There are a lot of misconceptions about aquifers, groundwater and our potable water supply; so to begin I am going to provide a mini-primer on aquifers. As described by Environment Canada:
An aquifer is an underground formation of permeable rock or loose material which can produce useful quantities of water when tapped by a well. Aquifers come in all sizes and their origin and composition is varied. They may be small, only a few hectares in area, or very large, underlying thousands of square kilometres of the earth's surface. They may be only a few metres thick, or they may measure hundreds of metres from top to bottom.
There are two major types of aquifers: confined and unconfined. As described by the US Geological Service:
A confined aquifer is an aquifer below the land surface that is saturated with water. Layers of impermeable material are both above and below the aquifer, causing it to be under pressure so that when the aquifer is penetrated by a well, the water will rise above the top of the aquifer. A water-table, or unconfined, aquifer is an aquifer whose upper water surface (water table) is at atmospheric pressure, and thus is able to rise and fall. Water-table aquifers are usually closer to the Earth's surface than confined aquifers are, and as such are impacted by drought conditions sooner than confined aquifers.
In an unconfined aquifer the
level below which all the spaces are filled with water is called the water table. Above the water table lies the unsaturated zone. Here the spaces in the rock and soil contain both air and water. Water in this zone is called soil moisture. The entire region below the water table is called the saturated zone, and water in this saturated zone is called groundwater (ref).
Note: for those of you who went to school in the 1990s (or before) you would have used the term “vadose zone” rather than the more modern term “unsaturated zone”.
An unconfined aquifer can be refreshed by a number of means. The most obvious is via rainfall. Rain that hits a permeable surface can percolate through the soils of the unsaturated zone eventually ending up as groundwater. If input exceeds output then the water table rises. If drawdown exceeds the input then the aquifer surface (water table) will drop. Unconfined aquifers often also live in harmony with surface water bodies. Streams that run over an unconfined aquifer can refresh the aquifer when it is low and can be sourced by the aquifer when the water table is higher. Similarly, an aquifer can be fed by a bigger water body like a lake. In that case the lake can serve as a reservoir for the aquifer, allowing users to draw groundwater with the aquifer being refreshed by the lake water. Using the terminology the aquifer is hydraulically connected to the lake. As long as the lake is there the aquifer will remain at a relatively steady state.
In the lower mainland the groundwater supply is dominated by unconfined aquifers. In my local community (the Township of Langley) we have a hybrid water system:
The Township is one of the few municipalities in the Lower Mainland that relies heavily on groundwater, for agricultural, commercial, industrial and residential uses; 23% of the Township is not supplied by the municipal drinking water system, and residents in these areas rely on private wells. However, the majority of the Township’s population live in areas served by one of two municipal water systems. The smaller eastern system is entirely groundwater based, while the larger western system supports 61% of the Township’s total population, and is a mix of groundwater (40%) and Greater Vancouver Regional District (GVRD) [now called Metro Vancouver] surface water (60%). The Township prefers to use its own available groundwater, as it is significantly cheaper than purchasing surface water from the GVRD. The Township of Langley operates 18 municipal wells, and private wells number at least 5,000 (ref).
I live in a part of the community supplied with GVRD water which is sourced from reservoirs north of the Fraser River. The Capilano and Seymour Watersheds in the north shore mountains, and Coquitlam Watershed in Coquitlam each feed reservoirs which serve as our water source (ref). These reservoirs are fed by watersheds whose water is sourced by a combination of precipitation and snowfall runoff. Since these reservoirs are finite, once the snow has all melted any water taken from them during the dry season is not returned and the reservoir levels start to drop. After a winter with an unusually low snow pack and a particularly dry spring the water levels in our three local reservoirs are already dropping precipitously which is starting to cause water managers to be concerned. This explains the water restrictions in my part of town.
