Natural Hazards in Squamish 1 District of Squamish Where the Rivers Meet the Sea Lessons from the Past HIGHWAY 99 Official Community Plan Adopted 2010 SQUAMISH RIVER The District of Squamish is located at the head of Howe Several conclusions can be drawn from the flood history in VER Schedule D1 YE RI CHEEKE Sound where 5 rivers converge. These mountain rivers, Squamish: FLOOD AND DEBRIS FLOW fed by glaciers, snowmelt and precipitation, descend HAZARD AREAS from their steep mountain tops carrying water, sediment, 1. All the rivers in Squamish pose a risk of flooding. All have Levette Legend Lake and on occasion, rocks and other debris. When these fast Evans Cr B Debris Flow Hazard Area r Brohm Lake o h caused multiple and damaging floods in the past. m Riv Flood Hazard Area !!! e r Dykes flowing rivers reach the gently sloping valley, they tend to Parks and Ecological Reserves Paradise Valley Rd 2. Damaging floods have also occurred as a result of coastal Indian Reserves Boundaries slow down and spread out, and leave sediment behind. Evans hazard zones Lake The terms alluvial fan and floodplain are used to describe inundation. Source: Cheekye River Terrain Hazard and Land Use Study, March 1993 HAZARD ZONES 1. Alluvial fan hazard zone - level 1 (high) the riparian areas along these lower river reaches. 4 2. Alluvial fan hazard zone - level 2 (intermediate) 3. The flood risk in Squamish has strong seasonal variations. Most C 6 H 3 Cat E 3 3. Alluvial fan hazard zone - level 3 (moderate) ER E Lake s Cr IV K Evan R E 5 Y 4. Alluvial fan hazard zone - level 4 (low) S 2 E 1 U R flooding has taken place between October and December. Major I AM V 5. Cheakamus & Squamish River Flood Plain E 1 R ECK H 3 1A 6. Cheakamus River displacement flood area C 5 li c Stump e L Lake d a 1 R k 2 y e floods have also taken place in August. e all R ish V d Brackendale Squam NOTE: Creeks west of the Squamish River are subject 4 1 Alice Lake Eagles Provincial Park to debris flows although the boundaries of the affected Provincial 2 99 3 2 areas have not been mapped. Park AY W Alice H Lake G Skwxwú7mesh Úxwumixw Oral History - 4. Contrary to other B.C. communities, the freshet (typically in late 3 Rd HI ss Ro Baynes Island Govern 3 Ecological ! 4 m r Reserve ! 4 en C May, June and early July) has not been a major cause of flooding t R r ! en The Flood d d C y r ! h Depot R d D c n a ! p R on local rivers. ! Ho ! Judd Rd ! ! ! ! The oral history of the Skwxwú7mesh Úxwumixw ! ! ! ! ! ! ! M a ! ! s h ! i ! t er C (Squamish Nation) has a legend called the Flood. 5. The frequency of flood damages over the past 30 years has F ! r r Brackendale ! ie s C Eagles ! r Provincial ! e Park Eagle g ! d i decreased compared to earlier time periods. This is attributed to Viewsite R r According to the legend, when the people began to d D r i h ! t b r r e M Pe am d n quam ! u h T Rd Gar Mam iba The Boulevard quam ld R ! i d W investments in structural flood protection (i.e. dikes). a y forget their old ways and failed to listen to their elders, y ! a W d s d t R an hl ! en Hig m S n er Mamquam Rd ! v ! o G ! ! ! ! ! ! ! ! ! ! ! ! the game began to disappear and then the fish and the ! ! ! ! ! ! ! ! !! !! ! 6. Extreme precipitation (rain and snow) has occurred on at least ! ! ! ! ! ! ! ! ! ! Railway !!!!!! ! ! Museum berries. People became hungry and began to quarrel. Still ! Leisure Centre 5 occasions since 1980. These continue to test the limits of flood ! Queens Way ! MAMQU Industrial AM RIVER they wouldn’t listen to their elders and change their ways. ! Way Finch Dr ne protection structures. ! s La Monmouth Cr r ge o ! r og d BC Hydro L Then the rains came. The waters rose and the people had Hy ! C B ! B u c k l e ! y A v e ! to anchor their canoes to Nch’kay’ (Mt. Garibaldi). When Ave ! ay stw ! We In addition to the 5 major rivers and their tributaries, the District’s ! Pemberton Av e R ! ! ! r ! ! D R ! rd E ! fo ! V ! ild I ! u R ! ! ! e G the waters receded, the people who survived came to ! v S ! A ! ! e l U nd n e ! M la La land area also includes numerous small, steep creeks that can n ! A ve s ! e r l n W ! ! ! C ge A a T h Log S C ! d their senses and listened to their elders. Then the game n ! li B present flood, debris flow, sedimentation, and erosion hazards. SQUAMISHRIVE ! m a u q ! m Stawamus Chief a and the fish and the berries returned in abundance. M Provincial Park Stawamus Chief Provincial Park Mi r ll C en C es r Ol Oct 1984 Darrell Cheekeye River Bay S ha The recorded history of the Squamish community HOWE SOUND nn on C Dec 1980 r Aug 1958 Cheakamus River Shannon Falls Squamish River shows a constant struggle to protect human Provincial Cheekeye River Stawamus River Park Gonzal Cheakamus River Major debris flow Dec 1967 Log bridge across settlement from the natural forces that have e s Howe Sound Mamquam River Cr Oct 1950 following a sudden the Cheakamus River 9 frequently led to flooding. Over the past century, Y 9 Oct 1955 Sea dike was Stawamus River A W Squamish River rainstorm H destroyed and damaged G I H Mamquam River overtopped & Logjams on 3 rivers Squamish has experienced numerous floods as Murrin Browning Prov. Lake Damage to roads homes Park led to damages to 200 and rail bridges Mamquam Bridge Downtown Squamish outlined below. washed out for flooded. homes and closure of District of Squamish Bylaw No. 2100, 2009 10th time in 28 Highway 99 years 1890s 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s 2000s 2010s Aug 1991 Oct 2003 1890s Oct 1921 Dec 1932 Dec 1951 Cheakamus River Oct 1940 Oct 1958 Oct 1981 Squamish River Squamish River Mamquam River Howe Sound Howe Sound Largest flood in 50 years Squamish River Squamish River Nov 1968 Squamish River Cheakamus River First River Dike proposed Sept 1906 Squamish River Overtopping of Sea dike was breached (369 mm in 4 days) caused Evacuations from Four feet of water Mamquam River 177 mm of rain in Cheekeye River Squamish River Flood covered valley the sea dike in in two places District evacuations and Brackendale to over the main road in Flooding damaged a 48 hours 15 houses on Cheakamus I.R. “Many settlers were floor Downtown damaged the BC rail line Downtown Brackendale trailer park, highways No. 11 were flooded and the completely wiped out” Dikes were not overtopped (Myrtle Herndl) and the railway access road to Paradise Valley was washed out .