Lake Champlain Water Quality Hits a Ten-Year High

City beaches had 94 swimmable days this summer, the most in a decade, according to the parks department. That number, released this week in the department’s end-of-season water report, marks a sharp improvement from the summers of the mid-2010s, when beach closures from algae blooms and high bacteria counts were so common that some families stopped planning lake trips altogether.

The report covers the city’s four public beaches, which are tested by parks staff several times a week from Memorial Day through Labor Day. A beach is counted as swimmable when bacteria levels are within state guidelines and no harmful algae bloom has been spotted. This year, the main city beach was closed only four days all summer, and two of those closures came after the same heavy thunderstorm in July.

What the numbers show

Parks officials said the 94-day total was not a single lucky summer but the high point of a steady trend. Over the last ten years, the number of swimmable days at city beaches has risen in most seasons, with a few dips during especially hot or rainy summers.

Highlights from this year’s report include:

• 94 swimmable days at city beaches, the most since the department began publishing season totals in its current format.
• Fewer algae bloom alerts than any summer in the last decade, with most short-lived and confined to shallow coves.
• Lower average bacteria readings after storms, which the department credits to improvements in how rainwater is handled across the city.
• Clearer water at the main beach, measured by how deep a white testing disk stays visible from the surface.

“For years, people asked us whether the lake was getting better or worse,” said parks director Linda Haskell. “This summer, we can finally give a clear answer. It’s getting better.”

Why it improved

Farm runoff programs and new stormwater gardens are reducing pollution. Scientists and city officials say there is no single fix behind the cleaner water. Instead, they point to dozens of projects, large and small, that have slowly cut the amount of phosphorus and other pollutants reaching the lake.

Phosphorus is the main ingredient that feeds algae. It comes from fertilizer, manure, eroding stream banks, and runoff from roofs, streets and parking lots. When heavy rain washes it into the lake, it can fuel thick blooms of blue-green algae, especially in warm, shallow water.

Clean water doesn’t happen by accident. It’s years of small fixes.

Dr. Ellen Brooks, lake scientist

Brooks, who has studied the lake for nearly 20 years with a regional research institute, said the improvement reflects work done far outside city limits as well as within them. “The lake doesn’t care about town lines,” she said. “Every farm and every parking lot in the watershed plays a part.”

On the farms

Across the watershed, many dairy and crop farms have joined voluntary and state-supported programs to keep soil and manure on their fields. Common practices include planting cover crops after harvest so soil isn’t bare all winter, leaving strips of grass and trees along streams, and storing manure so it doesn’t wash away in spring storms.

A farmer who grows corn and hay about 20 miles from the city told Maple & Main that cover crops took a few seasons to get right. “The first year I wasn’t sure it was worth it,” he said. “Now my soil holds water better, and I’m not watching it wash into the creek every April.”

In the city

Inside the city, the biggest change has been in how rainwater is managed. Over the last eight years, the public works department has built more than 60 stormwater gardens — shallow, planted basins along streets and in parks that catch runoff and let it soak into the ground instead of rushing into storm drains.

The city has also upgraded parts of its wastewater treatment plant, separated some combined sewer pipes, and offered rebates to homeowners who install rain barrels or redirect downspouts onto lawns.

What residents can do

City officials stressed that individual households play a role too. The parks department’s report includes a short list of simple steps that help keep the lake clean:

1. Skip lawn fertilizer, or use a phosphorus-free product, especially near streams and the shoreline.
2. Pick up after pets so waste doesn’t wash into storm drains.
3. Point downspouts toward lawns or gardens instead of driveways.
4. Keep leaves and grass clippings out of the street, where they can wash into drains and add nutrients to the water.
5. Wash cars at a commercial car wash, which treats its water, rather than in the driveway.

The city’s rain barrel rebate program, which covers up to $50 of the cost of a barrel, will reopen in the spring.

Still a concern

Scientists warn hot summers can still bring algae blooms. Warm water, calm winds and a heavy rainstorm can still combine to trigger a bloom, even in a good year. Brooks said the lake has a long memory: phosphorus that built up in the sediment over decades can be released into the water during hot stretches.

Some parts of the lake are also doing better than others. Shallow bays to the north, which are surrounded by farmland and warm up quickly in summer, still see blooms most years. The city’s beaches benefit from deeper, cooler water and from the stormwater work done nearby.

“We should celebrate this summer,” Brooks said. “But one great season doesn’t mean the job is done. A few very hot years in a row could undo some of the progress if we stop paying attention.”

The parks department reminds swimmers to check the city’s beach status page before heading out and to avoid water that looks like pea soup, spilled paint or has a scum on the surface. People and pets should stay out of water during a bloom, and anyone who feels sick after swimming should contact a doctor.

Looking ahead

Next year, the city plans to build another dozen stormwater gardens, including several along streets that drain directly to the lake. Public works will also begin a three-year project to replace aging storm pipes under parts of the downtown waterfront.

Regional researchers will also continue their long-running monitoring program, which samples water at more than a dozen spots around the lake every two weeks from spring through fall. Brooks said those records, some stretching back decades, are what allow scientists to tell a real trend from a lucky year. Her team plans to add sensors to two buoys near the city next summer that will measure water temperature and algae levels every 15 minutes and send the readings to shore in real time.

The parks department plans to add a live water quality display at the main beach, showing the latest test results and current conditions. Officials say the goal is to make the information as easy to check as the weather.

Key takeaway: The lake is cleaner than it has been in a decade, thanks to years of steady work by farmers, city crews and residents — but keeping it that way will take the same patience going forward.

For now, many families are simply glad to have their beach back. On the last warm weekend of the season, the main beach was crowded with swimmers, paddleboarders and kids building sand castles at the water’s edge. It looked, one longtime resident said, “the way a summer beach is supposed to look.”