The demise of the urban creek
Environment / November 22, 2010
The increase in urbanization in recent years has resulted in many challenges for local streams and rivers, including the destruction of delicate ecosystem. Despite the doom and gloom these rockbeds still have a fighting chance.
By Matthew Bosson [travel bureau chief]
Urban Creeks are facing a number of challenges to remain productive and healthy ecosystems – challenges such as pollution, invasive species and human garbage.
Streams and rivers in the Lower Mainland are seeing more abuse then ever, with pollution brought into the creeks via storm water run-off, garbage from illegal dumping and invasive species brought in for home gardens.
These delicate ecosystems are a valuable resource that are home to many species of salmon and trout as well as crayfish, lamprey, stickleback and scuplin according to local ecological experts.
“The single biggest challenge is storm water runoff, which is a fancy term for rainwater and snow melt that pour directly down street drains and into underground pipes that empty untreated into urban creeks,” said Deborah Jones, a Cougar Canyon Stream Keeper volunteer.
“Before urbanization, this water would have soaked into the ground, where plants, soil and soil organisms would filter and cool it,” she said. “Water not needed by plants or other organisms would then seep into the groundwater table, and from there into local creeks, keeping
their water levels stable and their water quality high.”
Peter Willows, a Salmon Habitat and Restoration Project (ShaRP) environmental consultant, commented similarly, “the major ones [issues facing urban creeks] are pollution from untreated water from storm discharge and run-off and water temperature fluctuation”Willows said there are solutions to this problem, “pre-treatment of storm water, by way of mechanical filter systems and natural scrubber marsh systems can be utilized. This detention and slow release of rain water would prevent much damage to local creeks and streams.”
“The biggest single improvement would be for local governments to require that all storm water runoff be directed first into landscaped areas, rain gardens or infiltration swales,” said Jones.
“This would allow cooling, filtration, and groundwater recharge to take place, as they once did in pre-development landscapes.”
Aside from the issue of pollution, there are several other problems facing these fish rearing habitats.
“Other significant challenges to urban creeks include invasive plant species and human/dog traffic, both of which transform the ecology of riparian [stream side] habitat,” said Jones.
“Native plants and animals create a very particular soil chemistry, water chemistry, insect population, etc, all of which are ideally suited to healthy streams with healthy populations of our iconic Pacific Northwest fish, salmon and trout.”
Jones said the appearance of foreign plant species such as English ivy, Lamium, Daphne, Laurel, and Japanese knot-weed in the Lower Mainland limits the growth of native plants that would have traditionally shaded the stream, which helps control water temperature and increases the creeks ability to hold oxygen, according to the Metropolitan Sewer District (MSD), an American urban water quality analyzing agency, website.
“Nowadays, this stream-side ecology is massively impacted by escaped garden plants, as well as by high-nitrogen dog pee and poop, and the erosive influence of feet, paws and bike tires,” said Jones.
“As stream-side chemistry and ecology change, salmon and trout struggle to survive in creeks that were once perfectly suited to them.”
The water quality of the Lower Fraser River, which most Lower Mainland creeks and streams eventually drain into is rated as poor or marginal according to the Environment Canada website. This could be seen as an indicator to the health of these local ecosystems.
“Of all the influences, torrents of polluted storm water runoff are by far the biggest stress,” said Jones.
Garbage, whether discarded directly or indirectly, is also an issue in water habitats of all kinds.
“Garbage is one of the larger issues the local creeks face, it harms the fish, the creek bed, the water quality, and sadly it is one of the easiest issues to fix,” said Jones. “It’s simple human ignorance that causes this problem.”
“More than the chemical and physical detriments that garbage can and do pose to fish species, I feel it’s the idea behind the pollution of our fish habitats that is much, much more dangerous to fish populations as a whole,“ said Mark Nasu, a former SHaRP employee and a third year Environmental Engineering student at UNBC.
“It is the statement made by us allowing ourselves to dump this waste into our waters that is the single longest term danger to any fish population.”
The decline in urban fish populations is negative but not surprising based on the abuse urban streams and waterways are facing.
“I began volunteering on Cougar Creek in 2004. By that time, fish populations were already in very serious decline,” said Jones.
“Talking to people who have lived in North Delta since the 1960s or earlier, I’ve learned that fish populations were quite robust not that long ago in Cougar Creek.”
Although populations are in decline and Lower Mainland fish species are feeling the stress, Jones said. “I was pleasantly surprised to learn in Fall 2009 that Delta staff, prior to dredging the Westview sediment trap, had rescued well over 100 fish from the deep pool there. Salmon, trout, stickleback and even goldfish, nature is amazingly resilient.”