Log No. 97-R3-ELFO-2

January 8, 1997

Mr. J. Mark Robinson

Director, Division of Project

Compliance and Administration

888 First Street, NE

Washington, DC 20426

Dear Mr. Robinson:

The U.S. Fish and Wildlife Service (Service) has reviewed the July 2,
1996 \"Biological Assessment of the Spillway Rehabilitation Project at
Tippy Dam, Manistee Co., Michigan\" prepared by Dr. Allen Kurta. The
proposed action is to repair or rehabilitate the spillway at Tippy Dam,
on the Manistee River, for safety reasons. The biological assessment
(BA) and your August 20, 1996 letter requesting formal consultation in
accordance with section 7 of the Endangered Species Act of 1973 (Act),
as amended, (16 U.S.C. 1531 et seq.) were received on August 23, 1996.
This document represents the Service\'s biological opinion on the
effects of that action on the federally endangered Indiana bat (*Myotis
sodalis*). The Service concurs with the Federal Energy Regulatory
Commissions (FERC) determination that no other federally listed species
are likely to be adversely affected by the proposed action.

This biological opinion is based on information provided in the BA,
additional information provided by Consumers Power Company (CPCO), Dr.
Allen Kurta, the Indiana Bat Recovery Plan, and other Service files. A
complete administrative record of this consultation is on file in the
Service\'s East Lansing Field Office.

**CONSULTATION HISTORY**

Since Indiana bats were identified in the hollow spillway of Tippy Dam
(project \# 2580) in December of 1993, informal consultation has
occurred between the Service and the FERC or its designate (CPCO), on
several occasions. Consultation on the proposed action began when CPCO
briefed Mr. Kevin Stubbs of the Service\'s East Lansing Field Office on
the proposed spillway project during meetings on September 28-29, 1995.

CPCO via an October 13, 1995 letter to FERC, proposed to act as FERC\'s
designate and authority to prepare the BA for consultation with the
Service on the spillway project. FERC approved CPCO\'s request to act as
their designate in a November 28, 1995 letter and requested a copy of a
draft BA to review before final approval.

The Service commented on the Indiana Bat Management Plan (within the
Manistee River Land Management Plan) in a December 13, 1995 letter to
CPCO (and copied to FERC) and stated the Service\'s position that formal
consultation would be required for the proposed spillway project.

CPCO contracted Dr. Allen Kurta to prepare the BA and a draft BA was
sent to FERC on July 8, 1996. In a August 20, 1996 letter to the
Service, FERC requested formal consultation in accordance with section 7
of the Endangered Species Act of 1973 (Act), as amended, (16 U.S.C. 1531
et seq.) and enclosed a copy of the approved BA. The letter and BA were
received at the East Lansing Field Office on August 23, 1996.

The Service requested and received some additional information from CPCO
and Dr. Kurta via a conference call on September 17, 1996. The Service
notified FERC with a letter dated September 17, 1996, that the request
for formal consultation was accepted. A draft biological opinion (dated
November 13, 1996) with a cover letter was sent to FERC on November 14,
1996. CPCO provided comments back to the Service in a letter dated
December 5, 1996. Comments from Dr. Allen Kurta, primary author of the
BA, were included in CPCO\'s comments. The FERC responded with a letter
dated December 17, 1996, notifying the Service that the draft biological
opinion had been reviewed, but no comments were provided. All of the
comments received were considered in finalizing this biological opinion.

**BIOLOGICAL OPINION**

**DESCRIPTION OF THE PROPOSED ACTION**

Overview

The project primarily entails 1) structural rehabilitation of the
concrete spillway and concrete elements of the powerhouse tailrace, 2)
possible addition of ballast to the spillway interior to enhance
long‑term sliding stability, and 3) construction of a temporary
cofferdam, including any necessary auxiliary structures to operate and
maintain the spill capacity of the plant, during the rehabilitation
period.

Background

A comprehensive investigation was performed in 1993 to evaluate the
structural condition of all hydroelectric plants owned by CPCO,
including Tippy Dam. The investigation at Tippy Dam revealed extensive
deterioration of exposed concrete, resulting from freeze‑thaw cycles.
The damage posed no immediate threat, but repairs were deemed necessary
to extend the useful life of the dam. Consequently, after consulting
with the Federal Energy Regulatory Commission, Tippy Dam was scheduled
for spillway rehabilitation in 1997.

