Deep Water Aeration Restores Municipal Drinking Water Reservoir

How Waldron, Arkansas Reduced Manganese by 90% and Stabilized Drinking Water Quality

Municipal drinking water reservoirs frequently struggle with low dissolved oxygen levels, manganese release from sediments, and high color levels in raw water. These issues can dramatically increase treatment costs and threaten regulatory compliance.

In 2014, the city of Waldron faced a serious water quality challenge in its drinking water reservoir. The municipal lake that supplies the city’s drinking water was experiencing elevated manganese concentrations and high color levels, creating treatment challenges at the water plant.

Conditions had deteriorated to the point where the system risked state intervention and potential takeover of the municipal water treatment plant.

To solve the issue, the city installed deep water aeration systems around the lake’s drinking water intake. The results were immediate and dramatic.

Background: Waldron’s Drinking Water Reservoir

The municipal reservoir supplying Waldron is relatively small, serving the community’s drinking water needs with limited storage capacity.

The reservoir:

• Stores approximately 684 million gallons of water

• Has an average annual water use of roughly 528 million gallons

• Is supplied by a watershed of about 7 square miles

Because of the reservoir’s small size, water quality changes can occur rapidly during seasonal turnover or periods of low oxygen.

When oxygen levels drop near the lake bottom, manganese and other metals can be released from sediments, leading to:

• Dark or discolored drinking water

• Increased filtration requirements

• Higher chemical treatment costs

• Regulatory compliance risks

The Challenge: Rising Manganese and Color Levels

Prior to aeration installation, water testing showed elevated raw manganese levels and high color units in the reservoir water.

These parameters created operational challenges at the water treatment plant.

Raw Manganese (ppm)

Before aeration installation, manganese levels were frequently observed between:

1.0 – 3.5 ppm

For context, manganese in drinking water typically becomes problematic at concentrations as low as 0.05 mg/L, where it can cause dark staining, metallic taste, and discoloration. 

High manganese levels dramatically increase chemical demand and filtration challenges during drinking water treatment.

The Solution: Deep Water Aeration Around the Intake

To address the problem, deep water aeration systems were installed around the drinking water intake.

The system was activated on September 15, 2014.

Deep water aeration works by:

• Circulating oxygen-rich water into deep areas of the reservoir

• Preventing oxygen depletion at the lake bottom

• Stopping manganese release from sediments

• Improving overall water column stability

Rather than mixing the entire lake, the system targeted the intake zone, improving water quality directly where water is withdrawn for treatment.

Water Quality Results After Aeration Installation

The improvement in raw water quality occurred rapidly after aeration began operating.

Raw Manganese Reduction

Before aeration:

• Typical levels: 1.0 – 3.5 ppm

After aeration:

• Stabilized near 0.2 – 0.4 ppm

Improvement

Approximately 80–90% reduction in manganese concentration

This dramatically improved the treatability of the water at the plant.

Settled Manganese Reduction

Even more dramatic improvements were observed in settled water samples.

Before aeration:

• Typical settled manganese: 1.5 – 2.7 ppm

After aeration:

• Levels dropped to 0.05 – 0.15 ppm

Improvement

Up to 95% reduction in settled manganese levels

These reductions significantly reduced the burden on filtration systems.

Raw Water Color Improvements

Color units also showed a measurable improvement after aeration was installed.

Before aeration:

• Raw color levels ranged between 250 – 340 color units

After aeration:

• Stabilized near 110 – 150 color units

Improvement

Approximately 50–60% reduction in raw water color

Lower color levels directly translate into reduced chemical usage and easier clarification during treatment.

Stabilization of Settled Color

Settled water color values also improved significantly.

Before aeration:

• Values frequently exceeded 10–14 color units

After aeration:

• Most readings fell between 1–6 color units

This represents a significant improvement in water clarity entering filtration systems.

Operational Impact for the Water Treatment Plant

The improved raw water quality provided several major operational benefits.

Improved Treatment Efficiency

Lower manganese and color levels reduced the amount of chemical oxidation and filtration required.

Reduced Risk of Regulatory Non-Compliance

By stabilizing raw water quality, the city was able to maintain reliable drinking water production.

Avoided State Intervention

Most importantly, the improvements in water quality prevented the potential state takeover of the municipal water plant that had been under consideration due to treatment challenges.

Key Results

Water Quality Improvements

Parameter	Before Aeration	After Aeration	Improvement
Raw Manganese	1.0–3.5 ppm	0.2–0.4 ppm	~80–90% reduction
Settled Manganese	1.5–2.7 ppm	0.05–0.15 ppm	Up to 95% reduction
Raw Color	250–340 CU	110–150 CU	~50–60% reduction
Settled Color	10–14 CU	1–6 CU	Major stabilization

Why Deep Water Aeration Works for Drinking Water Reservoirs

Deep water aeration is an effective method for improving reservoir water quality because it addresses the root cause of manganese and color problems: low oxygen conditions at the lake bottom.

When bottom waters lose oxygen, manganese and iron dissolve from sediments and enter the water column.

Aeration systems restore oxygen levels, preventing these metals from entering the raw water supply.

Benefits include:

• Lower manganese and iron concentrations

• Reduced taste and odor issues

• Improved water clarity

• Lower treatment chemical usage

• More stable drinking water quality

A Proven Solution for Municipal Water Utilities

The results observed in Waldron demonstrate how deep water aeration can dramatically improve drinking water reservoir performance.

By targeting the intake zone with aeration technology, the city was able to:

• Improve water quality

• Reduce treatment challenges

• Protect regulatory compliance

• Avoid costly infrastructure upgrades

For municipalities relying on lakes or reservoirs as drinking water sources, aeration can provide a cost-effective solution to manganese, color, and oxygen depletion issues.

Learn More About Deep Water Aeration

Advanced Treatment Technologies provides deep water aeration systems designed to improve drinking water reservoirs, municipal lakes, and raw water supplies.

Our systems help municipalities:

• Reduce manganese and iron

• Improve dissolved oxygen levels

• Stabilize raw water quality

• Lower treatment costs

Learn more about our technology here:

https://www.advancedtreatmenttechnologies.com/deepwateraeration

Deep Water Aeration FAQ

What is deep water aeration?

Deep water aeration is a process used in lakes and drinking water reservoirs to inject oxygen into deeper water layers. By maintaining dissolved oxygen near the sediment layer, aeration prevents manganese and iron from dissolving into the water column and improves overall water quality for municipal treatment plants.

How does aeration reduce manganese in drinking water reservoirs?

Manganese is released from lake sediments when oxygen levels become depleted. Deep water aeration restores dissolved oxygen near the lake bottom, preventing manganese from dissolving into the water. This keeps raw water manganese levels significantly lower and easier to treat.

How effective is deep water aeration?

In the City of Waldron, Arkansas reservoir, deep water aeration reduced manganese levels by up to 90–95% and reduced raw water color by more than 50% after installation in September 2014.

Why do drinking water reservoirs develop manganese problems?

Many drinking water reservoirs experience seasonal stratification where deep water becomes oxygen depleted. When this occurs, manganese and iron dissolve from lake sediments into the water column. Aeration systems restore oxygen levels and prevent this release.