solar- powered screen protects fish in yellowstone national park
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ASSOCIATION OF CONSERVATION ENGINEERS Page 1 2000 Proceedings
SOLAR- POWERED SCREEN PROTECTS FISH
IN YELLOWSTONE NATIONAL PARK
James J. Strong1 Daniel L. Mahoney2
ABSTRACT
1 President, Aquadyne, Inc. P.O. Box 189 Healdsburg, CA 95448
2 Fishery Biologist, Yellowstone National Park, WY 82190
Reese Creek, the northernmost tributary of the Yellowstone River, located in Yellowstone
National Park, is the only stream in the park system that has had water diverted from it for
private irrigation purposes. As such, various stretches of Reese Creek have been subjected to
dewatering. With these exceptions, however, Reese Creek fisheries habitat has been rated as of
moderately high quality. Major dewatering of Reese Creek coincided with the spawning
migration of various species of fish such as : cutthroat trout, rainbow trout, brown trout, brook
trout, and mottled sculpin. As a result of dewatering, successful incubation, hatching, emergence
from gravel, and fry to the Yellowstone River appeared to be negligible at one point. Since there
are only a limited number of spawning tributaries in the upper Yellowstone River, the National
Park Service in 1991 embarked on a program to improve conditions on Reese Creek that were
detrimental to fisheries habitat. At that time, three concrete diversion structures on Reese Creek
were constructed to replace three wood and metal structures that were no longer functioning
properly. Also included was the installation of government furnished metal work which included
self-powered, self-cleaning overshot type fish screens, slide gates on each concrete structure, and
two parshall measuring flumes with concrete wingwalls located above and below the diversion
structure. Because the hydraulic characteristics of the concrete structure did not allow for the
necessary eight-inch head loss available to operate the overshot screens, the screens never did
operate properly. In 1999, the National Park Service retrofitted the overshot screens to enable
them to function by means of solar power. Results after one year of operation are presented.
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INTRODUCTION
In 1997, the National Geographic magazine chose the Yellowstone River as “The Last Best
River” in the United States. Flowing freely for 670 miles, the Yellowstone River is the longest
river in the lower-48 states without a single dam. First made famous by Lewis and Clark’s Corps
of Discovery for its spectacular scenery, abundant wildlife, and thriving fish populations, the
Yellowstone River sadly last year also joined the American Rivers list of “Most Endangered
Rivers”.
The threat comes as landowners, downriver from Yellowstone National Park (YNP), have sought
to prevent natural seasonal flooding through environmentally detrimental “bank stabilization”
techniques, including “rip-rap” lining the stream with huge piles of boulders. Not only does bank
stabilization alter the Yellowstone River’s natural course and increase flow velocities, it also
changes the function of the river by not allowing it to reach the floodplain and serve as a natural
seed spreader and habitat protector for native fish, such as cutthroat trout, and other riparian-
dependent species.
Other threats to the Yellowstone River come in the form of agricultural withdrawals from various
tributaries which limit the reproductive success of resident and salmonid populations. About
twelve tributaries of the Yellowstone River between YNP and Livingston, Montana are used by
salmonids for spawning. In 1932 the northern boundary of YNP was expanded to include the
entire Reese Creek drainage. The purchase of the land, however, did not include the water rights
to Reese Creek or its tributaries. Reese Creek is the northernmost tributary of the Yellowstone
River within the YNP border, and is the only stream within YNP in which water is removed by
private landowners for irrigation purposes which continues to this day.
DISCUSSION
In 1984, YNP initiated studies to monitor stream discharge and fish distribution in order
ASSOCIATION OF CONSERVATION ENGINEERS Page 3 2000 Proceedings
to assess the effects of irrigation and complete dewatering on the aquatic resources of Reese
Creek. Both resident and adfluvial populations of salmonids use Reese Creek during the year. It
was suspected that water-taking limited the spawning success of these populations by allowing
fry to move into the diversion ditches and become cut-off from the stream’s main stem, isolating
them in small pools, and stranding trout redds when the creek is completely dewatered. Later
studies have described the physical habitat of Reese Creek, magnitude and duration of the
Yellowstone cutthroat trout ( Oncorhynchus clarki bouvieri ) spawning run, and population
characteristics of the resident cutthroat trout population. Results from these studies indicated
that without adequate streamflow, spawning success of salmonids moving from the Yellowstone
River into Reese Creek and subsequent fry survival would be severely reduced.