General Procedures

The most heavily damaged structures, such as supporting piers and upper
portions of retaining walls, will be replaced, whereas other concrete
components will be subject to surface repair. Surface repair consists of
removing any delaminated concrete by conventional methods and then
removing deteriorated concrete by hydraulic demolition, a procedure
which minimizes microcracking of the sound concrete that remains in
place. The rehabilitated spillway will conform to the original, shape,
dimensions, and elevations, and all engineering will meet the
requirements of the FERC Engineering Guidelines for the Evaluation of
Hydropower Projects. Rehabilitation activities will be typical of
large‑scale, civil/structural, concrete construction, with heavy
construction equipment staged around the spillway, including cranes,
barges, demolition equipment, concrete pumps, and earthmoving equipment.

Outline of Major Rehabilitation Activities

1\. Retaining walls at north and south ends (the Right Abutment and
Powerhouse Retaining walls): Resurface. The remainder of the unused fish
ladder, behind the north wall, will be removed.

2\. Supporting piers: Remove and replace.

3\. Vertical ogee walls underneath sills and intermediate walls:
Resurface.

4\. Log chute: The wall separating the log chute from the tumble bay
will be resurfaced, and the log chute floor (slab) will be repaired. The
sliding gate at the head of the log chute and its supporting structures
will be replaced by a concrete wall.

5\. Weir: Resurface.

6\. Tainter gates and tainter gate sills: New gates will be designed,
installed and tested. Tainter gate sills will be replaced. The tainter
gate sills form the highest portion of the ceiling of the middle eight,
internal chambers of the spillway. Replacement of the sills may entail
temporarily exposing the interior of the spillway and result in a
partial new ceiling for those chambers.

7\. Internal structures: Repair, as required. Such repairs will be
minimal and likely restricted to covering exposed rebar and grouting
cracks and/or joints in the upper portion of the spillway.

8\. Deck: Replace with new concrete deck.

9\. Electrical: Relocate a distribution line and install power for gate
hoisting, lighting on spillway deck, embedded heating elements, gate
heat lamps, deicing agitators, convenience outlets, and temporary power
for cofferdam slide gate.

Related Activities

1\. Cofferdam: A temporary cofferdam will be built upstream of the
present spillway and will consist of a structural steel framework with a
sheet pile overlay. Construction will include necessary auxiliary
structures, spill mechanisms, and modifications of the existing
structure for anchorage. Such modifications will include cutting and
installing pockets in the right (north) concrete abutment wall and log
chute pier for placement of structural steel beams (wales) that will
span the length of the spillway, upstream of the piers. In addition, the
cofferdam is expected to be anchored to the upstream, sloping face of
the spillway with 75‑100 concrete anchors that would be installed using
a rotary impact hammer. At the end of the project, after installation
and successful testing of the new spill gates, the cofferdam sheet piles
will be cut away with a torch and removed, but the anchors will be left
in place.

2\. Ballast: Ballast may be required to offset the weight of old
concrete that is removed as rehabilitation proceeds. Such ballast would
be placed inside the main spillway structure and would become a
permanent part of the structure, enhancing long‑term sliding stability,
as required by FERC Engineering Guidelines for the Evaluation of
Hydropower Projects. This ballast most likely would be in the form of
fill sand, approximately 5‑10 feet deep, that would be placed onto the
floor of the internal portion of the spillway. A concrete cap may be
added to prevent the sand from washing out. Ballast and the concrete cap
would be placed so as not to block any ventilation opening. Ballast will
not be added to the log chute chamber.

Seasonal Scheduling

Rehabilitation work will begin with construction of the cofferdam
starting on 5 May 1997. Dewatering the area between the cofferdam and
spillway and demolition activities will be delayed until 24 May or
later, after more than 99% of the bats have left for the summer (FERC
1996). Testing of the new spill gates, removal of the cofferdam, and
site restoration are scheduled for completion by 12 September 1997,
before most bats have returned for the upcoming hibernation season. The
ending date of 12 September

is necessarily subject to weather‑related delays. A tentative
construction schedule, indicating approximate durations for major
activities, is shown in Figure 11, but a detailed construction schedule
will not be known until a contractor\'s bid is accepted early in 1997.
The 5 May, 24 May, and 12 September dates, mentioned above, will be
specified in the request for bids.

