We brought a poisoned wetland back to life

Acid water does not stop at the fence

Water off old coal workings carries acid and metals into the Olifants river system, and that water feeds Loskop Dam and the farms below it. A healthy wetland filters this naturally. Zaalklapspruit sat in the right place to do that work, and could not. Decades of erosion had cut channels straight through it. The water passed through untouched.

Fix the wetland, then prove the fix

With Working for Wetlands we rebuilt the plumbing, forcing water to spread and slow instead of cutting through. Then came the harder part. Eight years of measurement to show the recovery was real. Groundwater and isotope work traced where the wetland draws its water in the dry season. When engineered erosion barriers proved too expensive, the team tested Dongalock, interlocking shutters cut from recycled PVC, against them, and the cheap local product held its own.

One gap remained. There was no accepted way to score how badly acid water has damaged a wetland, or how far it has recovered. So the team built one, a diatom index, the first of its kind for South African wetlands. Diatoms are microscopic algae that respond fast to water chemistry. Count the right species and the wetland tells you how it is doing.

The site the industry points to

When someone says rehabilitation is a fiction, this is the counterargument with grass on it. A wetland that measurably cleans mine water again, at a fraction of what a treatment plant costs to run forever. The monitoring methods built here now guide wetland offset planning across the coalfields, where 36,500 hectares of offset rehabilitation have been identified. The diatom index gives mines and the regulator one shared measure of recovery. And the water keeps getting cleaner whether anyone is watching or not.