I. Authorizing Resolution Passed by the Wastewater Utility’s Governing Board for the Sponsored
Project Application
This project is included in the City of Ames F2013-2018 Capital Improvements Plan (CIP) that was
authorized by the Ames City Council in Spring 2013. Enclosed with this application is the page from the
CIP that specifically address this project.
II. Letters of Support from Project Partners
The Iowa Department of Natural Resources has served as a partner on this project. Enclosed with this
application is a letter of support from Nate Hoogeveen, the River Program Coordinator.
III. Letter from the Wastewater Utility’s Bond Counsel Indicating Concurrence with the Sponsored
Project Concept
Dorsey & Whitney, LLP serves as bond counsel to the City of Ames. Enclosed with this application is a
letter of concurrence with the Sponsored Project concept.
IV. Assessment of the Impacted Waterbody and its Watershed with Data that Supports the
Identification of the Water Quality Problems to be Addressed.
Iowa DNR Provided a copy of a Flathead Catfish Study which shows that for the South Skunk River, the
13th
Street Dam in Ames, IA serves as an obstacle to passage. No Flathead Catfish have been sampled
upstream of the 13th
Street Dam since 1970. Sampling for other species of fish has shown similar results,
including only one Channel Catfish since 1970. The South Skunk River page from the Flathead Catfish
Study has been enclosed with this application.
V. Discussion of Project Goals and Objectives
In-stream Habitat Enhancements
The proposed modifications to the 13th
Street Dam will allow fish passage upstream to the Hannum’s
Mill Dam. The Hannum’s Mill Dam is the only dam upstream preventing fish passage to the entire South
Skunk River. The Oakland Mills Dam is 188 river miles below the 13th
Street Dam. Access to headwaters
on the Des Moines Lobe geological landform will be important for the fishery. The segments of river
immediately upstream of Ames contain cobble and rock substrates that are not available in many other
portions of the South Skunk River.
The existence of the dam likely limits the populations for certain species that would typically be in
place, such as deepwater overwintering ictalurids like channel catfish and flathead catfish. The period of
sampling record upstream of the 13th
Street Dam saw only a single channel catfish sample in 1970 with
30 subsequent years of records, and no flatheads during the same period. These would be the primary
species to benefit. Additional species that are present downstream, but not upstream of the 13th
St dam
include Bullhead Minnow, Channel Shiner, Emerald Shiner, Freshwater Drum, Longnose Gar, Shortnose
Gar, Shoal Chub, Slenderhead Darter, and Smallmouth Buffalo. Additionally, the Creek Heelsplitter and
Paper Pondshell species of mussels would also benefit from biological connectivity resulting from this
project.
Installation of Natural Channel Design Techniques
The proposed modifications to the 13th
Street Dam will use natural channel design techniques
including the strategic placement of weir boulders, base stone, and gradation stone to direct the flow as
well as pool water and protect the river bank. These natural channel design techniques will help protect
the river bottom and river banks during periods of high flow by reducing the concentration of kinetic
energy immediately downstream of the dam. The highest velocities will also be directed away from the
sides of the river and will be slowed downstream of the dam by installation of a j-hook configuration of
natural stone.
VI. Evaluation of Alternatives Considering the Unique Demographic, Topographic, Hydrologic, and
Institutional Characteristics of the Planning Area
Project Alternatives
Many alternatives were considered since the inception of this project. Public meetings were held to
receive stakeholder input and develop a design that accommodated those needs. The one constraint
from the beginning was that the 13th
Street dam cannot be removed altogether. The reason the dam
was originally built was to provide groundwater recharge to the aquifer serving the City of Ames
drinking water wells. During periods of drought, the dam has proven invaluable at mitigating the effects
on the groundwater supply to the City of Ames.
With removal of the 13th
Street Dam eliminated as an alternative, the stakeholder needs were taken
into account. The arched rock rapids design with weir boulders, base stone, and gradation stone was
chosen because it used natural channel design techniques and it provide the greatest in-stream habitat
enhancements to fish and mussels in the South Skunk River. The current design also will provide
recreational opportunities for canoeing and naturalist groups, as well as eliminate the dangerous
hydraulic circulation that has caused so many deaths throughout Iowa in recent years.
In approximately the past two years, the project has become more expensive due to required
hydrological modeling and increased materials costs. While determining whether to continue with the
project, the City of Ames met with Nathan Young at the Iowa Institute for Hydraulic Research in Summer
of 2012, to discuss alternative designs. It was determined at that time that, excluding dam removal,
there are no lower-cost design alternatives that could be pursued that would provide the in-stream
habitat enhancements, natural channel design techniques, as well as meet the other needs of the
stakeholders.
