YAVAPAI COUNTY, ARIZONA Federal Emergency ... - FEMA Region 9

The Verde Lakes Estates in the Town of Camp Verde experienced severe flooding
from West Clear Creek in September 1970, December 1971, October 1972,
February 1976, and February 1980 (Sellers, W.D., Hill, R.H., and Sanderson-
Raw, M., 1986; USACE, 1975; FEMA, 1985, Preliminary 1991). The peak
discharges are shown in Table 4. The 1980 flood was so severe that channel
alignment and grade were significantly altered. This alteration occurred after the
mapping used for the 1985 Flood Insurance Study was completed in 1978
(FEMA, 1985, Preliminary 1991).
Historic peak discharges at the USGS West Clear Creek gaging station, near the
Town of Camp Verde, are shown chronologically for the seven historic ranked
annual discharges in 23 years of record (see Table 4).
No significant flood-related losses, either in lives or property, have been recorded
since the Town of Chino Valley was founded in 1971. The heaviest rainfall of the
year usually occurs between July and September, but there are also secondary
storms that come in from the Pacific Coast during the later winter months. The
winter snows dissipate rapidly due to the dry air. Both thunderstorms and rapid
snowmelt conditions are potential flood problems. The Town of Chino Valley is
subject to hazards produced by rainfall in the nearby City of Prescott.
Historic records of major floodflow events in the Town of Clarkdale area indicate
that many of these flows have resulted in relatively little damage to property.
Historic floodflow events recorded on the Verde River are shown in Table 4. The
discharge values have return periods between 10- and 2-percent annual chance
events as determined from gage records (1916 through 1920 and 1966 through
1979) compiled by the USGS and subsequent log-Pearson Type III analysis. The
February 21, 1920, event is the maximum flood of record and has an estimated
recurrence interval of a 2-percent annual chance flood event. The February 7,
1980, flood event had a 20-year recurrence interval.
Historical records of major floodflow events in the City of Cottonwood area
indicate that many of these flows resulted in relatively little damage to property
and were mostly inconvenient in nature. The extensive development in the City of
Cottonwood which has occurred since these events increases the likelihood that
the resulting property damage would be much more significant. Significant
flooding problems have occurred as a result of high magnitude floodflows on Del
Monte Wash. This problem has occurred as a result of floodwaters breaking out of
the channel at the East Main Street crossing and flowing downstream on the
adjacent overbanks through the most highly developed portion of the City of
Cottonwood. This breakout resulted from insufficient culvert capacity beneath the
East Main Street crossing and from debris blockage of the culverts. On
August 26, 1964, a high intensity rainfall event occurred over the Del Monte
Wash drainage basin and resulted in a relatively large magnitude flood event. An
excerpt from the "Verde Independent" on September 3, 1964, stated, "...this storm
of August 26, alone dumped more than the 8-year average of 2.18 inches, falling
in a 2-hour period. The day before the big storm 0.88 inch was reported in
Cottonwood." The 2.18-inch rainfall in a 2-hour period translates to
18