BOARD01914

• Board Meeting Date: 12/4/1974
• Description: Agenda or Table of Contents, Minutes, Resolution
• Board Meetings - Doc Type: Meeting

delineation for the intermediate regional flood will be designated by
the Water Conservation Board as a matter of course as the floodplains
are delineated. However, it will be sometime after that in the usual
course of events before the low hazard zones are delineated. In some
,cases, this might follow by a year or two or perhaps even more than
that, depending on the pressure to delineate the low hazard zone. With
that in mind, it would seem important to me that the regulation should I
state that when the low hazard zone has not yet been designated or
delineated, the entire floodplain ~ou1d be managed without reference to
the paragraph on exceptions. I would presume, Mr. Sparks, that you
probably intend that they be administered that way anyway, but it would
certainly help in the clarification and the understanding by the local
governmental entities if that was actually stated.

Relative to ad hoc decisions when one building permit comes up. which
is questionable, I think there is a tendency on the part of the local
governmental unit or the administrators to look at it from the stand-
point of what effect will that one building, or one fill. or one sub-
division. or one shopping center have on the floodplain. No matter
what your intent is, the tendency for the local legislative bodies
would be still to look at it in terms of that one imposition because it
is difficult to look down the road and assume that there will be many
other encroachments of a similar nature. I do feel that it would be
important to include at the end of. I had section 3 and I don't know if
the sections have changed, I had the end of section 3. paragraph 3.1(5).
This refers to the old draft and it may still be applicable for the
new draft. At the end of that paragraph (5), that the modification be
made. by changing the period at the end of the sentence to a comma and
adding the fOllowing words. ". assuming equal degree of encroachment on
both side of the stream with obstruction of similar character."

When defining the low hazard zones. I don't know if this would be appro-
priate to actually have in a regulation or in the guidelines to the
regulation. I think I would like to leave that up to staff interpretation
and recommendation. When defining the low hazard zone it is my opinion
that the low hazard zone should take into consideration the matter of
bridge plugging. particularly in urban areas. At our earlier meeting
of September we talked about the 1965 flood. We talked about the large
number of trailers which plugged tile bridges in the Denver area. My
feeling is that when defining the low hazard zone bridge pluggi~g. ,cif
fifty percent should be utilized in the hydrological determinations
when defining the depth and backwater impacts. What that amounts to is
realistically appraising the typical situation which exists in an
urban area during a flood period; namely. that the bridges do get
plugged. I believe that a fifty percent of plugging of the bridges
would be a reasonable value to use in those cases.

Mr.. Sparks.mentioned the survey taken at the Urban Drainage and Flood
Control District Seminar on floodplain management. As I recall, it
probably was split fifty-fifty down the middle relative to whether or
not the one foot or three feet would be satisfactory or not. There was
no poll taken of course on what appears in the regulation or the pro-
posed regulation at this time. One of the staff members was at the
seminar and he did point out that there was valid engineering and

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