It’s easy to see why people might look at a wastewater treatment plant and assume it’s the primary "factory" for a midge outbreak, but the relationship is a bit more nuanced than a direct cause-and-effect.

The Back River treatment plant handles a massive amount of material—processing about 450 wet tons of dewatered sludge daily— but the recent midge "infestation" isn't necessarily caused by the sludge itself.

The plant uses that "golden egg" for the anaerobic digestion process to stabilize waste. By the time the sludge leaves the plant, it has been heated to nearly 100°F and centrifuged into 25% solids to be shipped out of state. This environment is actually too extreme for midges to breed.

The 2025 population explosion is largely due to a "perfect storm" of weather. Heavy rains and winds have pushed so much freshwater into the Back River that the salinity (salt level) dropped to near zero. This created a massive, hospitable freshwater paradise for midge larvae to flourish in the river's floor.

To manage these swarms, the facility and surrounding areas are treated with Bacillus thuringiensis israelensis (Bti), a naturally occurring, spore-forming bacterium found in soil. This biological larvicide works by targeting the midges at specific times in their life cycle.

What You Can Do

Since the midges are drawn to light and moisture, you can manage them at home without heavy chemicals:

Lighting: Switch to LED or yellow bulbs and move bright lights away from your doors to lure them into unoccupied areas.

Cleaning: Don't bother with "zappers" (they don't work well for midges). Instead, use a marine-safe soap and a hose to ground them.