Daily Scheduling

To finish the project by 12 September will require multiple work shifts
per day. Work may occur around the clock from 24 May to 15 August, when
bat use of the spillway is minimal. To minimize any disturbance to
hibernating or swarming bats, work will be restricted to daylight hours
prior to 24 May and after 15 August.

Summary of Procedures Adopted to Minimize Potential Effects on the
Indiana Bat

Construction design and scheduling have been modified, whenever
possible, to minimize or eliminate potential effects. Such modifications
are summarized below.

1\. The start of construction will be delayed until 5 May when most
bats, perhaps two‑thirds, have already left hibernation (FERC 1996).

2\. All other construction activities (dewatering the area between the
cofferdam and the spillway, testing of cofferdam spill procedures, the
addition of ballast, internal repairs, etc.) will be delayed until after
24 May, when virtually all bats have left hibernation (FERC 1996).

3\. The scheduled completion date of 12 September occurs before 85% of
the bats have returned (FERC 1996).

4\. If needed, ballast will be positioned in such a way that the lower
ventilation openings (bat access points) remain permanently open.
Ballast will be placed so that it does not interfere with flight near
these openings or make access any more difficult for the bats. Ballast
will be arranged so that it does not impair airflow, which might change
the microclimate inside the spillway (Richter et al., 1993).

5\. During internal repairs, surfaces and \"form holes\" used by bats
for roosting will be left unmodified, whenever possible. New concrete
added during internal repairs or replacement of the tainter gate sills
will be left in a slightly roughened state to facilitate roosting by
bats (Hall, 1962).

6\. No permanent modifications will be made to the ventilation holes or
to the grated opening into the log‑chute chamber that would limit their
use by the bats or interfere with the natural flow of air into and out
of the spillway. The grated opening into the log‑chute chamber will be
altered by removing every other bar to allow bats to freely fly through
the openings.

7\. The contractors will be instructed to keep all openings free of
obstructions (e.g., equipment or debris) between dusk and dawn,
beginning 1 August, so that the bats may continue to have nocturnal
access during the swarming season. Nighttime work from 1 to 15 August
will be restricted to areas away from the spillway and the log chute
entrance, if possible, to minimize disturbance to bats that do arrive
early in the swarming season.

8\. Testing the new spill gates will be done between one and two hours
after sunset on a night with no rain and preferably with external air
temperatures above 101 C (501 F), to minimize the number of torpid bats
actually in the spillway during testing.

Additional Protection or Recovery Actions

Overview

Tippy Dam is on the edge of the Indiana bat\'s range, and it is not
likely that substantial summer populations, if any, exist in the
surrounding area (Kurta, 1982; Kurta et al., 1989). Consequently, there
is little that CPCO can do to attract Indiana bats to Tippy Dam. There
are, however, things that can be done to make it more likely that any
bat that does find the dam can successfully use the spillway structure.

CPCO, therefore, will attempt to provide a more suitable environment for
swarming and hibernating bats, including Indiana bats. To that end, CPCO
will 1) monitor environmental parameters following rehabilitation and
attempt to modify the microclimate, if necessary, and 2) create roosting
cavities inside the spillway if interior concrete repairs are required.
In addition, CPCO will establish an educational display, for use by the
general public, near the dam.

Monitor Environmental Parameters and Possibly Adjust the Microclimate

Following rehabilitation of the spillway structure, CPCO will document
daily and seasonal changes in temperature and relative humidity inside
the spillway and make comparisons with pre‑rehabilitation data. Changes
in internal air temperature are not anticipated, because the dam\'s
dimensions and configuration will not change. Nevertheless, if internal
air temperature consistently falls below 01 C or consistently rises
above 8 1C during mid‑hibernation (December through February), then CPCO
will consider modifying the ventilation openings in the spillway, to
manipulate internal temperature conditions; such modifications might
entail permanent or seasonal closure of some or all lower openings to
retain cool air, or perhaps closure of upper openings to retain warm
air. A decrease in relative humidity is possible, and if it consistently
falls below 85% during mid‑hibernation, then CPCO will consider ways to
increase moisture levels within the spillway, such as allowing some
water to again flow down the walls. Poorly thought‑out modifications
that lead to changes in the microclimate may actually destroy the dam\'s
ability to act as a hibernaculum (Humphrey, 1978; Richter et al., 1993),
so any such manipulation will be done only after careful consideration
and consultation with the resource agencies and biologists experienced
with bats.

