FLOOD08407

• County: Jefferson
• County: Adams
• Community: Arvada, Westminster
• Stream Name: Little Dry Creek
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 4/1/1979
• Prepared For: Jefferson County / Adams County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Mr. Ben Urbonas, P.E.
Page Two
May 8, 1978

Drainage law also generally follows the concept that nature
should be allowed to take its own course, and the natural water-
courses developed over the years are the best way to carry off
surface waters. In Hankins vs. Borland, 163 Colo. 575, 431 P.2d
1007, 1010 (1967), the Colorado Supreme Court stated:

"Natural drainage conditions may be
altered by an upper proprietor pro-
vided the water is not sent down in
a manner or quantity to do more harm
than formerly."

The reverse is also true. The builder of an "improvement" to the
natural watercourse cannot build such an improvement so as to
obstruct the natural passage of the water. Further, once a govern-
ment has involved itself in the construction of drainage and flood
control improvements, it must see that such improvements are main-
tained.

Finally, on a general note, the least that can be accomplished
by local government is to identify and then regulate the use of the
flood plain. So long as good engineering practices are followed,
a local goverment should not, be liable because a particular parcel
of land was not identified as being in the flood plain.

I. General.

In reviewing the alternatives discussed in the engi-
neer's report and finally the recommended alternatives, I have
based my opinions on the legal theory that an alternative is legally
acceptable if it does not increase damage from its present level in
time, space or amount upstream, downstream, or adjacent to the pro-
posed improvement. Of course, each alternative was looked at and
legally evaluated individually and in conjunction with the other
alternatives in the other reaches covered in the engineer's report.
Therefore, if any alternative or any recommended alternative viewed
in conjunction with other alternatives proposed to be constructed
increases damage from its present level in time, space or amount
upstream, downstream, or adjacent to the proposed improvements, then
that alternative shall be considered legally unacceptable.

Finally, when the final design for this project is completed,
the engineer should address himself to the sequence of implementation

Mr. Ben Urbonas, P.E.
Page Three
May 8, 1978

of the recommended alternatives so that any increased damage
upstream, downstream, or adjacent to the improvements as a re-
sult of the s~quence. of implementation of the selected alterna-
tives can be avoided.

II. This portion of the opinion will proceed from the
"uphill" portion of the basin area of Little Dry Creek drainage-
way and comments will be made on all ten reaches of the drainage-
way.

a) Reach 5. Since achieving flow separation of storm
and irrigation waters is a policy of the District, the engineer
should be requested to address that policy in regard to the
Farmers Highline Canal. Also, the engineer should be requested
to address the problem and any suggested alternatives, if necessary,
of the "minor darns for stock watering or irrigation that have been
constructed across the channel." Page 11-1. Has the recommended
plan been formulated based on these dams being in place, and does
their removal or failure adversely affect downstream areas?

b) Reach 4. Is the present channel adequate for con-
veyance of the 100-year flood for fully developed conditions or
for present conditions? If it is capable of conveying the 100-year
flood from present conditions, the participating entities may de-
sire further information as to the necessity for alternations, if
any, to the channel for it to adequately convey the 100-year flood
from future conditions.

c) Reaches A 1 D and A 1 C.
sufficient based on 10-year capacity
year capacity in A 1 C.

d) Reach A 1 B. The relocation of the channel to the
east side of the Colorado and Southern Railroad is a recommenda-
tion that would expose the governmental entity in which this
improvement is located to needless potential legal liability if
the improvement fails to work properly as designed, if damages
have been shifted by reason of this relocation to an area which
has not previously experienced damages or if increased damages
to an area are experienced by reason of this improvement. Poten-
tial legal liability is created by this recommendation because
it shifts drainage from the historic channel (see general com-
ments above).

Recommendation is legally
in Reach A 1 D and 100-