Money Lake - photo by Al Razutis 2005
SATURNA WATER CONSERVATION COMMITTEE
The Saturna Water Conservation Committee is the new name of the Saturna Groundwater Protection Committee. It is a committee of the Community Club. The new name reflects the emphasis on promoting individual responsibility for water conservation as well as our ongoing concern about protecting groundwater sources.
Collection and use of rainwater flows naturally (sorry, couldn't resist) from reduction of well-water use. The committee is eager to encourage rainwater collection.
The Long Term Hydrochemical Monitoring Program
The study is under the direction of Dr. Diana Allen, of Simon Fraser University. The first year of the study is providing a baseline against which to measure changes over the next ten years. Now samples are collected every six months. This study has an immediate benefit to islanders in that it is monitoring for the development of saline intrusion into wells.
Saline intrusion occurs when there is an excessive drawdown on a well, and salt from the surrounding ocean finds it's way in. It is most likely to occur in wells close to the waterfront. It can mean that the well water is no longer potable without extensive and expensive treatment. The results of Dr. Allen's study can be found on her website at www.sfu.ca/earth-sciences/faculty/Allen.
It now explains, in terms understandable to non-Hydrogeologists, how to interpret the results of the testing. These cumulative results are posted on Dr. Allen's website, & can be accessed by clicking on the link below. To look at the specific results for the different island study areas just click on the "box" enclosing the area of interest. Any well owner participating in the study can contact me for the code ID of his/her own well.
The link is:
What is it, & why is it a threat?
Surface water is separated from groundwater by the filtering action of the local geology. This filtering is usually a very effective way of removing surface bacteria from the water. Many well-constructed wells accessing groundwater produce water that is biologically safe to drink without treatment although regular testing is recommended.
Science has demonstrated that the groundwater underlying Saturna is derived from the rain that falls on the island. This fresh water zone can be pictured as a bowl, and it is the source of the wonderful water that some wells deliver.
However, Saturna sits in an ocean of seawater that tends to permeate the seabed and the island geology. Thus there is saline groundwater outside the bowl, and a dynamic interface between the fresh and the salt water. This is very well illustrated on the poster of the Gulf Islands Waterscapes, and on the placemats available from the committee.
Saline intrusion has occurred when your well starts to pump up salt water. This is a problem because the water is not drinkable without treatment, and is not suitable for use as utility water.
How does saline intrusion occur?
A well that is drilled too deep in a search for water can drill beyond the bowl of freshwater into the salty groundwater. This is more likely in wells drilled close to the foreshore, and where fissuring allows rapid travel of water through the rock.
However, there are other cases.
A good well, delivering fresh water, can become subject to saline intrusion. After a dry winter, with little rainfall the fresh groundwater zone (or bowl) will tend to shrink and the salt-water move in. Thus the well might start pumping salty water.
Finally, if an owner over-pumps his well salt-water may finally be sucked in locally, producing the condition of saline-intrusion. Over-pumping exhausts the local fresh water and salt water is drawn in when the bottom of the well is close to the interface.
What can be done about saline intrusion?
Many authorities would recommend that the well not be used, and be capped. It is possible for a well to recover, but the process may take many months or years.
What about desalination of salty well water?
This is possible, most commonly by reverse osmosis. Unfortunately, the yield of freshwater produced is only about 20% of the total water treated. Ironically, the need for fresh water can actually increase the over-pumping of the well; & this may have negative effects on your neighbours. Moreover, 80% of the water treated is hypersaline, and needs disposal. When put on the land this may be an excessive mineral load for plants. It is best returned directly to the ocean, & this may be difficult. Reverse osmosis is also fairly expensive at present, & requires a good deal of electrical energy to produce the high pressures needed.
The moral of this story?
If you have a good well, cherish it. Conserve water whenever possible. Consider augmenting your supply of water by rainwater collection. There is increasing local expertise available about this. If you suffer the misfortune of experiencing saline intrusion best bite the bullet and cap the well. Drill another well by all means if you can afford it. Best of all perhaps is to consider using rainwater for all your needs.
Saturna Placemats now available!
An entertaining & educational way of understanding the importance of water conservation on this island. Colourful and durable. Derived from the Gulf Islands Waterscapes project. Reflect current best scientific evidence.
Every Saturna household needs to be familiar with this information, & to pass it on to visitors. Each set tells, in sequence, the story of the circulation of water on the Gulf Islands, & the risks of bad practices.
Available in sets of 4 or 8, with the same content in both.
Matching funding from the Saturna Community Club & the Islands Trust makes this possible at below cost. Make cheques payable to: Saturna Water Conservation Committee.
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2003 Archives - Ground Water Protection