Introduction
Across drinking water reservoirs and managed lakes, operators keep coming back to the same question: what is the best practice to prevent algae growth while still protecting ecosystems, budgets and public trust? Blooms can seem to appear almost overnight, turning clear water into green streaks or scums, releasing toxins, and in the worst cases forcing closure of raw-water intakes or popular recreation areas.
Algae are a normal part of freshwater food webs, but excess nutrients and a warming climate are tipping many lakes toward more frequent and intense blooms. Scientific agencies such as NOAA and the U.S. Geological Survey (USGS) have documented how harmful algal blooms (HABs) can trigger fish kills, create taste and odour issues, and lead to economic losses for communities that rely on reservoirs for drinking water, irrigation and recreation.
In the following sections, we unpack why algae grow excessively, which preventive measures matter most, and how an integrated monitoring and control strategy can change day-to-day operations. We also show how LG Sonic’s Monitoring-Buoy and MPC-Buoy work together so utilities can anticipate blooms instead of reacting only after they show up at the surface.
Why algae growth is a challenge in lakes and reservoirs?
Uncontrolled algae growth affects far more than just the look of a lake. Dense blooms cut down water clarity, shade out aquatic plants and change oxygen levels throughout the water column. When algae die off and start to decompose, bacteria consume large amounts of oxygen, which can stress or even kill fish and other aquatic organisms.
Certain cyanobacteria (blue‑green algae) also produce toxins, such as microcystins, that can affect the liver or nervous system of humans, pets and livestock. The World Health Organization (WHO) and the U.S. Environmental Protection Agency (EPA) both highlight that managing cyanobacterial blooms in lakes and reservoirs is essential for protecting drinking‑water safety and recreational use.
For water utilities, blooms often show up as higher treatment costs, shorter filter runtimes and more customer complaints about earthy or musty tastes. Understanding the local drivers of algae growth in a particular reservoir is the first step toward choosing the best practice to prevent algae growth there.
What drives algae growth in freshwater reservoirs?
Most harmful algal blooms in lakes and reservoirs depend on three main ingredients: plenty of nutrients, enough light and relatively stable water conditions. Excess nitrogen and phosphorus from agriculture, treated wastewater or urban runoff can build up in the basin. Warm, still surface layers with long residence times then create ideal conditions for buoyant cyanobacteria to out‑compete other phytoplankton.
Studies by USGS and EPA show that nutrient enrichment, together with warmer water, tends to increase bloom frequency in many freshwater systems. In stratified reservoirs, a warm surface layer sits on top of cooler bottom water and limits vertical mixing. Buoyant cyanobacteria can stay close to the surface, where both light and nutrients are easiest to access.
Long‑term nutrient reduction in the catchment is therefore a central part of the best practice to prevent algae growth. Optimising fertiliser use, restoring wetlands and improving stormwater management can gradually lower the nutrient load feeding blooms, although changes in the reservoir itself may take several years to become clearly visible.
Monitoring: The foundation of prevention
Because lakes and reservoirs change from day to day, effective prevention starts with watching those changes closely. A modern water quality monitoring system typically combines in‑situ sensors, data loggers and telemetry to track chlorophyll‑a, phycocyanin, temperature, turbidity, dissolved oxygen and pH in real time.
When data arrive every few minutes instead of once a week, operators can start to see early‑warning patterns: rising algae indicators, a surface layer that is warming faster than usual, or turbidity peaks right after heavy storms. Agencies like NOAA and USGS increasingly combine satellite imagery with in‑situ measurements to map bloom hotspots and understand how they evolve across larger water bodies.
In our previous article on water quality monitoring systems, we described how buoy‑based platforms can collect data from the middle of a lake rather than only at the shore. LG Sonic’s Monitoring‑Buoy follows this same idea by measuring key parameters throughout the year and sending them to cloud software, where dashboards and alerts support everyday operational decisions.
Alton Water reservoir lake, Suffolk, England, UK landscape scenery near Tattingstone
What is the best practice to prevent algae growth in lakes and reservoirs?
In practice there is no single tool that can solve every algae problem. The best practice to prevent algae growth is to combine several layers of defence: catchment management, continuous monitoring and targeted control inside the water body itself. Together, these elements help managers anticipate blooms, respond earlier and check whether any intervention is really working.
This kind of integrated strategy means reducing nutrients where possible, tracking key parameters in real time and using selective, data‑driven control tools in lakes and reservoirs. Within that framework, LG Sonic’s Monitoring‑Buoy and MPC‑Buoy play complementary roles in putting the best practice to prevent algae growth into daily operations.
Monitoring-Buoy: Preventing algae with early warning
A buoy‑based monitoring platform often sits at the heart of the best practice to prevent algae growth because it shows when physical and chemical conditions are drifting toward bloom‑friendly ranges. The Monitoring‑Buoy collects chlorophyll‑a, phycocyanin, temperature, turbidity, dissolved oxygen and pH data at regular intervals and sends them to user‑friendly web dashboards.
With this kind of information, reservoir managers can see, for example, when surface waters are warming earlier than usual, when algal pigment levels begin to climb, or when oxygen near the bottom quietly declines. They can adjust intake depths, tweak operating rules or plan other site‑specific actions before a potential bloom disrupts treatment or recreation.
The Monitoring‑Buoy is designed specifically for lakes and reservoirs, offering continuous measurements without the need for permanent structures along the shoreline. For more details, visit LG Sonic’s Monitoring‑Buoy product page.
MPC-Buoy: Reducing existing algae growth
When algae are already abundant, prevention alone is no longer enough to stabilise the system. The MPC‑Buoy combines the same real‑time monitoring capabilities with low‑power, targeted ultrasound to disrupt algae where they grow. By adjusting ultrasonic programmes to local water conditions, the system reduces algal biomass and helps restore clearer, more stable conditions in larger freshwater bodies.
In drinking water reservoirs, this kind of control can translate into fewer taste and odour episodes, more stable turbidity at the plant intake and longer filter runtimes. Independent case studies, such as the City of Archie in Missouri, report substantial turbidity reductions and roughly a 300% increase in filter runtime after installing MPC‑Buoy, which helped the utility rebuild public confidence in its treated water.
Used together with continuous monitoring, the MPC‑Buoy closes the loop between observing conditions, predicting blooms and actively controlling algae growth without adding new substances to the water. This approach fits well with the best practice to prevent algae growth in drinking water reservoirs and other sensitive freshwater uses.
For a broader overview of what the system can do, consult the MPC‑Buoy product page, which explains how monitoring, prediction and ultrasound control are combined in a single platform.
Conclusion: Turning data into preventive action
In summary, the best practice to prevent algae growth in lakes and reservoirs is to treat prevention and control as one continuous process rather than two separate steps. Nutrient management in the catchment reduces long‑term pressure, continuous monitoring with systems like the Monitoring‑Buoy provides early warning, and adaptive control with MPC‑Buoy reduces existing blooms and helps stabilise water quality.
By following this integrated approach, reservoir managers can minimise the risk of harmful algal blooms, protect drinking‑water treatment plants and safeguard aquatic ecosystems. Instead of reacting to green water at the shoreline, they gain the insight and tools needed to keep algae in check before problems reach the communities that rely on these freshwater resources every day.