A watershed is defined by National Geographic as “an area of land that drains or ‘sheds’ water into a specific waterbody. Every body of water has a watershed”. (May 19, 2022). The figure below is a cartoon of the hydrologic or water cycle.  Precipitation typically falls to earth as either rain or snow. Over time, a portion of the precipitation will be returned to the atmosphere through evaporation or by plants’ transpiration (releasing moisture through their leaves).

In our environment, most precipitation falls on the ground where it either soaks into the ground or flows into wetlands, streams, rivers, lakes and the ocean.  Wilderness watersheds or undisturbed watersheds have, over the ages, been able to take in and use water or to slow it as it moves towards wetlands, streams, rivers and lakes.  The plants, fungi, animals and insects benefit, and the land is able to withstand naturally occurring seasonal drought and floods.

The above image is from:

  In an undisturbed watershed, trees, undergrowth, leaves, and a few inches of built up duff or decomposed material over the soil slow the water and promotes natural infiltration of the surface run off into the soil. The water then percolates down, sometimes only as deep as the ground saturation point, which we call the water table, or as deep as the aquifer below. Any excess runs off slowly or quickly, depending on the type of soil and how able the soil is to absorb water, the vegetation in the area and the amount of rain falling. Along the coast there is also natural drainage from the soil into the ocean.

Watersheds in our area:

Understanding the viability or successful working of the hydrologic cycle is critical to the health and wellbeing of communities on southern Vancouver Island, including ours. When we put in a ditch, a culvert, a road or a building, we affect the watershed and all that it reaches.

The CRD has over 300 recognized watersheds which are over 200 hectares in size and many smaller watersheds, both named and unnamed. Figure 2 below is a link to the CRD 2015 map of the watersheds of CRD area with the names of the creeks. To read it more easily, enlarge it.

The key in the left-hand corner of the map shows watershed boundaries, natural drainage, wetlands, ditch assisted and urban type storm drain networks among other interesting features.  

Figure 3, the next link, is to the CRD watershed maps page which shows some, but not all, of the individual watersheds with the ground cover, state of development and state of health of the watershed. It is a representation and not exact. While the map is coloured for trees, it does not make clear whether the trees are sparse or thick.  Click on the link, then choose and click on the water system you want to look at.

The last map, shown in figure 4, is of the Juan de Fuca soil infiltration potential which shows where the soil takes in or absorbs a lot of water or sloughs it off in predominantly rocky areas. Infiltration is important to provide moisture for all the wildlife, to prevent wild fires and moderate their spread and to let water seep down to the aquifers below.

Discussion : The maps represent many years of historical data collection and appear to show many creeks and flow rates of water. However, during the last two long dry summers the west side and the east side of southern Vancouver Island and the Gulf Islands were in LEVEL 4 and 5 SEVERE DROUGHT condition. Our area is third from the bottom on the chart linked below. Scroll down on the left side to see the chart and it is possible to enlarge the chart.

Figure 5 below is a Boil water Advisory for Saturna Island.

Two types of significant activities related to urban development include: (a) development of structures such as homes and commercial buildings and parking lots that cover large areas that were once centers for natural infiltration of precipitation and, (b) building of large, complex water diversion structures that capture the natural precipitation as waste-water and funnel it either into major rivers or into the sea.  Thus, urban development in the CRD significantly affects the ability of the natural hydrologic cycles to capture and control the precipitation that our communities depend upon for safe drinking water. The rain that lands on the roofs is thought of as “waste water” and foolishly not valued nor allowed to stay on the land where it falls.

In urban areas like malls, the watershed problem is even worse as there is no chance for the water to sink into the ground since it is all paved, and pollutants wash off the paving into the drains and eventually into streams, lakes or the ocean. Even in rural areas we have seen the effects of rain flowing down a long-paved driveway onto the road. It gets even more exciting when the temperature drops, and it freezes. We need to think about the watershed and the effects of what we do before we do it, from digging a ditch to drain land, clearing off trees to putting in a long-covered culvert or building a dam.

We have been told by some Langford farmers that they are really struggling with trying to earn a living as the development logging and blasting means that the rain is not held on the land above the farms. This results in the surface water not being absorbed by the soil and flowing as run off and pooling on the land below, so the fields are too wet to plant until later in the spring and in the fall. This means planting is late and the fall rains run off and pool too soon for harvesting some crops.

Even the removal of a few trees can cause problems when heavy rains come if the removal is not well thought out. We have all seen the roads and bridges that washed out last year in the province. You may have noticed the plastic netting that the road construction crews placed on some of the banks by the highway improvement project to keep the soil from washing down onto and across their new road.

Not in our area but examples of ill thought out actions on watersheds are shown below with the work that is being done to correct damage.

