Deep Water Aeration Restores Municipal Drinking Water Reservoir

Municipal drinking water reservoirs run into the same cluster of problems again and again: low dissolved oxygen, manganese leaching out of the sediment, and high color in the raw water. Any one of them can push treatment costs up and put compliance at risk. Waldron, Arkansas hit all three, and the way the city solved it is a clean example of what deep water aeration can do.

In 2014, Waldron's drinking water reservoir was running high on manganese and color, and the plant was straining to keep up. Conditions had gotten bad enough that the system risked state intervention and a possible takeover of the municipal plant. The city installed deep water aeration around the drinking water intake, and the results showed up fast.

The reservoir

Waldron's reservoir is small. It stores roughly 684 million gallons, the city uses about 528 million gallons a year, and it is fed by a watershed of about seven square miles. Because it is small, water quality can shift quickly during seasonal turnover or a stretch of low oxygen. When oxygen near the bottom drops, manganese and other metals come off the sediment and bring dark water, heavier filtration, higher chemical costs, and compliance risk.

The challenge: manganese and color

Before aeration, raw manganese ran frequently between 1.0 and 3.5 ppm. For context, manganese starts causing staining, metallic taste, and discoloration at levels as low as 0.05 mg/L, so that is a long way over the line. At those concentrations, chemical demand and filtration challenges climb sharply.

The fix: aeration at the intake

The city installed deep water aeration around the drinking water intake and switched it on September 15, 2014. Rather than trying to mix the whole lake, the system targeted the intake zone, circulating oxygen-rich water into the deep areas, preventing oxygen depletion at the bottom, and stopping the sediment from releasing manganese right where the water is drawn for treatment.

The results

The raw water improved quickly once the system was running. The numbers tell the story.

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

Lower manganese and color meant less oxidation and filtration at the plant, cleaner water entering the filters, and steadier operations through the year.

What it meant for the city

The operational payoff was real. Treatment got more efficient, compliance got more reliable, and, most importantly, the improvements headed off the state takeover that had been on the table. By fixing the reservoir instead of only treating its symptoms, Waldron kept control of its own water plant and avoided costly infrastructure it would otherwise have needed.

Deep water aeration works because it treats the root cause, low oxygen at the lake bottom, instead of chasing manganese and color after they are already in the water.

Questions utilities ask

How effective was it at Waldron?

Manganese dropped by up to 90 to 95 percent and raw water color by more than half after the system was installed in September 2014.

How does aeration reduce manganese?

Manganese comes off the sediment when oxygen runs low. Restoring dissolved oxygen near the bottom keeps it bound in the sediment instead of dissolving into the water, so raw water manganese stays lower and easier to treat.

Why do reservoirs develop manganese problems at all?

Seasonal stratification. The deep water gets cut off from the air, its oxygen falls, and manganese and iron dissolve out of the sediment. Aeration restores the oxygen and prevents the release.

Want results like Waldron's for your reservoir? Explore our deep water aeration systems.