My father-in-law lives in the community of Aldergrove, in the southeast corner of the Township. His water comes from a groundwater-based system using a number of municipal wells that draw from a number of smaller unconfined aquifers including the Aldergrove and Abbotsford Aquifers (ref). These aquifers (along with the Hopington Aquifer) represent some of our region’s most threatened groundwater resources. The problem is that these aquifers are used by the community of Aldergrove, by residences in the agricultural lands, by agricultural users and are also important sources for a number of very important salmon streams. For those of you unfamiliar with the area, almost 75% of the Township of Langley is in the Agricultural Land Reserve (ALR) and agricultural users, in the ALR, are given priority in water use battles. The increasing and sustained use of these smaller unconfined aquifers is having a negative effect as drawdown in summer has continuously exceeded the inflow in winter. As such a number of these unconfined aquifers are threatened and thus the Township developed a Water Management Plan. As part of that plan the Township is spending a good deal of money to hook Aldergrove up to the Metro Vancouver water supply to reduce the stress on the aquifers, but until then water restrictions are even heavier in that part of the community. Even in non-drought years come summer my father-in-law is not even allowed to wash his car by hand...a true hardship according to him.
So how does this all relate to Nestlé way up in Hope? Well like us the District of Hope is under water Stage IV water restrictions which even limits the hand watering of lawns (ref). As such you might think that Nestlé should be limiting its water use? But it isn’t that simple. The District of Hope gets its water from a number of sources only one of which is the KawKawa Lake sub-watershed (the aquifer shared by Nestlé) and thanks to the large watersheds areas and low population densities in most of these aquifers drawdown is not significantly exceeding inputs. As indicated at the District of Hope web site:
Although water supplies appear to be abundant, the costs associated with the delivery of water to your residence weighs heavily on our infrastructure system. By reducing the demand for water the District of Hope will reduce costs and extend the life of our pumps that pull the water out of the ground providing you with fresh consumable drinking water. Water conservation is our number one priority to ensure ample water not only for today’s customers but for generations of customers to come (ref).
As for Nestlé, in 2012, corporate affairs spokesperson John Challinor said, Nestlé withdrew 71 million gallons (ref) in its operation. Now that sounds like a lot until you put that number into perspective. Regular readers of my blog will remember my post How Big and Small Numbers Influence Science Communication Part 1: Understanding Fuel Spill Volumes where I discussed the “Olympic-sized swimming pool” as a measure of volumes used to scare people about oil spills. Well 71 million gallons translates to approximately 268 million litres of water which is just under 108 Olympic-sized swimming pools (OSPs).
The Kawkawa watershed system, upon which the aquifer used by Nestlé draws, includes Kawkawa Lake which is approximately 1 km long by 1 km wide (ref). That represents 1 billion litres of water for each meter of depth in the lake and that is only the stationary storage since the lake draws from a watershed that is many square kilometers in area. As I described above, when an unconfined aquifer is hydraulically connected to a surface water body (KawKawa Lake in this case) then the aquifer would only be at risk if the Lake were at risk, but as pointed out in the Tyee article Nestlé draws less than 7/10th of one percent of the available water in the sub-watershed. That is a rounding error even in the driest of years. As described in their documentation, Nestlé has been operating for 15 years at this location and they have seen no effects on Kawkawa Lake. Rather excess water from the lake continues to flow into Sucker Creek and from that into the Coquihalla River and ultimately the Fraser River. To put this volume into perspective, the Fraser River has an average flow rate of 3.745 million liters of water per second (ref) so the amount of water extracted by Nestlé in a year is about 72 seconds worth of water flow from the Fraser River as it passes Hope. So to answer the question, does the Nestlé operation put the aquifer at risk? Absolutely not. If Nestlé stopped operating (and put its 75 employees out of work and stopped paying municipal taxes) would there be more water for the rest of us? Absolutely not. Kawkawa Lake drains its excess water into the Fraser River, which simply drains into the Strait of Georgia. Neither the Fraser River at Hope nor the Strait of Georgia are particularly short of water even in the driest of years.
To be clear here, I am not saying that Nestlé shouldn’t be paying more to extract groundwater from the aquifer, but that is a matter for our elected government to decide. What I am saying is that the operation of the Nestlé plant in Hope would not appear to be affecting the local water supply in Hope, the greater water supply of the Fraser Valley or the even greater water supply of the Lower Mainland. Nestlé’s water supply is completely independent of the water supply used by you and me in Metro Vancouver and not a single litre of the water bottled in Hope would otherwise be available to the users in Vancouver dependent on the Metro Vancouver Water system. The only reason to deprive those 75 people of their employment and the District of Hope of those tax revenues, during this drought, is to make someone else suffer in order to make ourselves feel better and that is not a very reasonable basis for a policy decision.