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Issues Facing Urban Streams
One of our most neglected resources. Miles and miles have been piped underground. Those above ground have become overrun with invasive species. Pass City of Portland buried streams map.
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How has the watershed changed?
“Children of a culture born in a water-rich environment, we have never really learned how important water is to us. We understand it, but we do not respect it.” William Ashworth Diking (riverbank, mudflats, side channel habitat) Draining (wetlands and roads) Dredging (and straighten, removal of woody debris) Damming (including roads and culverts) Logging, Mining, Ranching Trapping Wildlife- Beavers Building Paving Historically, glaciers carved the rivers, forests grew in the rich deposits left behind, wetlands and estuaries and rivers supported a rich natural environment, with beavers, salmon. As a nation, we saw the potential to create an environment that we could manage, one which would provide us with economic returns and a comfortable lifestyle. What all this comes down to basically is control. Humans want water where they want it and when they want it. For this reason we have channelized streams, cut down trees, dammed rivers all to build and maintain our farms and cities. From the Wetlands Conservancy website it seems as though about 98.5% of wetlands in Oregon have been drained (1.4 million acres left out of a previous 86 million). In the Willamette Valley alone, more than 500 acres of wetlands are lost per year.
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River Control: Between 1880 and 1950, 13 dams were constructed along Willamette tributaries. 96 miles of riverbank were hardened with riprap, and 69,000 snags were removed. We’ve tried to control floods and harness rivers for power… Once settlers had built permanent structures along the Willamette, they didn’t want them to go anywhere- and therefore didn’t want flooding or other nature movement of the river. Between 1880 and 1950, US Army Corps Of Engineers constructed 13 major dams on Willamette tributaries. They reported that “snags and drift piles” from fallen trees in the river (aka, large wood we discussed earlier as a benefit) were a hazard to boats, and removed 69,000 snags from channels and riparian zones. The Corps also hardened 96 miles of Willamette riverbank with riprap, closed side channels, and redirected all water to the center of the channel.
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Deforestation: By 1895 in Oregon, over ½ of the hardwood forests and woodlands had been converted to agriculture. Almost all riparian conifer forests were gone. We’ve stripped the land of its resources
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Development: Cities were formed as the population grew, especially along rivers and river junctions.
We’ve created huge cities of impervious surfaces and buried streams…
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This is a similar image to the last pictures
This is a similar image to the last pictures. The black in this picture shows development. The red line is the urban growth boundary and the green is forest cover.
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Just 30 years later the image has changed drastically
Just 30 years later the image has changed drastically. I like to go back and forth between these two images a couple of times because this is a very powerful image.
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Water Quality Industry, agriculture, cities, other sources
1,400 miles of streams in basin violate water quality standards. Willamette River violates temperature, bacteria and mercury water quality standards. Superfund sites, skeletal deformities in fish.
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Trees cut 17-34% of solar radiation
Important because most aquatic organisms are cold blooded which means their body temp is the same as the water they live in. Their metobolic rates are controlled by temp, there is a range where they are most efficient. The higher the temp the faster the metabolic reactions occur – there’s an optimum level and a lethal limit.
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These two diagrams show just what is happening as we urbanize an area
These two diagrams show just what is happening as we urbanize an area. This picture shows a natural functioning forest. A water budget is basically a graph of where the water is going when it enters a system. You should point out here how small the amount of runoff is – this show how most of the water that enters the system is staying within the system. Evaporation will lead to more precipitation and the cycle will continue.
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When we remove vegetation we alter the system
When we remove vegetation we alter the system. This shows an unhealthy cycle. Too much runoff, not enough groundwater recharge. 1. In winter with heavy rains, what will happen to water in the stream? What will this cause? In summer, when stream relies on groundwater for it’s flows, what will happen? What will this cause? But the question is not whether to develop – we are here and we have needs – it is then HOW to develop. We can sustainably live on the land. We just need to understand the land first so that we know how to relate to it.
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SOLVE Riparian Restoration
Scientifically-based watershed restoration Long-term monitoring and maintenance Community involvement Education and outreach Partnerships are key Goal of sustainability: people and projects SOLV’s focuses on the restoration philosophy we just talked about. Team Up bases it’s work on the best science available and works from the watershed approach. We take on a site for 8 years, the first of these years focuses on active restoration. During these years we remove invasive species, plant native trees and shrubs, do any in stream work that might need to be done on a site, mitigate for rodents and other creatures that might harm new plantings and monitor and maintain the site. The next years focus on monitoring and maintenance. We do photo point and vegetation monitoring and have crews and volunteers complete maintenance work on the sites such as mulching, caging, weeding and watering. We always focus on the community and partnerships. Team Up works because of all the partners involved. We work with local governments, churches, schools, watershed councils, friends groups and any other groups or individuals in the community that are interested in working with us. We work to foster these relationships to make them stronger ensuring that the work that we start will not be left unattended in the future. We focus on community ownership to foster that sense of stewardship. Once the community becomes an active part of a project we know that that project will be sustainable in the future.
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Watershed Restoration
Restoration of a watershed returns the ecosystem to as close an approximation as possible of its state prior to a specific incident or period of deterioration. Remove invasive plants Plant native trees and shrubs Stabilize banks near streams Add large wood to streams Monitor and maintain sites
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Impacts of Invasive Species
Create monocultures Cause erosion Do not shade creek Ruin habitat The invasive in the photo is garlic mustard which is a newer invasive to the Portland Metro area. It is allelopathic meaning it excretes a toxin from its roots which kills other herbaceous plants from the forest floor. Note the invasives root structures of common invasive people plant in their yards to comparable natives!
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