A downside to human made dams is not thinking about what else the dam affects other than water retention or flood prevention. Elk Lake / Beaver Lake in Saanich was dammed in the 1870s to prevent downstream flooding of farms and to provide drinking water to the young City of Victoria.  It is the headwaters of Colquitz Creek. All people considered was the water flow and not the fish or the health of the water in the lakes.  The CRD has since replaced the dam with a fish ladder and a spillway which better controls the flow and provides access to the lakes for fish. However, the lakes now suffer from algae bloom which affects the water and plant life in the area. A 2021 Saanich report noted the excess of nutrients, particularly phosphorous, from waste which is in the surrounding watershed and pollution from the highway are a large part of the problem.  Colquitz Creek which flows from Beaver and Elk Lakes in Saanich is getting the extensive remediation work done and it will take years to return it to health.

  Bowker Creek, which runs through Saanich and Oak Bay municipalities has had a group of volunteers and local government working to “daylight” and clean up the pollutants from the Creek and make it attractive to the chum salmon which used to be plentiful.  Much of the creek was polluted and ran through long culverts which did not allow for the natural plants, birds and animals to live. Thanks to the work of the project, the natural life is now returning.


Many towns are now encouraging people to use rain swales or hollows planted with native plants in their landscaping to slow the runoff and keep the rain where it belongs. A water expert spoke to OPSRRA several years ago and he maintained that we should all think of naming our ditches and creeks so they can be identified as a valued part of our watershed.  Perhaps if we thought of our ditches in this way, we would be less likely to put potential contaminants into them. Do you know if your ditch feeds into a stream where someone may be using that water downstream for their water source?

There is a story about a little stream that came out by the side of the old Island Highway, trickling all year long. Someone rocked it in and people would stop to get a drink or fill up bottles, saying it was the best water they had ever tasted. Years later, people wondered about the source of the stream and followed it upstream to discover that it went to a farm, and plenty of manure washed into the stream. Needless to say, the little rocked in collection place by the highway was removed.

Natural dams and lakes act as buffers to any quick diversion of water, slowing down and holding it on the land.  Artificial dams and reservoirs found at Sooke Lake and Goldstream stop and hold the water for all the distributed CRD water in the CRD area. Dams can also prevent sudden flooding events. 

The watershed for the CRD drinking water at Sooke Lake is the only watershed in Canada which bans all entry to the watershed land area.  It is therefore well protected from outside contamination. No other area on the south island can really claim this and thus we must watch carefully where we place developments such as roads, housing and farming so that contamination of water is avoided.

  Peninsula Streams and Shorelines Stewardship Programs have been operating since 2002 in 13 of the watersheds in Greater Victoria.  Their volunteers work with anglers to monitor and improve the watershed and stream systems all over the GVRD.  From their webpage: “The objectives of these collaborative partnerships are to: educate the public about the importance of watershed resources, to facilitate communication and cooperation in watershed management and to provide volunteers with the training required to protect and restore aquatic and riparian habitat.” In addition, “Our dedicated stewards are also the ‘eyes and ears’ of local watershed conservation, monitoring stream conditions, counting salmon and alerting authorities when there are problems with local streams.”


Attention to and concern about sensitive ecosystems and protection of groundwater and groundwater supplies are not new to our area or to OPSRRA.  Bob Phillips did a well researched report for OPSRRA in 2014, and previous to 2008 people in our area have been concerned about the health of the environment. In the face of less precipitation and more development, we need to educate ourselves and make the best choices. Lives, not only human, depend on it.

The South Island area is about ten years behind the residents of Salt Spring Island and most of the other Gulf Islands in awareness and concern about water.  Salt Spring Island Water Protection Alliance

 ( SSIWPA) has a well developed team of volunteers that, among other activities, monitor the watersheds and streams of their community. They are well organized and very helpful to groups seeking to learn more.  They have several good videos on water, watersheds, rainwater harvesting and storing that are relevant to our area as well.  The newly formed water interest group here, the 606 Water Group, is very grateful for their help in trying to increase interest in water and watersheds in this area.

Does anyone know if the CRD west of Sooke has a coordinated volunteer group like this to monitor the hundreds of streams and watersheds that exist on our coast? Baseline information is important on all watershed areas, as well as on fishery streams.  Collected and recorded data will show us the changes being made by the climate.  When does the stream stop flowing in the summer?  When does it start in the fall?  What is the impact on water flow, habitat and animals?  What is the health of the stream?  The answers to these and many other questions will help us to manage the use of watersheds and keep them in healthy operation during the coming years.  We as an area need to encourage residents to become watershed stewards and to adopt a local watershed to monitor. If we have an organized volunteer group, we can get funding for training to assess the health of our watersheds and over time we will build a database of information to help us keep watch on the health of our land.  Please make yourselves known.

Submitted by   606 Water Group  

S.Atkin, K.Zeiler, & L. Moss

One thought on “Watersheds

  1. I was just talking with someone who is at the base of Broom Hill about how the developments up there have caused flooding on her property.


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