Provide New Roosting Cavities

Many bats roost inside solution cavities in the ceilings of caves, where
warmth or moisture may be more easily trapped (Barbour and Davis, 1969).
The form holes lining the internal walls of the spillway are heavily
used by the bats and presumably act in a similar manner. Consequently,
CPCO will incorporate new roosting cavities into the ceiling, and
possibly the walls, of the spillway if interior concrete repairs are
required. It is not presently known if interior concrete repairs will be
required. By varying the volume and location of the cavities, and
perhaps the material from which the cavity is formed (e.g., wood vs.
concrete), CPCO could provide a potentially valuable experiment in
creating artificial roosting habitat for bats. The designing and
positioning of the cavities would be done in conjunction with the
resource agencies and qualified biologists familiar with bats.

Provide an Educational Display for the General Public

CPCO recognizes that misconceptions and a lack of understanding the
importance of bats on the part of the general public, are a threat to
the continued existence of any bat species. Therefore, CPCO will
establish an educational display, for use by the general public, near
the dam. This would possibly include photographs, general information on
bats, and specific information concerning the importance of Tippy Dam to
the Michigan bat fauna. The display might be erected at the parking
areas frequented by fisherman, at the nearby campground run by the
Michigan Department of Natural Resources (MDNR), or some other
appropriate site.

**STATUS OF THE SPECIES**

Life History

The Indiana bat (Myotis sodalis) is a small 6‑10 gram bat that ranges
across much of the eastern United States. This species hibernates for
6‑8 months, primarily in abandoned mines and natural caves, where
ambient temperatures are typically 4‑6 1C and relative humidities are
usually greater than 85% (Hall, 1962). Although hibernating populations
are found in many eastern states, major ones occur only in the karst
regions of Missouri, Kentucky, and Indiana (Barbour and Davis, 1969;
Thomson, 1982; USFWS, 1983). Major hibernacula contain up to 100,000
Indiana bats, and at one time, more than 90% of the known population
hibernated in just three caves and one mine. In the 1960s and early
1970s, the species underwent a dramatic decline, primarily caused by
disturbance to hibernating populations and human alteration of
hibernation sites (Richter et al., 1993). The apparent lack of suitable
hibernacula and severe declines in the size of wintering populations led
to the Indiana bat being placed on the federal list of endangered
species (Humphrey, 1978; Lera and Fortune, 1979).

During warm‑weather months, male Indiana bats generally are solitary,
roosting in trees or perhaps caves on occasion (Hall, 1962). Female
Indiana bats, in contrast, gather in small colonies of less than 100
adults, to give birth and raise their single young. In summer, the
females typically roost underneath the loose bark of dead trees, but
cavities or the bark of living trees are sometimes used (Gardner et al.,
1991; Humphrey et al., 1977; Kurta and Caryl, 1995; Kurta et al., 1993,
in press). Roost trees are often located in riparian forest with
low‑to‑moderate subcanopy, although upland areas may be used as well.
These insectivorous bats forage primarily in and about the forest canopy
(Gardner et al., 1991; LaVal et al., 1977; Romme et al., 1995).

Like many hibernating species, Indiana bats participate in swarming
behavior during late summer and early autumn (Cope and Humphrey, 1977;
LaVal and LaVal, 1980). At this time of year, if one enters a cave
during the day, few bats are seen; however, at night, hundreds or even
thousands of bats may visit a cave, appearing to fly in and out the
entrance in a large, continual swarm. Swarming likely aids young bats in
finding appropriate hibernation sites, and during September, mating
occurs during these nocturnal visits to the caves (Fenton, 1969).
Although a few Indiana bats may roost in caves during the swarming
season, most Indiana bats probably roost in trees, as in summer.

The Indiana Bat in Michigan

Prior to 1993, biologists believed that Indiana bats spent only the
summer in Michigan, and ranged only as far north as Lansing, Ingham Co.
Based on recoveries of bats originally banded while swarming or
hibernating, biologists thought that the Indiana bats that spent the
summer in Michigan migrated to Kentucky for the winter (Kurta, 1980).
The recent discovery of a small number of Indiana bats hibernating and
swarming at Tippy Dam (Kurta and Teramino, 1994; Kurta, 1995b) extended
the known range of this species almost 200 km northward in the Midwest.

In northern areas, cavelike environments are generally too cold for bats
in summer, and most prefer to roost in places that are more easily
warmed by the sun. Tippy Dam is no exception, and very few bats, of any
species, use the spillway as a dayroost in June, July, and August (FERC
1996). To date, no Indiana bats have been found in the spillway during
these months, although the presence of this endangered species can not
be ruled out.