VII. Description of Practices to be Implemented with the Expected Water Quality Outcomes
The Iowa Department of Natural Resources – River Programs has worked closely with the City of Ames
to develop a design based on the principles outlined in various publications by Luther Aadland on the
topic of Natural Channel Design. Enclosed with this application is documentation on the design for the
project.
VIII. Discussion of project locations, land ownership, and any plans for acquiring properties or
easements
The project is located in North River Valley Park upstream of 13th
Street. The property is owned by the
City of Ames and, due to its design footprint, no acquisition of property will be needed for this project.
Figure 1 – Aerial of Low-Head Dam in City of Ames at North River Valley Park.
Figure 2 - View of Low-Head Dam in City of Ames at North River Valley Park, looking north.
IX. Identification of Any Other Organizations or Resources to be Involved in the Project and their
Expected Contributions
Other organizations that have been involved with this project include the Skunk River Paddlers, the
Hawkeye Fly Fishing Association, and individual citizens. Verbal commitments of funding have been
made to this project, from some individuals and groups, but no money has actually been donated at this
time.
X. Proposed Project Schedule with Major Milestones
Project Event/Milestone Date
Application for Sponsored Projects Funding Submitted July 19, 2013
Public Hearing November 14, 2013
Public Comments Closed November 21, 2013
Commission Meeting & Approval December 17, 2013
Complete Hydraulic Modeling January 2014
Begin Construction June 2014
Complete Construction September 2014
XI. Proposed Evaluation Procedures and Measures
Biological and Physical Monitoring Data
Several decades of fish population and community samples exist for sites upstream and downstream
along the South Skunk River. Iowa DNR has indicated in past grant proposals that Channel Catfish and
Flathead Catfish populations could be targeted for increased sampling in the future after modifications
to this dam have been completed. This could also include tagged releases downstream of the 13th
Street
Dam. Monitoring for tagged releases downstream would provide verification that the proposed
modifications were successful.
30
LOW-HEAD DAM MODIFICATIONS PROJECT STATUS: Scope Change Delayed
Cost Change City of Ames, Iowa Capital Improvements Plan
DESCRIPTION/JUSTIFICATION
This project will modify the low-head dam in North River Valley Park. The primary purpose is to reduce the risk of drowning due to a hydraulic recirculation downstream of the dam. Additional benefits of the improvements include increasing the recreational opportunities for paddlers and kayakers, and creating an opportunity for fish to migrate upstream past the dam.
COMMENTS
The low-head dam in River Valley Park serves an essential function during periods of sustained drought by pooling water in the primary recharge zone for the Water Plant�s Downtown Well Field. This type of dam has the potential to create a dangerous hydraulic recirculation downstream of the dam. The recirculation can trap a person below the surface and can lead to drowning in just a few feet of water. A conceptual proposal has been developed jointly between the City of Ames and the Iowa Department of Natural Resources that will achieve the primary goal of improved safety, while also providing additional recreational opportunities for paddlers and kayakers. The design would also facilitate the movement of fish upstream past the dam, helping to increase the upstream fish population diversity.
The project was originally shown in the FY 10/11 CIP at an estimated cost of $150,000. The City received a grant award of $75,000 from the state�s Low-Head Dam Public Hazard Grant program. Over the past two years, staff has been unsuccessful in receiving permit clearance for the original design concept. Work with the Iowa Department of Natural Resources and the Iowa Institute for Hydraulic Research has resulted in a design that should be able to receive permits from the necessary agencies but at a higher cost estimate of $225,000. Staff is pursuing additional grant opportunities to help absorb the cost increase, although an additional $25,000 has been added to the Water Fund�s contribution compared to the FY 12/13 CIP carryover. Should the City be unsuccessful in securing the additional grant funds, Council would need to decide whether to pursue the project by allocating additional local funds. Construction is now anticipated in fall 2013, but will be highly dependent on river levels.
LOCATION
North River Valley Park, E 13th Street � Map 6, location O-9
FISCAL YEAR PRIORITY 3TOTAL 2013/14 2014/15 2015/16 2016/17 2017/18
COST:
Construction 225,000 225,000
TOTAL 225,000 225,000
FINANCING:
Water Utility Fund 75,000 75,000Low-Head Dam Public Hazard Grant 75,000 75,000Other Grant Funding 50,000 50,000In-Kind Donations 25,000 25,000
TOTAL 225,000 225,000
PROGRAM - ACTIVITY: DEPARTMENT: ACCOUNT NO.
