city-services

Creek Bank Stabilization

The City of Morden is working in partnership with the Pembina Valley Conservation District (PVCD) to inform residents along the Dead Horse Creek as to what activity is permitted and what is detrimental to the creek bank and adjacent area. This initiative is geared to ensure creek bank stabilization now and in the future.

City Property

Morden belongs to the PVCD and has two appointed members that are part of the Dead Horse Creek Sub-Committee. This Sub-Committee considers all work along the creek and identifies the priority areas. PVCD has the knowledge and expertise to determine what kind of work is required to stabilize the creek bank. They are working with the City on the public areas, have cost shared erosion control measures in the past, and are planning some bank stabilization work for the future. When developing along the creek bank north of the Parkhill bridge, the City has maintained ownership of the property directly adjacent to the creek in order to ensure creek bank stabilization and allow access when required. If you are unsure of your property lines please call the Morden Civic Centre Office at 204-822-4434, or review your survey obtained at time of purchase.

Private Property

On privately owned sections of the creek bank PVCD will provide advice, surveying and design services and assistance with acquiring permits, etc. There is no cost to the landowner for these services, although there is no commitment for providing funding for construction or other remedial measures. In very dire or high risk circumstances the landowner may be advised that they should hire the services of a geotechnical engineer. There is no funding from PVCD or the City of Morden for these special or extra services.

Main Messages for creek bank areas;

  1. No management of City property is allowed without permission from the City in writing. This includes: planting, mowing, vegetation removal, burning, spraying, berming, earthworks, placement of sheds or benches, landscaping, terracing, fire pits etc.
  2. Berms are permitted on private property. PVCD recommends that any berm be set back from the river bank a minimum of 3 meters. The additional weight of a berm on the creek bank may cause the side to cave in.
  3. Pesticide and fertilizer use is not permitted on City property.

CONTACTS:

Pembina Valley Conservation District (PVCD)
Box 659, 261 Main Street
Manitou, MB, R0G 1G0
Tel: (204) 242-3267
Fax: (204) 242-3281
Email: pvcd@goinet.caWebsite: www.pvcd.ca
Fisheries & Oceans Canada
Winnipeg District
501 University Crescent
Winnipeg, MB, R3T 2N6
Tel: (204) 983-5163
Fax: (204) 984-2402Website:
http://www.dfo-mpo.gc.ca/managing-fisheries-habitats-eng.htm

Why No Mowing Zone beside the Creek?

These are some things that a healthy riparian zone does for you – Reduces Stream Horsepower and wave energy / Strengthens banks / Creates a sponge like bank that absorbs and releases floodwater slowly /  Captures sediments

These are accomplished by a healthy diverse  riparian zone.  This will limit creek meandering and threats to homes and land beside the Dead Horse Creek.

What is the Riparian Zone?

The Riparian Zone is the land beside the water that is affected by the water. It separates the water from the upland. This is the area that should not be mowed along with a buffer along the riparian fringe and upland. The upland with larger trees provide structure and strength to the bank and intercept surface water and lower groundwater in this area.

Biodiversity is Strength & Protection

Biodiversity is important because this approach provides the most protection against erosion.  Species diversity in a riparian zone  ensures that there are always plants thriving to protect and keep the banks together.  Mowing will favour some plants and limit others success so mowing will result in a monoculture that is the opposite of diversity.

Like an Iceberg There is a lot Going on Below

Keeping riparian plants mowed weakens them because their energy comes from the sun and also they grow from “Growing Points” that when continually clipped limits their ability to gather and store energy.  The above ground part of the pant is the solar collector and the better the solar collector the more energy the plant has to grow roots and seek the water and nutrients it needs.

Slow Down the Runoff with Vegetation

While the roots bind the soil together the above ground plant material slows down the flow and encourages building of banks rather than eroding.  For example if the Winnipeg flood-way was paved it would transfer twice the volume of water that it does today while it is in short grass.  Surface roughness has a tremendous impact on flow velocities and water movement.  The slower the flow the less risk of erosion.

Narrow and Deep Vs Broad and Flat

The vegetation beside the waterway can dictate its shape.  The more stable and desirable shape is narrow and deep.  A broad flat stream has lost it’s lateral stability and has more potential to erode, meander and threaten adjacent properties.