Tippy Dam is a swarming site, and hundreds of bats visit the spillway
each night, between dusk and dawn, during late summer and early autumn.
This is indicated by all‑night trapping over four nights, in August and
September 1995, that yielded approximately 2,700 bats. Most were little
brown and northern bats, but one individual, 0.04% of the total capture,
was an Indiana bat (Kurta, 1995b).

The Indiana bat became endangered due to natural events and human
actions. Sometimes their winter hibernacula are flooded, ceilings of the
hibernacula collapse, or cold temperatures kill the bats through
hypothermia. The most serious cause of decline had been human
disturbance of wintering bats by cavers, researchers, or vandals.
Reasons for the continued declines are unknown, however, but appear to
be associated with factors occurring during the nonwinter months, as
most of the known major hibernacula are protected. Permanent loss of
summer habitat, timber management practices, and pesticides may be
associated with the declines. Tree removal, either for harvest or land
clearing, has been the most direct, known threat to Indiana bat summer
roosts. Destruction or alteration of forest habitat could have serious
impacts on Indiana bat populations. Any harvest method that removes
standing, dead trees that are potential Indiana bat roosts could be
harmful.

**ENVIRONMENTAL BASELINE**

Approximately 20,000 bats, belonging to four species, hibernate inside
the hollow spillway of Tippy Dam. The spillway shelters the third
largest population of hibernating bats in Michigan, and it is the only
known bat hibernaculum in the Lower Peninsula of Michigan (Kurta and
Teramino, 1994; Kurta, 1995a, 1996). Most bats that hibernate in the
spillway are little brown bats (M. lucifugus) and northern bats (M.
septentrionalis), but a few eastern pipistrelles (Pipistrellus
subflavus) and Indiana bats are present. The exact number of Indiana
bats that hibernate in the spillway is unknown, because the internal
geometry of the dam makes it impossible to view closely, and thus
identify, every bat to species. The total number of Indiana bats is
estimated to range from only 3 to perhaps 65 bats, with the actual
number most likely on the lower end of this range (Kurta, 1995b). Both
male and female Indiana bats have been identified at Tippy Dam.

The Indiana bats at Tippy Dam appear to be at the very northern edge of
their range. The recent discovery of a small number of Indiana bats
hibernating and swarming at Tippy Dam (Kurta and Teramino, 1994; Kurta,
1995b) extended the known range of this species almost 200 km northward
in the Midwest. The summer range for the Indiana bats that hibernate at
Tippy Dam is unknown.

The existing Tippy Dam spillway appears to provide suitable temperature
and humidity conditions for the species that hibernate there and human
disturbances during the fall and winter are rare. Access to the spillway
is limited and controlled by CPCO. The habitat surrounding Tippy Dam is
wooded and appears to supply adequate roosting habitat for bats during
swarming. Much of the land near Tippy Dam is controlled by CPCO and the
U.S. Forest Service. Agreements have been made with both parties to
consult with the Service prior to any activities that may affect the
Indiana bats and to maintain suitable habitat near the dam. Further
details on habitat management are available in the Indiana Bat
Management Plan (Kurta, 1995c) and Manistee River Land Management Plan
prepared in compliance with the FERC requirements for relicensing the
CPCO hydropower facilities at Tippy Dam.

Indiana Bat Management Plan

In response to Article 412 of the FERC\'s relicensing order of 15 July
1994 for Tippy Dam, a management plan for the Indiana bat at Tippy Dam
was developed . The Indiana Bat Management Plan represents Part V of the
Manistee River Land Management Plan for Tippy Dam (FERC Project No.
2580) that was filed with FERC on 16 January 1996. The plan for the bat
addresses two major threats to the continued existence of the species at
Tippy Dam: 1) disturbance to hibernating bats and 2)
destruction/degradation of nonhibernating bat habitat.

Disturbance during hibernation is a major threat to any species of
hibernating bat (Speakman et al., 1992; Thomas, 1995a), because such
disturbance may cause a bat to arouse (to raise its body temperature to
a normal, active level of about 351 C) and use its limited fat stores at
a rate faster than normal. If these fat stores are depleted before the
return of flying insects in spring, the bat will die of starvation
(Brigham, 1987; Lyman et al., 1983). Consequently, to prevent
disturbance to hibernating Indiana bats, the plan prohibits unnecessary
entry into the spillway between 1 September and 1 June of each year. The
plan also prohibits unnecessary operation of the spill gates during the
same period. Operation of the gates causes a large amount of water to
enter the interior of the spillway through the lower ventilation
openings, resulting in a significant increase in noise levels and
presumably a sudden change in air temperature and humidity, as well as
an increase in air currents.

