2026 Current Conditions

Our weekly monitoring and updates are officially underway for the 2026 season!

Weekly Water Quality Update 9/2/2026

Lake Winnisquam Heads Toward Fall Turnover

Lake Winnisquam is beginning its transition toward fall turnover, with surface water temperatures continuing to cool. The thermocline has deepened to approximately 31 feet this week. Water clarity declined this week, potentially due to stormwater runoff from recent rainfall, along with continued low-density cyanobacteria growth. Water levels remain slightly higher than the mean for this time of year but have not fluctuated greatly.

WWN will continue monitoring water quality throughout September as Lake Winnisquam moves toward fall turnover. We'll continue to share updates and keep you informed about changing lake conditions.

Continuous Monitoring Provides a Closer Look

WWN's continuous monitoring buoys are measuring lake conditions closely and providing valuable data between our regular sampling events. Over the past week, the buoys have not detected any unusual spikes in phycocyanin or chlorophyll-a. Both pigments have remained relatively stable, with daily peaks that coincide with the daily migration patterns of algae and cyanobacteria through the water column.

This continuous monitoring is an exciting addition to our water quality program. Earlier this summer, our buoys detected spikes in phycocyanin that coincided with our observations of increased Gloeotrichia throughout the lake. As those observations decreased, the phycocyanin levels also leveled out. Seeing the continuous buoy data correspond with what we are observing in the lake is encouraging and gives us another useful tool for tracking changing conditions.

We’re excited to see that the data from our continuous monitoring buoys are so far lining up with what we are observing in the lake. This gives us another valuable tool for tracking changes in cyanobacteria conditions and understanding what is happening between our regular sampling events allowing WWN to respond more quickly to changing conditions while providing valuable long-term data to support lake management. Learn more about our buoys here.

Stay Alert

Cyanobacteria conditions can change quickly, and conditions may vary from one area of the lake to another. Please take a moment to look at the water before entering, even if conditions appeared clear earlier in the day. Only you can decide what level of risk you are comfortable with, but when in doubt, stay out.

WWN and NHDES will continue monitoring Lake Winnisquam and will provide additional updates if conditions change.

If you observe suspected cyanobacteria bloom or unusual surface accumulation, please submit a report through the NHDES Bloom Report Form and notify the Winnisquam Watershed Network. You can also contribute observations through WWN's Plankton Patrol project on CitSci. These reports help our staff and volunteers verify conditions and provide timely information to the community.

Get Involved

If you are interested in becoming involved with water quality monitoring or other volunteer stewardship opportunities, we encourage you to contact WWN. Community volunteers play a vital role in helping preserve and protect Lake Winnisquam and its watershed for future generations.

While these weekly updates often focus on scientific observations, they also remind us why protecting Lake Winnisquam matters. A healthy lake provides countless benefits to our community, from swimming, boating, paddling, and fishing to supporting wildlife, providing clean water, and offering a place to relax, reconnect, and create lasting memories with family and friends.

The continued health of Lake Winnisquam is the result of many people working together. Every lake-friendly action, whether it's cleaning, draining, and drying your boat, reducing runoff from your property, minimizing wake near shorelines, or respecting wildlife, helps preserve this incredible resource for future generations.

As we head into the end of the summer season, we encourage you to take a moment to appreciate everything it provides. Together, we can ensure that Lake Winnisquam remains a healthy, vibrant, and welcoming place for generations to come.

Helpful links for current conditions:
For real-time lake level information, visit NHDES' Real-Time Data and Information page
For current advisories, watches, and warnings visit NHDES' Healthy Swimming Mapper.

Stay informed, stay safe, and check your inbox for your weekly water quality updates. Follow us on social media to stay updated on what’s happening around the lake.