Stream
Mappers are the investigative sleuths of the Malibu Creek Watershed.
Their responsibility is to get acquainted with the watershed in order
to locate degraded habitats and pollution sources.
Stream
Mappers look for the for the following:
Discharge
points and outfalls
Discharge
points and outfalls are pipes and culverts that carry storm water runoff
into a stream at a single point. As a result, water quality and stream
morphology may be impacted, especially at the point of discharge into
the creek. Not all discharges are legal. Current information regarding
the location of all outfalls to the creeks is limited. This information
will help Heal the Bay update available mapped information.
Unstable
streambanks
Unstable
streambanks are a common problem along local streams, particularly ones
that are subject to upstream development. Banks that are eroding or collapsing
into the stream do not have stable soils for vegetation to establish.
Eroding banks contribute sediments that can impact the habitat of steelhead
trout and macroinvertebrates, and collapsing banks can block stream flows,
causing flooding and damage to nearby property.
Artificial
streambank modifications
Artificial streambank modifications often are used in urbanized or developing
watersheds to prevent flooding. This method of streambank stabilization
and flood control eliminates the natural vegetation. Vegetation provides
food and habitat for aquatic and land based birds and wildlife, slows
the flow of surface runoff, and balances the nutrient levels of streams.
This alteration is often necessary when private property backs up to a
stream and allows structures to be built close to the stream's edge. While
artificial bank modification may solve the problem of one property owner,
the results are a funneling of problems further downstream to the next
property owner, and beyond.
Impacting
land uses
Impacting land uses that are adjacent to streams can potentially affect
the stream environment. The land uses of interest are those that have
replaced riparian vegetation. For example, some places in the watershed
have horses or other animals that graze right at the edge of the streambank.
In other locations shopping centers or houses may be located right on
the streambank edge. While these land uses may not have a discharge directly
to the stream, runoff from these areas could have an impact on stream
health.
Large
patches of exotic and/or invasive vegetation
Large patches of exotic and/or invasive vegetation are plants introduced
from other parts of the country or other regions in the world. Many of
these plants are well adapted to local climate and soil conditions. Some
are aggressive and may out-compete and displace native vegetation. Problems
arise when these plants do not provide the food and habitat required by
the native species of birds and wildlife.
Possible
barriers to fish passage
Possible
barriers to fish passage potentially affect the passage of steelhead trout
and other fish to protective spawning grounds within the upper watershed.
Currently, the annual steelhead run is restricted to the lowest 2.5-mile
stretch of Malibu Creek, below Rindge Dam. Healthy fish habitat is usually
productive habitat for many other aquatic species.
Illegal
dump sites
Illegal
Dump Sites exist partially because dumping is cheaper than legal disposal
of waste. Frequently dumped wastes include hazardous chemicals, or large
items like appliances. The problem is compounded when certain areas become
recognized as places to dispose of waste. Areas in and around streams
are frequently used as dump sites because they are off the beaten track,
lessening the likelihood of being caught in the act. These areas will
likely be near roads.
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