To protect any Indiana bats that may roost outside the spillway during
the summer and swarming seasons, the plan prohibits tree‑cutting on
Tippy Project lands, from 1 May through 1 October of each year. Use of
pesticides is prohibited during this same period to prevent
contamination of the bat\'s food supply (insects). In addition, the plan
mandates the preservation of a suitable density of potential roost trees
(\>0.4/acre) on forested portions of Tippy Project land.

The plan also calls for monitoring population trends and environmental
parameters to establish baseline conditions. Population monitoring began
in February 1995 and recordings of temperature and humidity were started
in August 1995 and both studies ended in June 1996. Figures 5‑9 in the
BA show some of the most recently compiled results of these surveys. The
Indiana Bat Management Plan requires monitoring both population levels
and environmental parameters during the hibernation season (1997‑1998)
immediately following the spillway rehabilitation work described in the
next section; such monitoring will allow CPCO and resource agencies to
assess potential long‑term effects of the project on all bats within the
spillway, and especially the endangered Indiana bat.

**Effects of the Action**

Overview

Effects on the bats could either be immediate or long‑term. Immediate
effects primarily would involve the disturbance of bats that are
roosting in the dam during construction activities; these effects must
be analyzed according to three seasons of the year when Indiana bats
would utilize the spillway‑‑\"summer\" (June‑August), swarming
(August‑September), and hibernation (September‑May). Long‑term effects
are those that might change the temperature and/or humidity inside the
spillway. There are no interrelated, interdependent, or cumulative
effects anticipated.

Immediate Effects

Summer - In Michigan, bats that roost in cavelike environments during
summer are adult males and nonreproductive females, although late in the
season (August), these bats may be joined by postlactating females;
hence any effects of construction during this time would not impact
reproductive females. Furthermore, very few bats of any species use the
spillway during the day in June, July, and August (FERC 1996), and no
Indiana bats have been identified roosting in the dam during this summer
period (Kurta, 1995b). Construction activities quite likely would
disturb individuals that might roost in the spillway, forcing them to
move elsewhere. Alternate roosts (trees), however, should be readily
available nearby, in the surrounding Manistee National Forest and the
small amount of Tippy Project land owned by CPCO. Consequently,
construction activities during June, July, and August are not likely to
have an adverse effect on roosting by Indiana bats. There should be no
adverse effect on foraging either, since Indiana bats forage primarily
in riparian and upland woodlands (Gardner et al., 1991; LaVal et al.,
1977) and would not be expected in the immediate vicinity of the dam.

Swarming - Swarming by bats is a nocturnal activity that occurs as a
prelude to hibernation and includes mating (Fenton, 1969). Swarming
typically occurs at very low levels in late July, increases slightly in
early August, and is at high levels in late August through most of
September, when actual mating occurs (Cope and Humphrey, 1977; Fenton,
1969; A. Kurta, unpubl. obs.). Since swarming takes place only between
dusk and dawn, construction activities occurring between dawn and dusk
will have no adverse effect. This assumes that access points‑‑the
ventilation holes and the opening in the log chute chamber‑‑are left
unimpeded for the night, as the contractor will be instructed to do.
Construction will also occur at night through 15 August, potentially
interfering with swarming by a few bats that arrive very early in the
season.

However, there may be a pertinent difference among species in the timing
of swarming. Although Indiana bats leave hibernation at the same time as
other species in spring, they apparently arrive at hibernacula, in
Indiana and Kentucky, 2‑3 weeks later than little brown bats (Cope and
Humphrey, 1977). If this difference exists at Tippy Dam, then most and
perhaps all Indiana bats arrive after 15 August, and it seems that
nighttime construction activity at Tippy Dam, prior to 15 August, is not
likely to have an adverse effect on Indiana bats. In any event, the
nocturnal disturbance to all bats will cease well before the mating
season begins and before a hibernating population begins to build in
early September.

