Tracking turbidity Impact of watershed logging on water quality debated HEN THE Greater Vancouver Regional District’s water management division (GVWD) selected chlorine as a secondary disinfectant for the Lower Mainland’s drink- ing water on June 29, some environmentalists, such as North Vancouver District Coun. Janice Harris, let out half a cheer. By Greg Felton Contributing Writer On the one hand there was praise for the GVWD’s rejection of its own earlier recommendation of chloramine. Anti-chloramine groups and individuals lobbied hard against the original recommenda- tion because of the known danger _ chloramine poses to fish and aquat- ic habitats. In the end, the GVWD rejected it pretty much on this score alone, said Doug Neden, GVWD manager of water treatment ard research. Harris, even though she would prefer ozonated water treatment, told the News the choice of chlo- rine over chloramine represented “a long and arduous victory for the public and the environment.” But groups like the Western Canada Wilderness Committee (WCWC) were less char- itable. Paul George, chairman of the WCWC, told the News that the $1-billion rechlorination and disinfection system wouldn't be needed if logging were not permitted in the watershed. “We want the GVRD (Greater Vencouver Regional District) to let the tree roots cure the siltation problem," he said. Siltation of our drinking water is one of the major reasons behind the GVWD’s Brinking Water Quality Improvement Plan (DWQIP) begun in 1988. The standard against which the GVWD mea- sures the quality of cur water is the Canadian Drinking Water quality guidelines, The revised standards stipulate a much lower acceptable level of disinfection byproducts, such as tri- halomethanes. The old standard was 350 micro- grams (pg) /L; the new one és 50 tig/L. “We go by what the drinking standards indi- cate,” said Neden. ‘We strive to nivet levels they set, like for disinfection byproducts. Both chto- tine and:ozone with filtration will meet that guideline. The only reason (we tested ozone) is that it's perceived by people to be better; there isn’t.a technical reason to go with it.” ng. conta the chlorine de: wently fails national SF tarbiity guide- lines, ceeding to'a Decezaber 1993 Greater Vancouver: regions 7 District water mana diviston {GVWD) tect nd of t ‘why the lan) ddlentifi nephelometric turbidity. igita articles such ‘as allt, - a beam of Ugh when itis f suspended pa b 8 ‘dleintoctian ‘Is not omproniived: 2. tothe:GVWD: c In 1986 the concentration of chlorine in our water was 0.2 mg/L. Today, it is 1.5 mg/L. said GVWD silvicuituralist Brian De Gusseme. Environmentalists point the finger al logging and raud constriction in the three watersheds. These activities, they say, cause soil instability which leads to erosion and landslides. “When they did the carthqueke upgrade work (on ihe Cleveland Dam), [ think it was two years ago, they found that the reservoir had 10% less capacity because it’s been filling up with silt. 1 see the roads and the clearcnts as a highly proba- bie suspect.” said independent rescarcher Greg Helten, Last year, Helten produced a half-hour video called Greater Vancouver's Water: Gur Future which set out the environmentalist opposition to watershed logging. One of those interviewed, professional forester Herb Hammond, said the best filter and purifier of our water is the old- growth forests. “The old-growth forest system acts like a giant sponge to hold water and slowly release it: the older the forest; the better the sponge,” said Hammond, “If your goal is to provide high-quality water timed well throughout the year then you should stay out of the forests and let it provide water, : ath rimary: disinfectants and Inter ering with . thelr. detection; Material:asseclated with the particle can increase. water, ‘preventing the establishment of ~ ctamit:residual-in the distribution system. For ” urbidity isa: heulth-related concern, not simply an... wet i i pworr (Drinking: GVED' Quality. . nerandum, : water t im: Cépliano ; time; Seymour Lake 5%} and - ‘quitties debate the. ‘merits of chio- 4 GVRD.: There's no way human beings can improve that function — all they can do is degrade it.” On the other side of the argu- ment, De Gusseme said the cloudi- ness of our water is due to natural conditions, not the GVWD's man- agement of the watershed. “There has been a long history, 80 years or so, of turbidity prob- lems in the Capilano watershed and a lot of it is duc to the parent mate- tials of this drainage system.” He said one reason that the Coquitlam watershed has such a superior quality of water is that its banks are in bedrock or in sand, whereas Capilano’s foundations are largely fine glacial clay which stays suspended in water. In addition, he said low reser- voir levels during maintenance periods contribute to sediment buildup because a lot of banks slough into Capilano Lake when there isn’t the water pressure to keep them in, The Capilano watershed’s geol- ogy, together wilh soil exposed from blown-dow: trees and winter storms — which cause flooding and landslides — are the causes of our frequent poor water quality. It is a general position of the GVRD that a hands-off approach to the watershed would only add to the erosion problem. The greatest threat to our water according to GVYRD management is erosion and turbidity satised by catastrophic fire, The GVRD‘s watershed management pro- gram is designed to mitigate this damage by thinuing out the forests, planting hardier species, and selectively harvesting areas where blow- downs are likely to oecur, As for a hands-off approach, Dr. Tom Griffing, project manager for the GVRD's watershed ecological inventory dismisses it as "a gross oversimplification” of a very complex problem. The 199¢ Final Watershed Management Evaluation and Policy Review is a contentious document that the GVRD and its critics each use to buttress their respective arguments. This is the first instalment of a series of arti- cles in which News contributing writer Greg Felton investigates some of the key issues involved in the ongoing debate about the quaiity of our drinking water supply, In subsequent instalments, the News will examine both sides of the issue: to log or not to log and what effect loguing has on our water, Next Sunday: the GVRD's Forest Management Strategy. 6) NTU = Neohelometric Turbidity Unit CAPILANO 5- 30 NTU 214 days (14. 5%) et Pee 3A >30 NTU 5 days (0.3%) —