The Pleasant Lake Protective Association regularly partners with leading limnologists, environmental scientists, and regional lake stewards to share vital research with our community.
Explore featured slide decks and recorded video lectures below to learn how regional climate patterns, watershed runoff, and lake dynamics affect Pleasant Lake — and what proactive steps every resident can take.
Climate Change and Our Lakes: What It Means for New Hampshire
Presented at the 2026 NH Lakes Congress by Dr. Craig Williamson, Ph.D.
Craig Williamson, Ph.D., Limnologist
Emeritus Professor, Miami University (Oxford, OH) • Watershed Committee Chair, Pleasant Lake Protective Association
69 Slides • PDF (3.4 MB) • June 2026
How to Access Slide Speaker Notes
In the PDF presentation, comprehensive speaker notes and annotations are embedded in the slides. You can access these notes by opening the PDF in Adobe Acrobat (or another full-featured PDF reader) and clicking on the small folder/note icon in the upper-left corner of each slide.
Key Topics & Takeaways
Warming & Extreme Weather
New Hampshire lakes are warming faster than global air or ocean averages. Pleasant Lake has experienced an average surface water temperature increase of ~2°F over the past 25 years, while winter ice cover duration has decreased by nearly a full month.
Storm Runoff & Lake Browning
Severe storm events flush dissolved organic matter (DOM) and nutrients from the watershed into the lake. This causes "browning," which shades deep waters, depletes deepwater dissolved oxygen, and triggers internal sediment phosphorus release.
Cyanobacteria & Tipping Points
While long-term trends show low average nutrients, short-term signals in 2024 and 2025 demonstrate sudden vulnerability to cyanobacteria blooms when warm waters, reduced sunlight UV disinfection, and nutrient flushes converge.
Essential Stewardship Actions
Practical measures to protect Pleasant Lake: eliminate lawn fertilizers, preserve deep-rooted native shoreline buffers, pump and inspect septic tanks every ~3 years, avoid wake-boat sediment churning, and eliminate dock de-icers.
Watch: CyanoHAB Talk
A presentation by Doug Darling on cyanobacteria dynamics, risks, and proactive lake monitoring.
Doug Darling, a resident of a nearby lake who has studied cyanobacteria extensively, gives a detailed overview of Harmful Algal Blooms (CyanoHABs). This talk explains how cyanobacteria form, what conditions spur rapid growth, and why vigilant observation and quick reporting are essential for swimmer and pet safety.
Have You Spotted a Suspected Bloom?
Report surface scums or discolored water promptly to help protect our community and pets.
Related Lake Protection Resources
Explore complementary research reports, monitoring data, and watershed stewardship guidelines.
VLAP & Lake Monitoring
Read annual NH DES VLAP water testing reports, deepwater temperature and oxygen profiles, and tributary studies.
Bloom Safety & Identification
Learn how to recognize cyanobacteria scum, avoid exposure, protect dogs, and report bloom sightings directly.
Watershed Management
Understand how runoff from roads, driveways, and lawns feeds nutrients into the lake and how buffer plantings help.