Hibernation - (Spring Construction) - Construction activities, beginning
with installation of the cofferdam, are slated to start as early as 5
May. The bats are leaving hibernation at this time of year, and the
population declines from near 20,000 in April, to about 7,000 on 7‑11
May, to less than 100 by 24 May (FERC 1996). Hence a large number of
bats are likely to be present when cofferdam construction begins, and it
is reasonable to assume that some of these may be Indiana bats, because
there appears to be no difference in timing of emergence between Indiana
bats and the other species (Cope and Humphrey, 1977). Reproductively
active female bats typically leave hibernation first (LaVal and LaVal,
1980), and those remaining in the spillway in early May appear to be
adult males (Kurta, 1995b).

Installation of the cofferdam, particularly the installation of 75‑100
concrete anchors, may create noise that is detectable within the
spillway, despite the high background noise levels. Unfortunately the
effect of noise alone on hibernating bats is not clear. Thomas (1995a)
demonstrated that humans simply walking through a hibernaculum could
induce arousal in a few bats. These aroused bats would, in turn, disturb
other bats, who would then disturb even more bats. This cascade effect
resulted in heightened activity within a hibernaculum hours after the
humans departed. Unfortunately, the exact stimulus that led to the
original arousals is not known. It could have been sound, light, air
currents, slight changes in air temperature, or some combination of
these variables.

Speakman et al. (1991), in contrast, demonstrated no reaction during
hibernation by six European species of bats to a variety of sound
stimuli presented in the laboratory. Harrison (1965) showed that
peripheral nerves of the little brown bat ceased conducting impulses at
a body temperature of 12 1C, possibly making the animal functionally
deaf while in hibernation. Twente and Twente (1987) cited unpublished
data indicating that certain sounds did not arouse hibernating big brown
bats (Eptesicus fuscus) in the laboratory. However, as Thomas (1995a)
pointed out, bats tested in the laboratory generally were in hibernation
for only a short time since their last arousal, and bats appear most
sensitive to stimulation late in a torpor bout. Hence, the question of
whether sound alone is sufficient to arouse a hibernating bat has not
been definitively answered in the scientific literature.

At Tippy Dam, the two‑foot‑thick concrete walls and small exterior
openings should minimize the passage of airborne sounds into the
spillway, but installation of concrete anchors, using a rotary impact
hammer, conceivably will transmit noise and vibrations through the walls
of the spillway. The effects of this noise and vibration on hibernating
Indiana bats are difficult to analyze, because the noise and vibration
cannot be quantified (e.g., intensity, frequency, and duration of
individual sounds, repetition rate, etc.) prior to construction. Given
the sensitivity of some bats to disturbance during hibernation, the
inability to characterize the sounds in advance, and the limited
literature on the subject, one must conservatively assume that some bats
at Tippy Dam may be disturbed by these rehabilitation procedures and
temporarily arouse from hibernation as a result.

What are the consequences of a temporary arousal? An unscheduled arousal
from hibernation is generally believed to be harmful because it requires
an inordinate amount of the animal\'s stored fat to be expended. Just
one arousal lasting a few hours can use up as much stored fat as 68 days
of continuous hibernation (Thomas et al., 1990), and if a bat\'s fat
supplies are depleted before the return of flying insects in spring, the
animal will die of starvation.

As cofferdam construction proceeds, repeated disturbances and subsequent
arousals over a number of days appear likely, and it is possible that at
least some bats will be prematurely forced to exit the dam in search of
food. Even though two‑thirds of the bats have already left hibernation,
insect abundance is generally lower in spring compared to summer, and
the sudden addition of an unknown number of hungry males into the
foraging population could result in heightened competition with other
bats for a limited resource. Such competition could conceivably affect
the survivorship of some bats and/or the reproductive success of
females, who are pregnant at this time. In the absence of contrary data,
one must assume that construction‑related disturbances and the
premature, seasonal arousal of bats that might result may have an
adverse effect on a small number of Indiana bats.

Late Summer Construction -Construction will end with testing of the new
spill gates by 5 September and removal of the cofferdam by 12 September.
Testing of the new spill gates will result in water suddenly entering
the tumble bay; the water will then flow into the interior of the
spillway through the lower ventilation openings. This ultimately creates
much noise inside the spillway, possibly changes the air temperature and
humidity, and likely increases air currents. Previous observations
suggest that opening the spill gates greatly disturbs torpid bats in
summer (Kurta, 1995b, pers. obs.), and it is reasonable to assume that
this occurs during hibernation as well.

