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Project Background:
A unique feature dominating the landscape of the
City of River Falls is the Kinnickinnic (Kinni) River, a Class I trout
stream that flows through the center of town. Recognizing the unique
character of the Kinnickinnic, River Falls has invested time and money
in the river corridor for the future enjoyment of fishing enthusiasts,
hikers, canoeists and kayakers. The river is one of the premier,
naturally sustaining trout fisheries in the Midwest, primarily producing
brown trout. The Kinni arises from a series of large springs three
miles north of Interstate 94, then flows southwesterly for 23 miles
before entering the St. Croix River. In the vicinity of River Falls,
the river is broad and shallow, averaging 40 feet wide and a foot deep.
Over the years, numerous projects have
been implemented to protect and improve the condition of the river. In
2002, the City adopted a new
Storm Water Management Ordinance, which is designed to protect the
Kinnickinnic River from the negative impacts of storm water runoff
associated with new development. The ordinance requires developers of
new homes and businesses to utilize best management practices (BMPs)
that infiltrate storm water runoff from rain events of 1.5 inches or
less. Examples of these infiltration BMPs are grass swales, rain
gardens, and large-development scale networks of ponds and infiltration
areas. In the pond network, a wet detention pond collects and holds the
storm water runoff and settles out pollutants such as suspended solids
and nutrients. The cleaner water from the wet pond is gradually
channeled to an infiltration area, where it percolates through the soil
to recharge the groundwater system.
The goal of the City of River Falls
Storm Water Management Ordinance
is to prevent degradation of the Kinnickinnic River due to the effects
of changes in storm water runoff caused by new development. Key
strategies that have been implemented to achieve this goal include:
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Controlling rates of storm water runoff from
developing and redeveloping areas as a
method of preventing downstream
flooding; |
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Controlling the amount of sediment and
associated pollutants contained in storm water
runoff from developing
and redeveloping areas; |
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Controlling the volume of storm water runoff
leaving developing and redeveloping areas
as a method of replicating
pre development hydrology. |
Successful implementation of these strategies should
result in the following desirable outcomes:
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No downstream flooding attributable to storm water
runoff from developing and redeveloping areas. |
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No detectible change in the thermal regime of the
Kinnickinnic River associated with storm water runoff from developing
and redeveloping areas. |
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No detectable increase in the amount of sediment
and associated pollutants attributable to storm water runoff from
developing and redeveloping areas. |
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No reduction in groundwater recharge attributable
to developing and redeveloping areas. |
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No detectable reduction in
the base flow of the Kinnickinnic River
associated with storm water runoff from developing and redeveloping
areas. |
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No detrimental change in the
Macroinvertebrate
community of the Kinnickinnic River associated with storm water runoff
from developing and redeveloping areas. |
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No reduction in the Trout populations of the
Kinnickinnic River associated with storm water runoff from developing
and redeveloping areas. |
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No detrimental change in Trout habitat in the
Kinnickinnic River associated with storm water runoff from developing
and redeveloping areas. |
Project Scope:
There has been
concern about how new development in River Falls may affect the
Kinnickinnic River by an increase in storm water runoff (water quantity)
and pollutants from lawns, cars, etc. (water quality). As the
Kinnickinnic River is one of the best coldwater streams in the state,
there is a great concern for maintaining the health and well-being of
the river’s aquatic community. In order to take an active role in
measuring the river's health and well being, the City has implemented a
monitoring program aimed at evaluating the effectiveness of the Storm
Water Management Ordinance for preventing degradation of the
Kinnickinnic River due to new City development.
The goals of the North Kinnickinnic
River Monitoring Project are to:
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Identify the present condition of
the Kinnickinnic River through a number of physical, chemical, and
biological monitoring measures;
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To continually monitor the river
during the build-out phase of new subdivisions such as Sterling Ponds;
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To continue to study the impact of
the increase in human population near the river after the developments
are completed and built out.
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To help support the monitoring project,
the City applied for a grant from the Wisconsin Department of Natural
Resources (WDNR). Since the City did not receive supplementary
WDNR funding for this project, the project scope has been limited to the
essential monitoring work that can be supported with City funding.
The current scope of work includes temperature monitoring, water quality
monitoring, base flow surveys, and monitoring of macroinvertebrates.
Temperature monitoring, water quality monitoring, and base flow surveys
will be conducted by City staff, while macroinvertebrate monitoring will
be conducted with assistance from the University of Wisconsin River
Falls.
The City has retained Short Elliott
Hendrickson (SEH) as a consultant to coordinate this monitoring
project. The annual results of each of the four key monitoring
components will be examined by SEH to determine if the new storm water
ordinance appears to be to be protecting the Kinnickinnic River as new
development occurs in the project area.
The North Kinnickinnic River Monitoring
Project began in the spring of 2004, and the 2004 monitoring results are
now available on the project website.
Precipitation:
A total of 19.82 inches
of precipitation was recorded in River Falls during the April-September
2004 period, compared to the normal total of 20.67 inches for this time
period. Rain fell on 55 days, or 30% of the April-September 2004
period.
The months of April,
June, July and August 2004 were drier than normal; whereas the months of
May and September were wetter than normal. Nearly 60% of the total
April-September rainfall occurred in May and September.
Infiltration:
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 The City of River Falls
Storm Water Management Ordinance, which requires infiltration of all
storm water runoff from rain events of 1.5 inch or less, would have
provided infiltration of 94% (18.58 inches) of the total rainfall (19.82
inches) that occurred during the April-September 2004 period.
