Wednesday, March 13, 2013

Montana Fly FIshing Report and Rip-Rap

   Here's latest fly fishing report from here in Missoula, Montana.
Bitterroot River: Yeah, there are a few skwalas out. You will see more boats than bugs. The water is very low (buy your gel coat stuff in bulk)  and most of the fish are still lurking around their winter lies. They will eat a dry but it's spotty and you better make sure you present it right. No sloppy=more fishy! Since most of the fishermen out right now are guides waiting to work, that shouldn't be too tough. Should it?
  To say the fishing is good would be inaccurate. It ain't bad. Let's leave it at that.
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                                                       STEVENSVILLE PROJECT

Ever wonder why the Bitterroot seems to be getting filled in with gravel more and more? Is getting a 3-10 permit as simple as it seems? In the Bitterroot Valley, I would say YES! The project below Stevensville is only the latest in a long list of recent "stabilization" projects. If a guy builds a structure in the floodplain/floodway, he should assume responsibility for his actions!  Have a look at this if you want to know a little more about what's happening. Maybe it's time to question this practice in the Bitterroot Valley.

Read the whole thing here: http://www.mtaudubon.org/issues/wetlands/documents/Go_With_Flow.pdf

Learning to Go with the Flow
Streams and Bank Stabilization Spring 2002
One of the key ways that people impact Montana’s rivers and streams is by stabilizing their banks—more and more weirs, riprap, barbs, and other structures are lining our riverbanks. This publication is a quick guide to the most common bank stabilization structures being used in Montana. It describes what the structures look like, how they work, and lists their possible impacts on natural stream processes. Finally, it offers a series of practical actions that can help to preserve and, in some cases, improve the health of Montana’s precious waterways.
Streams and Rivers Need Room to Move
In order to understand how bank stabilization structures impact our rivers and streams, it is important to know the basics about how streams function. They are dynamic systems that are meant to flood—and they must have room to move. Stream corridors are a com- plex network of water, land, plants, and animals.
Many rivers and streams found in Montana’s val- leys and plains meander, sweeping and snaking across the landscape. If given space, the bends in meandering streams naturally and slowly migrate. This meandering tends to create a pattern in which outside bends are dominated by cut banks (caused by erosion), and inside bends are dominated by gravel bars (where sediment is deposited). This process, in combination with the moist, often wet soils and high water table found next to streams, creates a corridor called a riparian area.
A river’s floodplain is often defined by riparian veg- etation, which is adapted to growing in this dynamic system. Plants associated with riparian areas include cottonwoods, willows, dogwood, alder, sedges, forbs, and cattails. Healthy, functioning floodplains, with their full complex of riparian vegetation, serve many useful purposes, including:
• Reducing flood heights by soaking up, storing, and slowly releasing floodwaters; • Decreasing stream velocities and soil erosion; • Improving water quality by filtering and reduc- ing nutrients, pesticides, salts, sediments, organic wastes, and other pollutants running into our streams and, ultimately, our drinking water; and
• Providing the most diverse fish and wildlife habi- tat found in Montana.
Riprap, Rootwads, Revetments, and More
When someone buys a piece of land, they usually expect their property line to stay in the same place it was
Streams and Bank Stabilization 1on the day the land was purchased. If the piece of land is located on a stream or river, this principle does not work—because streams and rivers are dynamic: banks erode and material is deposited elsewhere, new chan- nels are cut, and old channels dry up. Although erosion is natural, erosion levels can be accelerated above natural rates because of human-caused activities, such as removal of riparian vegetation, bank stabilization, or upstream manipulation of stream channels. Increasingly, land- owners are turning to bank stabilization in an attempt to control streams to protect their property from both natural and human-caused erosion. Measures used to sta- bilize banks are generally classified into three categories: armor, channel structures, and vegetative methods.
Armor comes in two forms: bank armor and levees. Bank armor is a blanket of resistant material that is placed along the streambank, extending into the stream. Riprap is a common form of bank armor. When water hits the hard surface of riprap, the water cannot scour the riverbank, thus erosion is reduced. Levees are structures composed of rock or fill material constructed within the floodplain. They constrict and concentrate the erosive force of flood flows.