Reese Creek has been routinely dewatered completely below the very first diversion. On
several occasions minimum flow recommendations were made. In 1991, an agreement was
reached stipulating minimum flows of 0.037 cubic meters per second (cumecs) (1.31 cubic feet
per second-cfs) during the spawning season, depending upon the discharge upstream from the
diversions being at least 0.079 cumecs (2.79 cfs). For the other six months of the year, the
available discharge would be 50% of whatever was available.
In fall of 1991 the old diversion structures were removed and replaced with adjustable V-
notched fish ladders, irrigation ditch headgates, and cylindrical self-cleaning fish screens. These
screens, however, did not function properly because of insufficient available head and became
clogged with debris. Normal operation of a rotating self-powered, self-cleaning overshot fish
screen relies on the passage of water through an intake divider which directs flow to turbine-type
vanes on both sides of the screen drum. The screen is then rotated operating on the principal that
water flow plus head equals power. Debris is carried over the screen and washed downstream.
The rotating drum turns approximately 14 times per minute when installed with the proper
amount of head.
As mentioned previously, the hydraulic characteristics of the concrete structure erected in
1991, when the screens were originally installed, did not allow for the head loss required to
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operate the overshot screens properly. In 1992, there was one incident of complete dewatering
reported. To remedy this situation, the two overshot screens at two separate diversions on Reese
Creek were retrofitted to solar power operation utilizing photovoltaic cells to create electricity
directly from sunlight. Photovoltaic modules generate direct current (DC) when exposed to
sunlight or other sources of light. The photovoltaic modules along Reese Creek were placed
during installation to a fixed position to approximate the ideal point when facing the sun in order
to generate maximum power
In 1999 the National Park Service reinitiated monitoring of Reese Creek. Project
objectives included:
1) install and monitor the effectiveness of retrofitted solar powered self-cleaning fish screens,
2) monitor fish use and fry emergence, and 3) determine effectiveness of fish passageways.
Study Area.
Reese Creek originates at Cache Lake and flows approximately 11.5 km (7.15 m) to its
mouth at the Yellowstone River. Electric Peak and Sepulcher Mountain respectively form the
western and eastern boundaries of the drainage basin. Downstream of the third diversion riparian
vegetation consists of cottonwood (Populus spp), Rocky Mountain juniper (Juniperus
scopulorum), sagebrush (Artemesia spp), rose (Rosa spp), and willow (Salix spp).
Three irrigation diversions are located in the lower reaches of the stream at 0.8, 1.6, and
2.0 Km (0.5, 1.0, and 1.5 m) upstream from the mouth of Reese Creek. The diversions are
referred to as the first, second, and third diversion, respectively. Fish passageways are located at
the first and second diversions. A cylindrical, galvanized steel culvert is located under the
Stephens Creek Road. Staff gauges and parshall flumes have been installed in two locations; one
downstream of the first diversion, and the other approximately 200 m (660 ft) upstream of the
third diversion (Figure 1). Differences in discharge at the two sites have been used to estimate
the amount of water being taken from the stream.
ASSOCIATION OF CONSERVATION ENGINEERS Page 5 2000 Proceedings
Fish species that occur in Reese Creek include Yellowstone cutthroat trout, rainbow trout
(Oncorhynchus myskiss), brown trout (Salmo trutta), brook trout (Salvelinus fontinalis), mottled
sculpin (Cottus bairdi), and mountain whitefish (Prosopium williamsoni). Yellowstone cutthroat
trout/rainbow trout hybrids are also found in Reese Creek. Upstream of the third diversion to the
confluence with Electric Creek, Reese Creek may contain a resident population of salmonids.
Electrophorectic analysis of 22 specimens tested in 1990 indicated that the 16 individuals were
pure Yellowstone cutthroat trout, while the other six showed signs of hybridization with rainbow
trout. From Electric Creek upstream to the stream’s source at Cache Lake appears to be fishless.
Several potential barriers are found throughout this stretch of water (Varley 1976). Cache Lake
is also reported to be fishless despite stocking 14,000 brook stout, and 300,000 Yellowstone
cutthroat trout between 1912 and 1929 (Varley 1981).
Methods.
