MYTH #1: The October, 1983 flood
was the 100-year flood for every wash in Tucson and Pima County.
FACT: The Santa Cruz River, Rillito Creek and Brawley
Wash reached near 100-year flood levels. Most small washes experienced relatively
minor flooding during 1983.
MYTH #2: Since we recently had a 100-year
flood, we will be safe from flooding for another 100 years.
FACT: Floods have no memory of
the past and 100-year floods can occur in consecutive years. For example,
the Salt River in the Phoenix metropolitan area experienced 100-year floods
in three consecutive years in 1978, 1979 and 1980. Floods that are smaller
or larger than the 100-year flood can also cause major damages.
MYTH #3: If your
house or property was not flooded in the 1983 or the 1993 flood, then it
is not in the floodplain and you don't need to be concerned about flooding.
FACT: Most washes in Pima County, particularly the
smaller washes, did not experience major flooding during the 1983 or 1993
events. Large scale flooding events don't necessarily serve as good indicators
of whether a house or property may be in the floodplain or whether it is
subject to flooding.
MYTH #4: If I locate my home outside
the floodplain I will never have any flood damages.
FACT: Not necessarily true! Erosion along desert washes
can be extensive. A watercourse can migrate and move closer to a building.
Also, floods larger than the regulatory 100-year flood can occur.
MYTH #5: If it is not raining in my
neighborhood, then the wash I'm next to will not flow.
FACT: Flash floods can move miles downstream and inundate
areas that didn't receive rain. On July 26, 1981, seven people died when
a flash flood hit unexpectedly at Tanque Verde Falls.
MYTH #6: Placing branches along the
embankment of a wash is an effective method of flood protection.
FACT: Larger flows will move buoyant materials downstream
where they collect and almost always worsen flood damages.
MYTH #7: If a roadway dip section looks
like it only has six or eight inches of water running over it, then it is
safe to drive across.
FACT: This is false... but it's one of the hardest
lessons to learn. You can see that there's water in the roadway dip section...
BUT...the pavement underneath the water may have eroded or completely washed
away. If the pavement is no longer there, the wash crossing could be several
feet deep or more and be extremely hazardous.
MYTH #8: I can make any drainage improvement
I need to on my own private land as long as the flow enters and leaves my
property at the same location.
FACT: All drainage improvements involving a regulatory
floodplain require a permit. Numerous drainage problems and drainage violations
are caused as a result of inadequate or inappropriate drainage improvements.
