Stressed: Tree loss harms wa­ter

The Glengarry News - - Front Page -

De­for­esta­tion is hav­ing an im­pact on drink­ing wa­ter in the area, where qual­ity ranges from “ex­cel­lent” to “very poor,” and shrink­ing for­est cover has con­trib­uted to “stressed” con­di­tions in the South Na­tion River water­shed.

Ar­eas where sur­face wa­ter qual­ity is poor typ­i­cally have low for­est cover along the banks of rivers, lead­ing to a loss of fil­tra­tion, ero­sion con­trol and habi­tat, the South Na­tion Con­ser­va­tion Author­ity notes in its State of the Na­tion Water­shed Re­port Card.

Ground­wa­ter, which is found in un­der­ground aquifers, is an im­por­tant and vi­tal nat­u­ral re­source, since it pro­vides drink­ing wa­ter to more than 95 per cent of the ru­ral pop­u­la­tion within the SNC’s ju­ris­dic­tion.

“We rely on na­ture for mul­ti­ple ben­e­fits for both a healthy, pro­duc­tive en­vi­ron­ment and healthy peo­ple,” says Kather­ine Wat­son, SNC’s Wa­ter Re­sources Spe­cial­ist.

The elim­i­na­tion of trees along wa­ter cour­ses has led to in­creased sed­i­men­ta­tion.

En­vi­ron­ment and Cli­mate Change Canada rec­om­mends that 75 per cent of stream length be nat­u­rally veg­e­tated on both sides (i.e. the ri­par­ian area). In the water­shed, the ri­par­ian cover is poor. “At only 22 per cent, our pro­grams and projects need to take a re­newed fo­cus on in­creas­ing ri­par­ian cover,” cau­tioned Ms. Wat­son.

To­tal for­est cover in the SNC ju­ris­dic­tion is “good,” es­ti­mated at 28 per cent in 2014, with for­est cover be­ing the low­est in the cen­tral re­gion of the basin.

En­vi­ron­ment and Cli­mate Change Canada rec­om­mends a minimum 30 per cent for­est cover to help re­duce flood­ing and ero­sion, fil­ter air and wa­ter, pro­vide wildlife habi­tat, and sup­port aquatic sys­tems at a water­shed scale.

While the fed­eral agency rec­om­mends ten per cent, for­est cover is 8 per cent in the for­est in­te­rior, the wooded area that is more than 100 me­tres from a for­est’s edge, the habi­tat that is re­quired by many species for sur­vival.

How­ever, the water­shed en­joys a strong wet­land cover rating at 17 per cent, pro­vid­ing nat­u­ral flood man­age­ment dur­ing peak flows and wa­ter re­ten­tion reser­voirs dur­ing dry weather. “Wet­lands also fil­ter pol­lu­tants and pro­vide im­por­tant wildlife habi­tat,” Ms. Wat­son noted.

En­vi­ron­ment and Cli­mate Change Canada rec­om­mends 10 per cent wet­land cover.

Wet­lands pro­vide nat­u­ral flood con­trol dur­ing peak flows and act as wa­ter reser­voirs dur­ing dry weather. They fil­ter pol­lu­tants be­fore they enter streams, pro­vide im­por­tant habi­tat for plants and an­i­mals, and pro­vide numer­ous eco­nomic, recre­ation, and aes­thetic ben­e­fits.

Wet­lands in­clude swamps, marshes, fens, and bog habi­tat.

En­com­pass­ing 4,384 square kilo­me­tres, the SNC ju­ris­dic­tion com­prises parts of Stor­mon­tDun­das-Glen­garry, Prescot­tRus­sell, Ot­tawa, Leeds and Grenville. From head­wa­ters north of Brockville, the South Na­tion River flows north­east for 175 kilo­me­tres, and emp­ties into the Ot­tawa River near Plan­ta­genet.

Visit na­­ter/re­ports/water­shed-re­port-cards to see the full re­port card.

All over the map

Wa­ter qual­ity in the South Na­tion ju­ris­dic­tion cov­ers the gamut for a num­ber of rea­sons.

Phos­pho­rus lev­els rou­tinely ex­ceed the Pro­vin­cial Wa­ter Qual­ity Ob­jec­tive (0.03 mg/L), while ben­thic in­ver­te­brate com­mu­ni­ties range from unim­paired to poor (im­paired) con­di­tion, de­pend­ing on the lo­ca­tion.

Ben­thic macroin­ver­te­brates are small crea­tures, such as in­sects, mol­lusks and worms, that live in the river. They are very sen­si­tive to pol­lu­tion and are ex­cel­lent in­di­ca­tors for wa­ter qual­ity and stream health.

Phos­pho­rus is nat­u­rally oc­cur­ring in rivers, but can be el­e­vated due to de­ter­gents, fer­til­iz­ers, and sewage. Too much can re­sult in al­gae blooms, af­fect­ing oxy­gen lev­els, and the fish and biota that live there.

Chlo­ride and ni­trate con­cen­tra­tions are bet­ter than drink­ing wa­ter stan­dards in most wells. Sev­eral wells have higher chlo­ride con­cen­tra­tions, which are nat­u­rally oc­cur­ring due to the in­flu­ence of the Cham­plain Sea.

Chlo­ride is a nat­u­rally oc­cur­ring el­e­ment, how­ever, con­cen­tra­tions can be in­creased in shal­low ground­wa­ter sys­tems due to hu­man ac­tiv­ity, such as road salt, land­fills, and sep­tic sys­tems, and in deeper wells it oc­curs nat­u­rally from de­posits of the pre­vi­ous Cham­plain Sea from post-glacial melt­ing and flood­ing.

Ni­trate can nat­u­rally oc­cur in rocks and ground­wa­ter, how­ever, con­cen­tra­tions can be in­creased by hu­man ac­tiv­i­ties such as leaky sep­tic sys­tems and ap­pli­ca­tion of ex­ces­sive amounts of fer­til­izer.

Although wet­land cover in the ju­ris­dic­tion is meet­ing minimum guide­lines, wet­lands have been greatly re­duced over the last 200 years. Pre-set­tle­ment (c.1800) wet­land cover es­ti­mates for the ju­ris­dic­tion are at 40 to 50 per cent, largely the re­sult of the last Ice Age.

The Cham­plain Sea was a tem­po­rary in­let of the At­lantic Ocean cre­ated by re­treat­ing glaciers dur­ing the close of the last Ice Age. The best ev­i­dence of this for­mer sea is the vast clay plain de­posited along the Ot­tawa and St. Lawrence Rivers. This re­sulted in dis­tinc­tive for­est types, large wet­lands, and as­so­ci­ated ecosys­tems.

The qual­ity of for­est cover con­di­tions were mea­sured us­ing Geo­graphic In­for­ma­tion Sys­tems (GIS) and ae­rial im­agery from 2014.

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