make the experience comfortable.
His contributions extended across a substantial body of work. The National Inventors Hall of Fame credits him with 39 U.S. patents and 80 international patents, spanning heating, refrigeration, controls, and other technologies.
Sharing Knowledge and Breaking Barriers
Crosthwait also helped other engineers learn. He wrote technical material, contributed to engineering guides, and later taught steam-heating theory and control systems at Purdue.
In 1971, he became the first Black Fellow of the American Society of Heating, Refrigerating and Air-Conditioning Engineers. Purdue awarded him an honorary doctorate in 1975, and the National Inventors Hall of Fame inducted him in 2014.
His legacy rests in the practical details of engineering: controlling pressure, improving equipment, and making complicated systems work together.
The next time you settle into a comfortable auditorium on a cold evening, consider the ingenuity behind that warmth. David Crosthwait helped make indoor comfort an engineering achievement worth remembering.
Discover more inventors and innovators through the Forgotten Genius series in The Knowledge at STM Daily News.
Related Links
- National Inventors Hall of Fame: David Crosthwait — Biography covering his inventions, patent totals, Radio City Music Hall work, teaching, and professional honors.
- Rockefeller Center: A Rock Center Innovator — Highlights his role in designing Radio City Music Hall’s steam-heating system.
- Original 1929 Patent: U.S. Patent No. 1,727,965 — Technical drawings and Crosthwait’s description of a steam-heating system serving different building sections at different pressures.
- Purdue University Libraries: Historical Timeline — Documents his 1913 graduation and contributions to heating, ventilation, and air conditioning.
Sources: National Inventors Hall of Fame, Rockefeller Center, Purdue University Libraries, and U.S. Patent No. 1,727,965.
Family
The House That Hosts: When Your Home Becomes Your Holiday Entertaining Partner
The House That Hosts: There’s a special pleasure in opening your home for the holidays to share the menu you’ve imagined, welcome guests to the glow of a room ready for company and enjoy the anticipation of familiar faces at the door. This year, make sure the house itself can lend a hand.
The House That Hosts: When Your Home Becomes Your Holiday Entertaining Partner
(Feature Impact) There’s a special pleasure in opening your home for the holidays to share the menu you’ve imagined, welcome guests to the glow of a room ready for company and enjoy the anticipation of familiar faces at the door. Every detail is an opportunity to make the loved ones you’ve invited feel especially welcome.
This year, make sure the house itself can lend a hand.
From the kitchen to the living room to the guest bathroom, residential technology offers new ways to turn a host’s imagination into a memorable experience. The best innovations don’t take over the occasion. They help the person bringing everyone together make it extraordinary.
Nor does a home need an elaborate network of connected gadgets. A few well-chosen technologies can make a difference. Explore these ideas from the bathroom design and technology experts at TOTO to level up the different hosting areas of your home as you prepare to gather with family and friends this holiday season.
The Kitchen: Bringing Something Extraordinary to the Table
The holidays invite a little culinary ambition, and today’s kitchens are borrowing a few tricks from professional chefs.
Imagine presenting a beef tenderloin cooked to a perfect rosy pink from edge to edge, thanks to the precision of sous vide cooking. Or bringing a platter of roasted root vegetables to the table, their edges beautifully caramelized and their centers tender, prepared in a steam-convection oven. On an induction cooktop, precise, responsive heat helps turn fresh mushrooms into a golden, savory accompaniment.
These technologies put sophisticated techniques within reach of adventurous home cooks, opening the door to new preparations and dishes worthy of special occasions. Experiment with new flavors and rich cuisines that fill your home with enticing aromas and your guests with awe at the first bite.
Nothing says “happy holidays” quite like watching guests discover what you’ve created for them.
The Living Area: Setting the Stage for Connection
Holiday gatherings have a rhythm all their own. The first arrivals are greeted with excitement, conversations pick up where they left off months (or years) prior, and before long, the room is filled with laughter and the pleasure of being together.
Today’s smart lighting systems allow hosts to create and schedule scenes that shift from the sparkle of a festive welcome to the softer, golden glow of an intimate evening. Multiroom wireless audio systems can bring lively music into the kitchen while keeping it a gentle accompaniment to conversation in the living area. Digital art displays can turn a television screen into a gallery of artwork chosen to complement the celebration, bringing holidays past to life as loved ones mingle in the present.
Successful holiday entertainment engages people not merely as observers, but participants. A short film could start an inspiring conversation, the right music might get people dancing and atmospheric visual-audio experiences, like a crackling fireplace or soft snowstorm, can create a relaxing seasonal backdrop for shared activities.
With the atmosphere changing quietly in the background, no one needs to interrupt a favorite story to adjust the lights or lower the music. The host can simply enjoy the company they’ve brought together.
The Bathroom: The Art of Personal Comfort
The most gracious hosts think beyond the rooms where guests gather. Fresh towels, fragrant soaps and a few unexpected comforts can make the guest bathroom feel every bit as welcoming as the rest of the home.
Technology adds a new dimension to that hospitality. Consider a TOTO WASHLET bidet seat, which offers the welcome warmth of a heated seat, the refreshing pleasure of warm-water cleansing and the soothing comfort of warm-air drying. It’s an unexpected luxury that makes an everyday experience feel special.
Hosts can choose an option that complements their home’s character. The S2 offers inviting simplicity with convenient side-panel controls. The sleek S5 pairs contemporary elegance with a wireless remote. Meanwhile, the S7A adds a touch of theater with a lid that opens automatically, a softly glowing nightlight and personalized cleansing settings.
Even the housekeeping benefits from a little ingenuity through automatic PREMIST and EWATER+: One mists the toilet bowl before use to help keep it cleaner, while the other cleans the cleansing wand and, on select models, the bowl itself with electrolyzed water.
It’s another way a thoughtful host can anticipate guests’ needs and make them feel wonderfully welcome.
Long after the last guest has departed, what lingers isn’t the sophistication of the house. It’s the meal that inspired compliments, the conversations no one wanted to end and the little surprises that made everyone feel at home.
Those are the moments that make holiday entertaining special. Behind each one is a host whose warmth, creativity and attention to detail made it possible, with a little help from the house. Explore more sophisticated bathroom upgrade ideas for the holidays and beyond at TOTOUSA.com.
Photo courtesy of Shutterstock (holiday table)
SOURCE:
TOTO