Utilities � Water Water & Pollution Control 510-3938-489
884
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879
881
0 80 16040 Feet
0000000
2402424024
282828282828282828280000028
20202000200
89
0000000000000000000 4040404040404040404040404040 87887
2424242400024282828282828000028282800
00000
8080808080808080808080808080808080808080
16161600160160160160
40404040404040404040
879
242424242424240002424242424242424242400240242424242424000240240240240
28280280280878878
20202020000200200200200
20202000000878878878
00878161600160878878
876
876
8080808080808080
000404040
16161600160 2020202020
877877
87787780808080808080808080
878
878
879
87879
880
880
0000000 4040404040404040404040
8080808080
880
880
000878160160878878
876
878
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880
ST232
882.2
WEIR E
ST205
882.2’
ST175
882.3
WEIR D
ST136
882.4
WEIR C
ST85’
882.5
WEIR B
ST -3’
882.7
WEIR A
ST163
882.3’
ST125
882.4
ST72
882.5’
ST -3
882.7’
~24 randomly
spaced
boulders (3’ to
6’ dia)ST292
884’, J-HOOK;
exact station
may be
adjusted after
weirs A-E are
constructed;
structure
mostly
submerged
ST270; 877’;
J-HOOK tip
(3-5’ boulders,
2 rows, 1 as
footer)
Materials notes
1) Weir boulders/randomly spaced boulders can range from
3’-6’ diameter (70% ≥ 3’ diameter, 20% ≥4’, 5% ≥5’)
2) Flat slab boulders on near bank may need to be limestone
quarry run. Speci#c weight of 1.5 or greater is preferred.
Variations in thickness (1’) can be accomodated by varying
size of materials below.
3) Filter (.1’ to .5’ mix of gravels and cobble; enough gravels
may be excavated from streambed for footers, but .2 to .6’
stone of ~10 percent volume or tonnage of base stone will
be needed.)
$at slab boulders
along bank as
walking surface,
~1’ x ~4’ x ~4’,
grouted, double
as anchor
boulders for weirs
(i.e., use elevations
listed for ends)
Stair steps,
dimensions to
be designed
by City
880.5’x
880.5’x
881x
881x879.7’x
879.7’’x
880.2x
xST54880.2
878.9’x
879.4’
x
x
x878.9’
879.4’
878.6’
878.1’
xx
xx
878.1’878.6’
x
x
x
x881.5
881.3
880.2
879
x
xxx881.5 881.3
880.2879
Placement notes
1) Trough .5’ lower than neighboring stones for both base
material and weirs. Weir A does not have an abrupt trough
due to the already constricted cross section.
2) Nested weirs should have a parabolic shape both in the
plan view and in elevation. This is di&cult to display in a cross
section because the arches are 3-dimensional. Looking at the
weir A cross section should help clarify ... the weir should
drop in elevation most rapidly from the banks and $atten out
near the edges of the trough. Spot elevations (yellow x)
should also help clarify.
2) Footer stones are shown at the edges, and for the j-hook.
At the edges, these will be necessary to brace weir stones at
the cabled concrete. Place downstream & at lower elev.
3) Weir stones must be carefully placed to interlock, and
brace from upstream to downstream for maximum stability.
Weir A stones will brace on dam. and some base/#ll will be
hand-placed.
x 881
x 881x 880
x 881x882.3
x882.3
x881.7
x881.7
x881.3
x881.4x881.5
x881.5
Plan view, 13th Street Dam Hazard
Mitigation recommendations
ed
xx
.2x
WEI
ST8
s to
ed
.2880.2
xxx
879879.7’
ST85’
882.5
ST 90 Cross
Section (dashed)
105
Skunk River (Figure 7) - There are multiple recent and historic collections of various size classes
of flathead catfish from the Skunk River and South Skunk River between its confluence with the
Mississippi River and the 13th
Street Dam (< 4 ft. tall) in Ames. The Oakland Mills Dam (9 ft.
tall) near Mt. Pleasant is the only dam in this section of river that is a barrier to upstream fish
movement. Although this dam is listed as 9 ft. tall, the effective height of the structure is much
lower and it is not believed to be a barrier to upstream fish passage during high flows (Vance
Polton, Iowa DNR, personal communication). There are also several recent and historic
collections of multiple size classes of flathead catfish from the North Skunk River between its
confluence with the Skunk River and the Wagaman Mill Dam (10 ft.). Several recent collections
have also documented multiple sizes classes of flathead catfish in Cedar Creek and Big Creek.
The presence of individual flathead catfish has been documented by recent samples in Middle
Creek (tributary of North Skunk River), and Indian Creek (tributary of South Skunk River. There
is evidence of flathead catfish populations in the South Skunk River downstream of Ames, the
North Skunk River downstream of the Wagaman Mill Dam, the entire Skunk River, Big Creek,
and Cedar Creek.
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#Oakland Mills Dam
Wagaman Mill Dam
Rock Creek Lake Dam
Ames 13th Street Dam
3rd
U
%
#
1970 - 1989
pre 1970
³
1990 - 2009
S
Dams > 4’
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# All sample sites
Flathead catf ish population present
Flathead catf ish individuals present
Watershed
4th
5th
6th
Sites where f lathead catf ish were sampled
Stream order