Channel structures are walls built into the active channel of a stream. Their purpose is to steer the fast- est portion of a stream’s current away from the eroding bank. Barbs, jetties, vanes, and weirs are in this category. These structures are sometimes favored over bank armor because they use less rock, can be less disruptive to natu- ral stream functions and riparian habitat, and can allow a stream to use more of its floodplain. Though channel structures can be less damaging than bank armor, they can contribute to a more serious problem because of the cumulative effects of channelization, discussed below.
Vegetative methods generally involve tree trunks fixed into banks at angles so that they redirect the swift- est portion of a stream’s current away from the bank. They also stabilize banks. Rootwads, tree revetments, and live vegetation are included in this category. Although rootwads and tree revetments are “softer” than riprap or channel structures, they fundamentally do the same thing: disrupt natural stream functions to reduce ero- sion of banks. Planting native riparian vegetation is the measure most in harmony with the natural functions of a stream.
The number, location, spacing, angle, size, and height of all of these structures vary, depending on the stream type and conditions, the landowner, and the consultant/engineer involved. The most common mate- rial used for bank armor and channel structures is large rock. In addition, gabions (defined below), concrete, logs, and (rarely) sand bags are used. Broken concrete is discouraged because it often contains toxic paint, petro- leum products, rebar, and similar contaminants that are illegal to place in Montana’s streams and rivers. In the past, car bodies and tires were used.
One Thing Leads to Another
Landowners use barbs, riprap, and other struc- tures to prevent rivers and streams from using their floodplains and changing their courses. While this may sound reasonable and harmless, the consequences for our rivers can be serious. While a few barbs or a short stretch of riprap will not significantly impact a stream, ten barbs in a row can turn a river to hit the opposite bank, a long stretch of riprap can cause serious erosion downstream, and the combination of many projects can cause channelization.
Currently there is increasing public attention focused on the way government agencies are allowing more and more bank structures to armor our river- banks. In 2000, a study done in Billings on the Yellow- stone River concluded that bank stabilization structures now cover 41% of the 30-mile research area, double the amount found in 1957. A similar study performed in 1998 on the Yellowstone River in Park County (Liv- ingston area), found that 21% or 22.2 miles of this portion of the river was lined by bank stabilization structures.
As more bank stabilization structures are built, both short-term and long-term consequences arise. In the short-term, stabilization measures tend to physi- cally stabilize one local stretch of riverbank or divert flows away from one bank to another. This can trigger increases in river flow velocities, exacerbate down- stream bank erosion, and lead to further instabilities downstream. In other words, preventing natural ero- sion at one location can significantly increase erosion downstream of the project. Therefore the “problem” is neither controlled nor solved, but merely relocated from one spot to another, negatively impacting down- stream landowners. Increased downstream erosion often causes affected landowners to put in structures to protect their property—and the cycle repeats itself over and over again.
Over the long-term, bank stabilization can cause the channelization of our rivers and streams as flood- plains narrow or disappear, natural stream migration is prevented, and, ultimately, riparian vegetation does not regenerate. Channelization also impacts the health of rivers and streams by: exacerbating the severity, duration, and frequency of local flooding events and erosion downstream; preventing the maintenance and formation of sandbars and backwater areas; and degrading critical fish and other habitat required in aquatic systems. At a time when government agencies and the private sector are spending billions of dollars each year to address these issues, it seems “a penny wise and a pound foolish” to eliminate the natural features that provide these same services at practically no cost.

Sounds great.

http://www.mtaudubon.org/issues/wetlands/documents/Go_With_Flow.pdf

www.flyfishmissoula.com


2 comments:

  1. What an outright abortion that Poker Joe Stabilization Project is. Six Hundred Feet! of sterile rock wall for our fishing pleasure - Thanks Ravalli County Flood Plain Coordinator! That's a bang up job you're doing.
    Good to know we have top men working on our side. Top. Men.

    Fun fishing with you, as always, Pred. Maybe next time we can use your bugs?

    ReplyDelete
  2. So caustic, and yet so right. Break-off king, OUT!

    ReplyDelete