"Committed to the restoration of wild Pacific salmon in mid Vancouver
Island watersheds through habitat restoration and community engagement"
"Committed to the restoration of wild Pacific salmon in mid Vancouver
Island watersheds through habitat restoration and community engagement"

Shelly Creek Water Balance and Sediment Reduction Plan

 In 2015, volunteers completed a survey on the upper section of Shelly Creek using the  Urban Salmon Habitat Program (USHP) protocol . The results showed that much of the 2 km of creek above Hwy 19 has been excavated. This has resulted in significant changes to the natural hydrology of the watershed that have heavily impacted the lower section of Shelly Creek which supports a resident Cutthroat Trout population and overwintering Coho Salmon fry and smolts. These impacts became evident when the USHP conducted on the lower section of the creek in 2014 was compared with a USHP conducted in 1999. The comparison of USHP results for the the lower section of Shelly Creek show there has been:

  • significant increase in erosion of stream banks
  • significant increase in the amount of fine sediment covering the bottom of pools
  • 50% reduction in the number of pools (due to infilling by sediments)
  • less cover for fish
  • less gravel for spawning
  • a high number of obstructions of fish passage during low flow

Without restoring the natural hydrology of the creek, any fish habitat restoration or mitigation we complete may not be successful. MVIHES retained Mr. Jim Dumont, a Hydrological Engineer, to conduct a water balance study that compares the current water flowpaths in the Shelly Creek watershed with pre-development flowpaths. From this study we hoped to find the root cause of the increased erosion and sedimentation, and methods for correcting the problem. 

Interflow

When we think of water flowing into creeks, we often think of surface flow that takes only minutes or hours to enter a creek, and groundwater flow that may take years to reach a creek. What we may not be aware of is interflow. When water sinks into the ground we often assume it is all going into the groundwater aquifers, however, much of it actually travels horizontally through shallow soil layers into the creeks. In fact, interflow is the primary pathway for water flow in an undeveloped watershed in coastal BC. It typically accounts for ¾ of the annual volume that reaches a stream. Interflow take days and perhaps a season to reach a creek and is important because it supplies water during dry spells.

Several things can and do interfere with interflow in the Shelly Creek Watershed and are associated with development. One is impervious surfaces such as buildings, pavement and concrete. These surfaces prevent precipitation from penetrating the soil to supply interflow. Most of the precipitation that falls on these surfaces becomes surface flow that enters and exits Shelly Creek over a short period of time, leaving the creek with almost no water during dry spells. Drainage ditches built along roads and in residential areas intercept interflow and turn it into surface flow which is directed into Shelly Creek.  This increase in surface water flow during rain events is what is causing serious erosion and sedimentation problems. In fact, the water balance study shows the duration of flows that cause erosion (1 L/s/ha to 8 L/s/ha) has increased by more than a factor of 5 since pre-development. If development within the Shelly Creek Watershed continues in the same manner, the duration of erosion-causing flows is predicted to increase by 14-fold, a devastating outcome for Shelly Creek.

Why is development that impacts interflow to Shelly Creek happening?

Standard drainage engineering practice only considers surface runoff. The other two pathways (interflow and groundwater) by which rainfall reaches streams are ignored. In short, drainage engineering practice lags behind real-world hydrology, and as a consequence Shelly Creek is experiencing serious erosion and destruction of fish habitat. 

An alternative to standard engineering practices is using a Water Balance Methodology that accounts for all three flow paths with the goal of keeping all three flow paths in balance. The good news is that there are already tools available to accomplish this. The bad news is that they are not being used. So what can be done to correct the problem? 

interflowmapEnforce Ministry of Transportation and Infrastructure Design Guidelines A majority of future subdivision will occur within the RDN where Ministry of Transportation and Infrastructure (MOTI) is the review and approving agency for subdivision and drainage design. MOTI Guidlelines already exist that require drainage and development plans be designed to prevent the downstream flows that have impacted Shelly Creek. But they are only guidelines, not regulations. Nonetheless, MOTI should enforce the guidelines to future subdivisions. The City of Parksville  should adopt similar standards.                    

Utilize Water Balance Express for Homeowners for all Future Building Applications  The Water Balance Express for Homeowners is a computer application created by the  Partnership for Water Sustainability for British Columbia to provide guidance in restoring site conditions to their natural hydrologic function. Implementing the Water Balance Express within the building application process will require changes to the administrative processes for building permitting in both the RDN and the City of Parksville. Both organizations will require bylaw amendments, or new bylaws to allow the implementation and ongoing maintenance of rainwater management systems on private property. We anticipate the construction and certification would occur as part of the building permit and construction process.    

Encourage Homeowners Within the Shelly Creek Watershed to Return the Hydrology of Their Property to a Natural Condition  This involves the mitigation of impervious areas such as roofs and driveways, sidewalks, and patios with the use of rainwater retention that can be in the form of raingardens, infiltration ponds or other landscaping features that contain and slowly release captured rainwater from the impervious surfaces.  The Water Balance Express is a useful tool to assist with this. The Regional District of Comox has a version that can be viewed at   http://comox.waterbalance-express.ca/     

Buidling support for action begins with community engagement. No doubt MVIHES has a challenge ahead to build consensus among our community, the developers and government agencies for a new approach to development and drainage management if we are to save the remaining fish values in Shelly Creek.

