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Your Drinking Water Is Under Threat—Long Before It Reaches the Tap

Harmful algal blooms (HABs) are no longer just a summer nuisance — they’re a major threat to water quality, public health, and utility operations. Fueled by nutrient pollution, heat, and stagnant conditions, these blooms can choke your source water, clog treatment systems, and release toxins with devastating health impacts.

The good news? With the right strategy, they’re largely preventable.


What Causes Harmful Algal Blooms?

Algae are always present in surface water — but when conditions align, they can grow out of control. The biggest triggers?

 Nutrient Overload (Eutrophication)

Runoff from farms, lawns, and wastewater adds excess nitrogen and phosphorus, fueling explosive algal growth.

 Warm Temperatures

Climate change and shallow, sunlit reservoirs create ideal bloom conditions.

 Low Water Circulation

Stagnant water creates stratification — a perfect breeding ground for cyanobacteria.

 High Sunlight Penetration

Shallow, unshaded areas allow algae to photosynthesize rapidly, especially in late summer.


Why Algal Blooms Are a Big Deal for Drinking Water Systems

 Toxin Production

Some cyanobacteria release cyanotoxins — harmful to humans, pets, and wildlife even in small doses.

 Taste & Odor Problems

Even non-toxic blooms create musty, earthy smells that degrade water aesthetics and customer confidence.

 Treatment Disruption

Blooms clog filters, increase chlorine and coagulant demand, and elevate the risk of disinfection byproducts (DBPs).

 Ecological Damage

As algae decompose, they deplete oxygen — triggering fish kills and further destabilizing the ecosystem.


How to Prevent Algal Blooms in Drinking Water Reservoirs

1. Cut Nutrient Inputs at the Source

🔹 Agriculture

  • Use buffer strips and cover crops

  • Reduce fertilizer application rates

  • Promote precision nutrient management

🔹 Stormwater

  • Install retention basins, swales, and green infrastructure

  • Filter runoff before it reaches the reservoir

🔹 Wastewater

  • Upgrade treatment plants for enhanced nutrient removal (ENR)

  • Prevent leaks and septic seepage near source water


2. Monitor and Mix

 Monitoring

  • Track chlorophyll-a, cyanotoxins, temperature, and nutrients regularly

  • Use predictive modeling and satellite imaging for early detection

 Circulation

  • Deploy aeration systems or mechanical mixers

  • Break stratification to reduce surface scum and stagnation

 Sunlight Management

  • Use floating covers, shade balls, or natural barriers to reduce photosynthesis in high-risk zones


3. Direct Algae Control (Use with Caution)

 Algaecides

  • Chemicals like copper sulfate kill blooms quickly, but may cause toxin release and regulatory complications

 Biological Controls

  • Introduce filter-feeding fish or use phosphorus-binding agents to reduce bloom potential naturally

 Tech-Based Tools

  • Ultrasonic algae control is showing promise in disrupting cell walls without chemicals


Final Take: Prevention Beats Crisis Management

When it comes to HABs, the real solution isn’t a chemical — it’s a system-wide strategy. Water utilities, municipalities, and private operators need to:

  • Invest in upstream nutrient control

  • Modernize monitoring

  • Treat reservoirs as living systems — not just water sources


How BCG Water Helps Utilities Prevent Algal Blooms

We support:

  • Reservoir vulnerability assessments

  • Watershed-based nutrient reduction plans

  • Treatment plant optimization for algal load response

  • Cyanotoxin testing protocol development

  • Grant writing for green infrastructure implementation

Our goal? Help clients build resilient, bloom-resistant drinking water systems that stay safe, compliant, and trusted.


Call to Action (CTA)

Concerned about algae in your reservoir or surface water intake?
👉 Book a Source Water Risk Review and let’s keep your water clean before it ever reaches your plant.

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