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Why was the Dam Unique? conducted in June and July 2017. The results of the survey
are summarized in the table below.

The Quaker Mill Dam exhibited several features that were It was found that, as of July 2017, only three other extant
unusual. These include the hollow construction with interior dams in Iowa had large concrete fishways. A fourth fishway,
chambers; the monumental concrete fishway; and the sin- located on the Iowa River Power Company Dam in Johnson
gle Tainter gate with manually operated hoist. No compre- County, was smaller and narrower than the others, so it did
hensive surveys of dams in Iowa have been conducted that not qualify as a monumental fishway, but it was the only oth-
identify the number of dams in the state that exhibit each of er intact fishway observed during the field survey. All of the
these features, but the combination was unusual, and pos- fishways for which a type could be determined were of the
sibly unique in the state. To demonstrate the distinctiveness Swazy type.
of the Quaker Mill Dam, an attempt was made to identify all
extant dams in Iowa with similar features. Dams with hollow Tainter gates were found to be slightly more common than
construction cannot be identified readily based on their ex- concrete fishways on Iowa dams. Seven extant dams were
terior appearance, so the investigation was limited to dams found that exhibit this feature, although all have multiple
with large concrete fishways and Tainter gates. The num- gates rather than the single gate on the Quaker Mill Dam.
ber of dams with hollow construction is not known, but only Only two—the Iowa Falls Dam and Lakehurst Dam—are
one other dam in Iowa—the Mitchell Mill Dam built in 1925 similar to the Quaker Mill Dam in that they feature both a
in Mitchell, Mitchell County—is described in the records of concrete fishway and one or more Tainter gates. The Mar-
Iowa’s State Historic Preservation Office as having hollow ket Street Dam in Ottumwa has a total of nine Tainter gates,
construction like the Quaker Mill Dam. 27 including one separated from the others on the north side
of the powerhouse, as well as one bascule gate. In all cas-
The table below lists all extant dams in Iowa known to re- es, the Tainter gates are powered by electricity rather than
tain a concrete fishway or Tainter gate as of July 2017. The manually powered. The majority employ moveable hoists on
list is based on a comprehensive survey of lowhead dams rails, although two dams—Rutland Dam and Market Street
in Iowa compiled by the Iowa Department of Natural Re- Dam in Ottumwa—appear to have one stationary hoist per
sources (DNR) in 2010. Dams included in the DNR list that gate. Another dam that formerly had Tainter gates—the Fort
28
were sufficiently large to be comparable to the Quaker Mill Dodge Hydro Dam in Fort Dodge, Webster County—report-
Dam were investigated further through aerial photographs edly had a backup manual hoist. The Tainter gates and
30
and street-level photographs available online to determine hoists from the Fort Dodge dam have been removed since
which were known or likely to have either a large concrete the time it was recorded. The Quaker Mill Dam therefore ap-
fishway or floodgate. As a result of this survey, a total of 24 pears to have been unique in Iowa both for its small number
29
dams were identified as likely to have features comparable to of Tainter gates (one rather than multiple) and for its use of
the Quaker Mill Dam. On-site visits to 23 of these dams were an exclusively hand-powered hoist.

Iowa Dams Sharing Notable Features with

Quaker Mill Dam

Name River Location County Feature(s)
Center Street Dam Cedar River Cedar Falls Black Hawk 4 Tainter gates
Independence Mill Dam Wapsipinicon River Independence Buchanan large concrete fishway
Iowa Falls Dam Iowa River Iowa Falls Hardin large concrete fishway;
(southeast side) 3 Tainter gates
Iowa River Power Company Dam Iowa River Coralville Johnson small concrete fishway
Lakehurst Dam Maquoketa River Maquoketa Jackson large concrete fishway;
(1 mile west) 6 Tainter gates
Market Street Dam Des Moines River Ottumwa Wapello 9 Tainter gates
Mitchell Mill Dam Cedar River Mitchell Mitchell 2 Tainter gates
Red Rock Reservoir Dam Des Moines River Pella Marion 5 Tainter gates
(1.5 miles southwest)
Rutland Dam [West Fork] Des Rutland Humboldt 2 Tainter gates
Moines River

12 University of Iowa Office of the State Archaeologist