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Storm water best management practices in place at
Sterling Ponds |
Kinnickinnic River Flow:
The flow of the
Kinnickinnic River is a reflection of precipitation and storm water
runoff from predominantly agricultural and urban land uses throughout
the 165-square mile Kinnickinnic River Watershed. The mean (average)
daily flow of the Kinnickinnic River at County Highway F during the
April-September 2004 period is presented in the figure below. Daily
rainfall, as measured in River Falls, is also presented in the figure
below.
Frequent rainfall in May
and early June 2004 resulted in a series of 5 substantial runoff events,
with peak flows ranging from 137-184 cubic feet per second (cfs). Drier
conditions and below-normal rainfall prevailed in June, July, and August
2004. However, a 1.47-inch rainfall on July 11 produced a significant
runoff event in mid-July, with a peak flow of 150 cfs. Back-to-back
2.44-inch and 1.80-inch rain events on September 14 and 15 produced the
largest runoff event of the year, with a peak flow of 235 cfs and a
7-day duration.
Please note: The USGS
Monitoring Station at County Road
F is very near the confluence of the Kinnickinnic River with the St. Croix
River.
The flow monitor is not within the monitoring area of this study.
However, the data does show the tie between storm water influences
(runoff events) and the
flow of the river through its entire system.
Temperature Monitoring:
The Thermal Impact
of Untreated Storm Water:
The thermal impacts of
untreated storm water discharges to segments of the Kinnickinnic River
within the City of River Falls, especially in the downtown and Glen Park
areas, have been clearly documented by temperature monitoring research
conducted by the local Kiap-TU-Wish Chapter of Trout Unlimited. These
thermal impacts are also evident in the South Fork of the Kinnickinnic
River. The Trout Unlimited temperature monitoring research can be
viewed at:
http://www.lambcom.net/kiaptuwish/stormwater/stormwater.html
Kinnickinnic River
Temperature Monitoring Results:
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 May-September 2004
(summer) temperature monitoring data were obtained for the Kinnickinnic
River at Sites 1, 1A, and
2. River temperatures at these three
monitoring sites averaged 13.8°C and ranged from 7.7-19.9°C over the
course of the summer. Near-normal river temperatures probably prevailed
in the North Kinnickinnic River Monitoring Project Area during the
summer of 2004, since the 2004 average summer air temperature of 18.7°C
(65.6°F) was only slightly lower than the normal average summer air
temperature of 19.2°C (66.5°F).
No storm water-related
thermal impacts were evident at Site 1, downstream from Sumner Creek and
Sterling Ponds, during the summer of 2004. |
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City of River Falls monitoring station at
Site 1 |
Upstream summer
temperatures at Sites 1A and 2 were nearly identical to downstream
summer temperatures at Site 1. A comparison of temperatures at Site 1A
(upstream) and Site 1 (downstream) is shown below.
The average monthly and
summer temperatures at Sites 1,
1A, and
2 were also nearly identical, as
shown below.
The summer 2004
temperature regime in the Kinnickinnic River at Sites
1, 1A, and 2 was
ideal for coldwater macroinvertebrate and
brown trout communities.
Approximately 95% of all temperatures recorded at Sites
1, 1A, and 2
during the May-September 2004 period were less than 17°C, which is the
top of the optimum temperature range for a healthy coldwater macroinvertebrate community. A temperature of 17°C is considered to be
the optimal temperature for brown trout survival. Greater than 99% of
all temperatures recorded at Sites 1,
1A, and
2 during the May-September
2004 period were less than 19°C, which is the top of the optimum
temperature range for brown trout growth. One hundred percent of all
temperatures recorded at Sites 1,
1A, and
2 during the May-September
2004 period were less than 20°C, which is the top of the optimum
temperature range for brown trout survival.
No thermal spikes were
apparent at Site 1 during seven significant rainfall and runoff events
in May, June, July, and September 2004. For example, in contrast to a
very distinct thermal spike at Division Street (a heavily impacted site
downstream of the monitoring area) during the September 5
rainfall event, no thermal spike was apparent at Site
1, downstream from
Sumner Creek and Sterling Ponds.
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 With limited development
in the Sterling Ponds subdivision in 2004, some of the Sterling Ponds
storm water management practices (wet detention ponds and erosion
control measures) in place, and with Sumner Creek providing a lengthy
buffer between the subdivision and the Kinnickinnic River, any Sterling
Ponds storm water impacts on the river were projected to be minimal in
2004. As such, the 2004 Kinnickinnic River temperature monitoring data
should serve as a useful baseline condition for evaluating the future
effectiveness of the City of River Falls Storm Water Management
Ordinance as development progresses at Sterling Ponds.
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A direct storm sewer discharge to the
Kinnickinnic River at Division Street |
Sumner Creek and
Sterling Ponds Temperature Monitoring Results
Accurate measurement of
Sumner Creek flow at Sites 4 and
6 and documentation of discharges from
the Sterling Ponds wet pond at Site 5 were not possible in 2004, using
temperature monitoring data alone. Nor was it possible to determine if
there were any discharges of storm water from the Sterling Ponds subdivision, with
any accompanying thermal impacts carried downstream to the Kinnickinnic River, via Sumner Creek. Adjustments to the temperature
monitoring scheme at Sites 4-6 will be made in 2005 to improve this
situation. An additional temperature monitoring site at the mouth of
Sumner Creek would also be very desirable.
Macroinvertebrate
Monitoring:
Information will be available soon
Fisheries Survey:
Information will be available soon
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