As forests burn world­wide, drink­ing wa­ter is at risk

Antelope Valley Press - - SECOND FRONT - By TAMMY WEB­BER

Fab­ric cur­tains stretch across the huge War­ragamba Dam to trap ash and sed­i­ment ex­pected to wash off wild­fire-scorched slopes and into the reser­voir that holds 80% of un­treated drink­ing wa­ter for the Greater Syd­ney area.

In Aus­tralia’s na­tional cap­i­tal of Can­berra, where a state of emer­gency was de­clared on Fri­day be­cause of an out-of-con­trol for­est fire to its south, au­thor­i­ties are hop­ing a new wa­ter treat­ment plant and other mea­sures will pre­vent a re­peat of wa­ter qual­ity prob­lems and dis­rup­tion that fol­lowed deadly wild­fires 17 years ago.

There have not yet been ma­jor im­pacts on drink­ing wa­ter sys­tems in south­east Aus­tralia from the in­tense fires that have burned more than 40,000 square miles since Septem­ber. But au­thor­i­ties know from ex­pe­ri­ence that the big­gest risks will come with re­peated rains over many months or years while the dam­aged ar­eas re­cover.

And be­cause of the size and in­ten­sity of the fires, the po­ten­tial im­pacts are not clear yet.

The sit­u­a­tion in Aus­tralia il­lus­trates a grow­ing global con­cern: Forests, grass­lands and other ar­eas that sup­ply drink­ing wa­ter to hun­dreds of mil­lions of people are in­creas­ingly vul­ner­a­ble to fire due in large part to hot­ter, drier weather that has ex­tended fire sea­sons, and more people mov­ing into those ar­eas, where they can ac­ci­den­tally set fires.

More than 60% of the wa­ter sup­ply for the world’s 100 largest ci­ties orig­i­nates in fire-prone wa­ter­sheds — and count­less smaller com­mu­ni­ties also rely on sur­face wa­ter in vul­ner­a­ble ar­eas, re­searchers say.

When rain does fall, it can be in­tense, dump­ing a lot of wa­ter in a short pe­riod of time, which can quickly erode de­nuded slopes and wash huge vol­umes of ash, sed­i­ment and debris into cru­cial wa­ter­ways and reser­voirs. Be­sides re­duc­ing the amount of wa­ter avail­able, the runoff also can in­tro­duce pol­lu­tants, as well as nu­tri­ents that cre­ate al­gae blooms.

What’s more, the area that burns each year in many for­est ecosys­tems has in­creased in re­cent decades, and that ex­pan­sion likely will con­tinue through the cen­tury be­cause of a warmer cli­mate, ex­perts say.

AS­SO­CI­ATED PRESS

In this Jan. 7, 2011, file photo, wa­ter flows from a wa­ter foun­tain at the Boys and Girls Club in Con­cord, N.H.

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