The Reese Creek study area was divided into six reaches extending upstream from the
mouth at the Yellowstone River to the third diversion. From the mouth upstream to the first
diversion was divided into sections one, two, and three. The area between the first and second
diversion was divided into sections four and five. Section six was established between the
second to the third diversion (Figure 1). Diversion ditches were sampled separately from the
main stem of the stream. Data were recorded under DI, DII, and DIII for the diversion ditches.
Electrofishing was used to sample fish from 21 May to 14 October 1999. Captured fish were
visually identified to species, measured (total length mm), weighed (g), and when possible
identified to sex and stage of maturity. Trout containing meristic characteristics of both
Yellowstone cutthroat trout and rainbow trout were considered hybrids. Fish were given a
section specific clip to monitor movement throughout the creek. All trout that were ripe or
nearly ripe were counted as spawners. All salmonids > 80 mm (3.15 in) in total length that were
unable to be identified as to species were counted as fry.
Fish screens were installed in all three diversions on 14 July 1999. Solar- powered, self-
cleaning, rotating fish screens were installed in diversions two and three (Figures 2 and 3), and a
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non-rotating screen that needed to be manually cleaned was installed in diversion one. Solar
panels were mounted on large poles and wired to a deep cycle battery to supply it with a constant
charge; the battery was wired to a small motor that rotated the screens. Due to the small size of
diversion one, and the surrounding tree cover, the manual screen was selected over a solar-
powered, self-cleaning screen.
Results.
Five species of fish, as well as cutthroat/rainbow trout hybrids were collected in Reese
Creek during electrofishing surveys. Cutthroat/rainbow trout hybrids were the most abundant
fish captured (42%), followed by mottled sculpin (28%), brown trout (13%), rainbow trout
(12%), Yellowstone cutthroat trout (3%), and brook trout (2%). Unidentified trout fry were also
collected during the sampling season (Table 1). Fish were captured in highest numbers below
the first diversion (16.76 fish/ 100m) and lowest between the first and second diversions (5.97
fish/ 100m). Between the second and third diversion fish were captured at a rate of 11.25 fish/
100m.
Spawning Yellowstone cutthroat trout, rainbow trout, and cutthroat/rainbow hybrids were
captured from 21 May to 23 July 1999. Sampling of the stream did not take place from 23 July
until 13 August, and no spawning fish were captured in later sampling efforts, indicating the
spawning had ceased sometime between these two dates. Spawning cutthroat, rainbow, and
hybrids were captured in all study sections. Trout fry were most abundant on 20 August, which
correlated with peak water temperature (Figure 4). Young of the year and adult brook trout were
captured in the early part of the sampling season as far upstream as the third diversion. No
spawning brown trout or brown trout fry were captured during surveys.
Shocking of the first and third diversion after the installation of fish screens produced
only one fish. An unidentified trout fry was captured in the first diversion following the
installation of the retrofitted fish screens. No fish were captured in the third diversion.
Diversion two was dry throughout the sampling season. Clipped fish were captured both above
and below the section in which they were marked.
ASSOCIATION OF CONSERVATION ENGINEERS Page 7 2000 Proceedings
CONCLUSION
Installation of fish screens has prevented the migration of fry into the diversion ditches.
Only one fry was captured in the first diversion after the installation of the fish screen. It is
possible that this fish entered the area between the screen and the diversion headgate while the
screen was removed for cleaning. No trout were collected in the third diversion.
Fish passageways appeared to work as planned. Clipped fish were found both upstream
and downstream from the section in which they were clipped. Sculpin, however, were absent
above a small cascade located at the end of section one, suggesting that they were unable to
maneuver over the cascade. (Figure 5). One trout was collected in the first diversion ditch after
installation of the new screens. Preventing Reese Creek from being completely dewatered has
had positive effects on the fish population in the stream. An increase in the number of spawning
fish and distribution of size classes indicates that Yellowstone cutthroat trout, rainbow trout,
brook trout and cutthroat/rainbow hybrids have been spawning successfully in Reese Creek for
several years (Table 2). Declining numbers of fry captured in the lower sections of the stream as
the season progressed suggests that fry do not spend a significant amount of time in Reese Creek
and quickly disperse downstream into the Yellowstone River. The area above the second
diversion was not sampled on enough occasions to determine fry use and dispersion in this area.
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