OUR SPONSORS 

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 We acknowledge the financial support of the Government of BC

  

Further Reading

Shelly Creek Water Balance and Sediment Reduction Plan - Technical Summary

Shelly Creek Water Balance and Sediment Reduction Plan - Phase 1 Physical and Environmental Investigations

Shelly Creek Water Balance and Sediment Reduction Plan - Phase 2 Computer Modelling and Assessment

Shelly Creek Restoration

Shelly Creek Information Sign

MVIHES has received a grant from Recreational Fisheries Conservation Partnerships Program to conduct restoration work on Shelly Creek at the top of Blower Road in Parksville. The objectives of the restoration work are to prevent more sediment from filling in the valuable fish rearing areas of lower Shelly Creek while improving fish habitat upstream through bank stabilization, channel stabilization, fish passage improvement, instream complexing and riparian planting. Right now there is no flow in the creek so this is the best time to conduct work.  Prescriptions and other preparations for this project were completed in fiscal 2014-15. Pictured is a sign that lists other partners in the project. Be aware that the work is being completed on private property so if you go to view, please stay on the road – that provides the best vantage point anyway.

Day 1 Shelly Creek Restoration

     

 

 

Day 1 – large rock was brought to the site and the first weir was started. Three weirs will be built in total to improve flow, erosion issues and facilitate fish passage. 

 

 

  

 

Day 2 – first weir, and bank stabilization with rock and soil completed 

 

 

 

Day 3 - second weir has begun, channel beginning to take shape 

  

 

 

 

 

James is watering to pack loose soil between the rocks, and it keeps the site safe from fire caused by sparks 

 

 

 

 

 

Day 4 - the second weir is done and the third is being prepared  

 

  

 

 

 

Days 5 – 9 – another couple of weirs under construction. Some finishing touches starting, such as the addition of spawning gravel. It’s looking great! 

 

 

Stay Tuned For Further Developments!

 

Shelly Creek

Background

Shelly Creek drains from the base of Little Mountain in Parksville, BC and flows northeast into the Englishman River, approximately 2 km from the Strait of Georgia. The confluence is located 200 m upstream of the Island Highway 19(A) Bridge. This stream channel is approximately 6.5 km long, draining a watershed area of approximately 5 km². All of the reaches of Shelly Creek have been negatively impacted by agriculture and urbanization.

measuring migrating coho smolt

Resident cutthroat trout are found in Shelly Creek throughout the length of the creek below the E&N rail crossing.  Currently, cutthroat migration is limited because of several man-made obstructions. Coho smolt and fry also inhabit the creek. It is believed they enter Shelly Creek to escape the high flows of the Englishman River during the winter months and migrate back into the Englishman River during the spring to avoid the high water temperatures and low oxygen levels that come with summer weather.

 

Programs

Since 2011, MVIHES has helped to coordinate the monitoring of the outward migration of juvenile coho and other fish from Shelly Creek.  This was done by installing a smolt trap ~200 m upstream from the confluence with the Englishman River.  As many as 8094 coho smolt have overwintered in Shelly Creek before migrating into the Englishman River, which shows the importance of the creek to coho salmon production.

    

 Volunteer assessing the culverts at Butler Road on Shelly Creek

 As part of the Watershed Health and You program, Shelly Creek was subject to an instream fish habitat assessment in summer 2014. Volunteers were trained by Fisheries Biologist, Dave Clough, in the Urban Salmon Habitat Program (USHP) methodology. Shelly Creek was assessed in 1999 by MVIHES members using the USHP so this provided a great opportunity to replicate the study in 2014 and get new volunteers to assess  this important tributary and determine the condition of the habitat after 15 years. The lower section (below Hwy 19) of Shelly Creek was studied in 2014.

The findings of the study were concerning and included a 50% decrease in pools, less cover for fish, significant increase in the amount of fine sediment covering the bottom of pools, less gravel for spawning, significant increase in erosion of stream banks, a high number of obstructions to fish passage during low flow periods, and man-made alterations to the creek.

A geomorphic overview was conducted by North West Hydraulics in Nanaimo who recommended approaches to habitat enhancement for the creek. Shelly Creek Restoration was completed in summer 2015 at the end of Blower Road.  

 This included armouring the creek banks downstream of the culvert with rock to prevent further erosion. Weirs were constructed using rock and geotextile cloth to create pools. The installation of gravel has created spawning habitat. A large settling pond was constructed upstream of the culvert to trap sediment and prevent it from covering the spawning gravel.  And the creek bed was built up to the bottom of the culvert to allow fish passage. In March 2016, swordferns, cedar, salmonberry and red osier dogwood seedlings were planted along the creek banks and in areas that were disturbed by the equipment used to complete the restoration work. 

 In 2015, an USHP was completed on the upper section of Shelly Creek, above Hwy 19. The results showed that much of the 2 km of creek above Hwy 19 has been excavated. This has resulted in significant changes to the natural hydrology of the watershedClick here to read the  complete report, Shelly Creek Stream Assessment and Fish Habitat Survey Report-2014 and 2015.

Flow Obstruction in Shelly Creek

In an effort to understand how these changes to the stream’s hydrology can be modified to improve the stability of the creek, and hence the water quality, MVIHES hired one of British Columbia’s experts on water engineering, Jim Dumont, P.Eng., to study the creek and provide us with a report. The report is complete and is titled: Shelly Creek Water Balance and Sediment Reduction Plan, Technical Summary.

 

Further Reading

Shelly Creek Stream Assessment and Fish Habitat Survey (2014, 2015) Report

Geomorphic Overview and Habitat Enhancement Report 

2016 Shelly Creek Smolt Trap Study

2015 Shelly Creek Smolt Trap Study

2014 Minnow Trapping Report

2013 Shelly Creek Smolt Trap Study

2012 Shelly Creek Smolt Trap Report

2011 Shelly Creek Smolt Trap Report

Connect

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