Vegetation Intercepts Groundwater that is Moving towards the Creek

Vegetation beside the creek, the trees, shrubs and grasses intercept water coming off the lad on the surface and in the ground.  Without this stabilizing force and withdrawal of groundwater the banks would become very unstable and susceptible to slumping.  In this case any rock armouring will not be effective because the banks are failing from within.

Creeks Move

Most creeks and rivers are serpentine in shape because of the very core nature of water moving over the landscape.  Most creeks move laterally in the floodplain over time and it is a natural process.  This shifting can happen over generations if proper vegetation is in place or when creek-side vegetation is removed and the stream loses its natural protection then this process is speeded up.  A slow process that may be 2’ of erosion or bank movement per year on average can change to ten times that  without vegetation.

Rip Rap Rock Needs Some Help

Rock Rip Rap is often used to stabilize banks.

The rocks and other hard armour get weaker over time and can’t do it alone.  This type of bank protection relies on the ever increasing strength of plants to keep the banks from slumping and eroding.  The roots tie it all together and the surface material offers resistance to flow.

Nature is messy?  We need to train our eyes to appreciate biodiversity.

Mother Nature produces plants in all shapes and sizes, colors and smells.  The natural tendency is to yearn of nicely manicured gardens with a precise blend of cultured horticulture.  This may not work great for bank stability.  Nature appears messy and chaotic but that variety provides landscape strength.  Healthy riparian zones are best left in a natural state.  This provides the best protection for property beside the creek.

 

Why No MOWING Zone?

Trying to avoid this! –

For more information on how to protect your creek bank call the Pembina Valley Conservation District at 204-242-3267 or look at their website at www.pvcd.ca

Pictures and information came from a variety of sources.

  • Cowns and Fish Program Literature
  • Managing the Water’s Edge Literature
  • Ag Canada
  • The Manitoba Habitat Heritage Corporation
  • MAFRI Agro-Woodlot Program

Many thanks to these groups for this valuable information.

Creek Bank Planting

If there are erosion issues, we strongly recommend using some willows along the bank; other species may not have a chance to become established, plus they are the most cost-effective. You could use them to first stabilize the soil and help get other species established. What we don’t want is for a lot of money to be spent on trees that get washed away the first spring. Naturally, the “nicer” trees and shrubs come in after the cottonwoods, willows and maples have done their thing first.

Trees:

Manitoba Maple, American Elm, Green Ash, Basswood

Taller Shrubs: (of course willows would be #1)

Red-osier Dogwood, Canada Plum, American Plum, Nannyberry, High-bush Cranberry, Pincherry, Saskatoon, Hazelnuts, Chokecherry

Lower shrubs:

Raspberry,  Gooseberries/Currents,  Meadowsweet

Grasses/graminoids

Sedges,  Cordgrass (Spartina sp.),  Reed grasses (Calamagrostis sp.),  Switch grass,  Fowl bluegrass (Poa palustris),  Mana grass (Glyceria sp.),  (other than maybe the cordgrass and switch grass, these will be difficult to obtain commercially; you may have to look at harvesting from other areas?)

Forbs/Wildflowers: (typically a small component of the understory; not likely available commercially)

Cow-parsnip,  Starflowered-false solomon’s seal,  Canada anemone,  Sweet scented bedstraw,  Peavines,  Wild lily of the valley,  Strawberry

Three Zones For Planting

Separate the area into three zones;

  1. the channel shelf (area up to the high water mark),
  2. the transition zone, and
  3. the terrace.

Each zone experiences a different moisture regime in terms of the duration and intensity. For example the terrace area may experience water flows during an “event” and for only a short duration where the channel shelf area will experience higher intensity flows for a longer duration.  As expected each zone has an optimal tree/shrub species and as you move away from the high water mark your species options increase. The following is a list of recommended shrubs and trees by zone:

Channel Shelf Transition Terrace
Willow (Sandbar) Red Osier Dogwood Birch
Red Osier Dogwood Willow Maple
Red Elder Cottonwood Ash
Maple

If you a looking for information that best illustrates the zone concept and what species grows where, Manitoba Conservation Forestry Branch has a “Managing Riverbottom Forests pamphlet

http://www.gov.mb.ca/conservation/forestry/pdf/practices/riparian_mgmt_final_sept2009_.pdf