Dashboard # Provincial Lead Contact: Media Relations contact: Provincial Flood Status Update Manager, River Forecast Centre & Flood Safety Provincial Information Coordination Officer Date: July 16, 2020, 3:30 pm Freshet 14 George Roman Thomas Winterhoff Manager, River Forecast Centre and Flood Safety Senior Public Affairs Officer [email protected] [email protected] 250-896-2725 778-974-4380 Provincial Summary No severe or widespread flooding is expected this week – however, rainfall in parts of the Central Rockies and Mountains continue to cause elevated rivers, streams, and lakes across these regions. A Flood Watch remains in place for the Quesnel River watershed and was issued this morning for tributaries of the Upper Fraser watershed due to potential for some localized issues. Apart from these specific locations, most water bodies in the province are dropping this week and have very low flood risks. Provincial staff, local government staff, First Nations, and other parties continue to monitor the situation and support implementation of flood emergency response as necessary. Weather (Current and Forecast) The Central Interior is experiencing rainy weather today, especially in mountainous areas of the Upper Fraser and Cariboo, where 10 - 40mm of rain has already fallen in the last 24 hours or so, and moderate rain continues to fall. Another low-pressure system moving towards Fort Nelson has started to spread rain across the far northeast. Fortunately, dryer conditions are expected this weekend across most of the province. Next week, the recent trend of unsettled cooler and unsettled summer weather will persist across the central and north, while dry, sunny summer weather will dominate most of the southernmost portions of the province.

Flood Warnings and Advisories Hydrometrics and Forecasting Flood Watches are in place today for the Quesnel River After reaching a 50-year flow on July 5-6, the Quesnel River remains and Upper , including tributaries such as the high and susceptible to today’s rainfall. Although river responses to date Dore River, McGregor River, and McKale River. have been small, the Quesnel River could continue to increase over the next few days and may approach peaks seen earlier in the season. High Streamflow Advisories are in place for the Fraser River mainstem from Marguerite to Boston Bar, and the Tributaries of the Upper Fraser River, Robson Valley, and north Cariboo Middle Fraser tributaries including areas around Williams region are also increasing, including the Dore River, McGregor River, Lake and Boston Bar. and McKale Rivers. However, floods are not expected to be as severe in these locations. There are no Flood Warnings in place for today. The Lower Fraser River at Hope is currently flowing at 8,100 cubic The Current Flood Warnings and Advisories public map metres per second (cms), and continues to recede from the high flows must be consulted for up to date information, watches, observed over the last few weeks. It is not anticipated that the rainfall and warnings. in the Upper Fraser will cause significant rises in the Lower Fraser River, although a bump in flows back to around 8,500 cms next week is likely.

Map of Forecast Flows within the Next 5 days (July 16th, 2020) Flood Warning and Advisory Map (July 16th, 2020) The River Forecast Centre public website is updated daily and should be consulted for up to date information.

*All model outputs are subject to uncertainty, change, and revision. In addition, the level of service of federal and provincial partner agencies at remote snow and river gauges is affected to some extent by operating constraints due to COVID-19, which may further reduce forecast accuracy.

Active Floods of Note Snow Conditions Areas affected by high water today include the Quesnel River, , and . The risk of snowmelt freshet contributing to seasonal extreme floods has subsided significantly. Remaining extreme flood risks extending through the summer depend much more on heavy summer rainfall events. Resources The majority of provincial snowpack has melted. Some very high elevation (>2000 m) mountain snowpack still remains, with amounts highly Emergency Management BC (EMBC) continues to support communities and First Nations throughout the province variable based on region, aspect, and elevation. The provincial Snow Conditions webpage includes more detailed information. The final with seasonal readiness, preparedness, and response, including coordination of flood-related resources and asset snow bulletin of the year was released on June 19th. deployments where they are needed most. FLNRORD staff throughout the province continue to support these efforts through their roles and responsibilities as outlined in the Provincial Flood Emergency Plan.

Definitions: Flood Warnings and Advisories High Streamflow Advisory River levels are rising or expected to rise rapidly, but no major flooding is expected. Minor flooding in low-lying areas is possible.

Flood Watch River levels are rising and will approach or may exceed bankfull. Flooding of areas adjacent to affected rivers may occur.

Flood Warning River levels have exceeded bankfull or will exceed bankfull imminently. Flooding of areas adjacent to the rivers affected will result.

Hydrometrics and Forecasting Hydrometric Conditions Current water flow and/or level conditions, based on the federal Water Survey of Canada (WSC) hydrometric gauge station sites indicating flood conditions in BC, based on a total of 247 WSC stations, binned by flood frequency analysis.

Forecast Return Period Forecast (estimated) future water flow and/or level conditions, based on the BC River Forecast Centre’s hydrologic models. The primary spring freshet flood forecasting model is the Channel Links Evolution Efficient Routing (CLEVER) model. For spring 2020, the CLEVER model includes outputs for 266 sites.

The return period values represent the inverse measure of the probability of a particular flow occurring in any given year. For example, a 50-year flow has a probability of 1/50 or a 2% chance of occurring in any given year, a 100-year flow has a 1/100=1% chance of occurring in any given year, a 20-year flow has a 1/20 or 5% chance of occurring in any given year, a 5-year flow has a 1/5=20% chance each year, etc. Flood Frequency Analysis Statistical analysis of historic peak flows used to understand the frequency or probability of extreme flows.

Snow Basin Index Estimated average snow water equivalent (e.g. amount of water contained in the snowpack) across a watershed basin relative to its historic average.