Water Quality in the Salmon River/Hopington Aquifer

(from a letter to Langley Township Mayor & Council, dated August 14, 1998)

The Salmon River Enhancement Society has been testing water quality in the Salmon River and tributaries regularly for over 2 years. Our recent tests give us continuing cause for concern as the nitrate level in Coghlan Creek in Williams Park on June 6, 1998 was 8.7 mg/l and on July 23 was 9.8 mg/l. As you know, these levels are very close to the Public Health limits for drinking water of 10 mg/l. (Coghlan Creek in Williams Park is the purest test for ground water as it has the greatest proportion of its flow from small springs originating in the aquifer. Since the aquifer is cooler than surface flows, the Coghlan is also the coolest part of the Salmon River system. The dry weather and lack of rain/surface water runoff into the river mean that samples taken at this time of year are more representative of the actual ground water or base flow from the aquifer.)

Studies have indicated that nitrate levels are high due to infiltration of manure and fertilizer from the surface through the very permeable sand and gravel layers lying over the Salmon River/Hopington Aquifer. Nitrate levels are used as an indicator for other pollutants such as herbicides and pesticides which are difficult to test for but tend to be seen in combination with nitrate. The "Ground Water Quality Assessment of 1996" by Dr. Hans Schreier  suggested that approximately 1/3 of nitrates are from hobby farms, 1/3 from other agricultural uses and 1/3 from septic tanks/fields.

We have been encouraged by work done by the Township to develop a septic tank brochure (several of the founding members of our group were actively involved in developing this brochure) and work done by the Ministry of Agriculture to develop guidelines for farmers. It does appear, however, that some sort of more active contact with landowners will be required to distribute and implement this information in a way that creates an impact and changes behaviour. Since the majority of the problem is related to agriculture, efforts in this area would provide the maximum benefit. We believe that significant improvement in water quality could be achieved. We may also need to look at European practices where agriculture and hobby farms must either limit their animal density or have a manure management scheme in place.

While septic tanks are a smaller portion of the problem, our society continues to support the idea of a Septic Tank Maintenance Bylaw as regular maintenance of septic tanks is an easy way to reduce some of the nitrate load at a relatively low cost (about $100 per tank every 2 or 3 years). An educational campaign is still a good idea but we question how effective it will be in changing behaviour as people are so busy that they tend not to get around to having the septic tank cleaned until it is too late. We know of a case where a person in the public health system, and therefore having more than adequate knowledge, just didn’t get around to cleaning out the septic system and had to spend a much larger amount to have the field replaced.

An alternative to a Bylaw might be a system where a landowner would be given a tax rebate if they have had their septic maintained within the last 2 to 3 years. Perhaps the companies that perform the work would be interested in giving a discount to those participating in the program. The landowner would then have an incentive to get the work done, they would have to pay a very minimal amount and their septic system would last much longer. Since the Salmon River Watershed is being recognized as a "demonstration" watershed, a new program of this sort might be an appropriate trial.

Finally, we note that the moratorium on development over the Aquifer is being reviewed. Our samples would suggest that water quality is still marginal and therefore that further development is not advisable. We must be careful as it is estimated that it takes at least 5 to 10 years for changes on the surface to be reflected in ground water quality in wells deep in the aquifer. Even if the septic tank part of the development problem were solved, development could also lead to increased nitrates, herbicides and pesticides from lawns and gardens as studies indicate that urban landowners use larger quantities per acre of all these materials than do farmers. In addition, development creates problems with rapid runoff during rain events and increased flooding downstream such as in the Fort Langley floodplain. 

(author:  Doug McFee, B.A.Sc., MD, Chair, Salmon River Enhancement Society)