The scope of loss when it comes to wetlands affects more than just migrating waterfowl. The Southern Interior has become the most densely populated part of B.C., with more communities added every year. In the Okanagan Valley alone, human activities have resulted in the loss of 85 per cent of the wetlands along the valley floor. It’s also degraded the water quality in local lakes and streams.
Over the past century, the intense pressure on the Okanagan Valley has taken its toll on wildlife. Only about two per cent of valley-bottom wetland habitats are considered to be in an undisturbed state. The Okanagan River was channelized and diked in the late 1950s. That resulted in cutting off the natural water supply to most floodplain wetlands and drastically altering the natural flood regime of the valley.
Ground observation and aerial photos reveal where the natural swales and oxbows had formed and where saturated areas continue to exist. During spring freshet, most of the land is still inundated with water and wetlands are recharged. However, the effect is temporary.
Building wetlands with a purpose
DUC is working to restore what has been lost. DUC recently completed a project in the South Okanagan. The restored wetlands will provide habitat for species at risk, which have been particularly hard-hit in this part of B.C.
DUC owns a property in the South Okanagan, south of Oliver, known locally as the Winters Property. It’s adjacent to the Okanagan River and has an old oxbow running through it, mostly isolated from the river channel. In 2002, DUC purchased the property for $400,000 with funding from the North American Wetlands Conservation Act. In the mid-2000s, DUC worked with an amphibian specialist to excavate several small ponds to support breeding “Great Basin Spadefoot Toads,” or spadefoots. In subsequent years, DUC removed the house and outbuildings and reconstructed the pasture fencing.
Earlier this spring, DUC excavated nine new small wetlands aimed at providing habitat primarily for spadefoots, but also for tiger salamanders. Both are species at risk in British Columbia.
Slopes were designed to be more gradual on one side as spadefoots prefer warm, gentle southwestern slopes.
If you build it, they will come
“Old oxbow depressions were targeted, to provide the most certainty that some water will remain throughout the yearly cycle,” says DUC biologist Bruce Harrison.
Harrison says pond depths will provide at least three feet of water during the annual low water period in January and February.
“Slopes were designed to be more gradual on one side as spadefoots prefer warm, gentle southwestern slopes,” says Harrison.
He says there are some deeper, permanent water areas and shallow areas that possibly dry out by late summer.
Wildlife benefits for the Intermountain Region
Providing habitat for species at risk was a priority in this project. However, the new ponds will also benefit waterfowl and other wildlife. More than 25 waterfowl species have been documented in the South Okanagan. These include mallard, wood duck, cinnamon teal, redhead, hooded merganser, Canada goose and trumpeter swan. Other species of concern such as painted turtle also inhabit the property.
DUC’s vision for the South Okanagan, which falls in the Intermountain Region, is a landscape that supports healthy populations of birds, maintains biodiversity and fosters sustainable resource use.
Harrison says this project provides regionally significant breeding wetlands, which move us closer to achieving that vision, in a location that also serves as a migration staging point for waterfowl moving through and within B.C.