Unlike winter and spring populations, many roosting bats (estimated at
5‑10%) in September and October hang on the lower half of the walls of
the spillway (A. Kurta, unpubl. obs.). During spills, water may rise 19
feet within the spillway, possibly engulfing bats that roost low on the
walls, before the bats can warm and fly away. Testing the new gates will
involve only the volume of water between the spillway and the cofferdam,
and this amount of water might not rise to maximum levels within the
spillway. Nevertheless, the potential exists that some bats may drown
during the gate testing. A number of dead bats were seen floating in the
tumble bay on 18 March 1995 following operation of the spill gates (K.
Stubbs, M. DeCapita, and A. Kurta, pers. obs.), although it was not
possible to determine whether those bats had drowned or whether they
were already dead and had been washed out during the spill. Mortality of
Indiana bats, resulting from floods while in hibernation, is documented
for natural cave populations (DeBlase et al., 1965; Hall, 1962).

Testing of the new spill gates, therefore, is likely to have an adverse
effect (drowning) on a small number of bats, potentially including
Indiana bats, but this effect may be lessened by appropriate timing of
the gate testing. About 70% of the 1,078 bats present in the spillway
during the day on 8 September 1995 had not yet entered hibernation, and
they left to forage after sundown (A. Kurta, pers. obs.). Consequently,
the gates will be tested between one and two hours after sunset, to
minimize effects on the bats. Since insectivorous bats do not forage on
wet or cold nights (Barbour and Davis, 1969), testing will be done on a
night with no rain and, if possible, when external air temperatures
exceed 101 C (501 F) at sundown.

Cofferdam removal will occur after the new gates are successfully tested
and will involve cutting away the sheet piles with torches, but leaving
the concrete anchors in place. The noise and vibration associated with
this activity and the potential disturbance to the bats would certainly
be less than cofferdam installation. Unfortunately, it is not possible
to predict the intensity, frequency, and/or duration of sounds that
actually will be generated by removing material from the water, placing
it on heavy trucks, and hauling it away, or the level and type of noise
that will be created by site‑restoration activities that are scheduled
to occur at the same time. Consequently, one must conservatively
conclude that the level of disturbance will be sufficient to disturb the
1,000‑2,000 bats that roost in the spillway, including some Indiana
bats.

The bats that have already entered hibernation by this time may be
aroused by the disturbance, but the ultimate effect of an artificial
arousal from hibernation at this time of year is unknown. Although the
bats would consume excess amounts of fat during the arousal process, it
is not clear whether they would attempt to restore that fat by more
foraging, and if they did, whether they would be successful. Flying
insects become scarce late in the year, because of cool nighttime
temperatures, making foraging less productive and perhaps leading to
competition with bats that have not yet started to hibernate. In
addition, most bats are sensitive to repeated disturbance at their
roosting sites (Barbour and Davis, 1969), and activities scheduled for
the first part of September could force some bats to abandon the
spillway and search for a more peaceful place to hibernate. Such a
search may not be successful, given the lateness of the season and the
lack of other hibernacula in Lower Michigan.

Effects of Construction Delays

The proposed schedule (FERC 1996) has major demolition and
rehabilitation activities continuing up to 5 September. Any delay,
caused by weather or other factors, will push this work later into
September, when 1,000‑2,000 bats have reoccupied the spillway (FERC
1996). It is reasonable to assume that some of these activities will
disturb the bats, especially the installation of the new gates and deck,
which will be occurring on top of the spillway itself. This disturbance,
of course, would be in addition to that already discussed concerning
gate testing, cofferdam removal, and site restoration.

As mentioned earlier, the ultimate effect of disturbance at this time of
year is unknown. Conceivably those bats already in hibernation will
arouse and deplete fat stores, but it is not known whether those
individuals would be able to replenish their fat stores before flying
insects disappear for the winter. Also, repeated disturbance to
hibernating or nonhibernating bats likely would force some individuals
to leave and search for another hibernaculum. The number of bats
affected by delays will likely be greater than if the project were
completed on time, because the period of disturbance is longer and a
greater number of bats are present (FERC 1996).

Potential problems associated with delays will take on extreme
importance, if the end of construction is pushed into late September and
October. The rapid buildup in the hibernating population from about
1,900 to 20,000 bats between 23 September and 20 October (FERC 1996),
combined with the relatively large proportion of bats that roost low on
the walls at this time, could lead to significant disturbance and direct
mortality when the new spill gates are tested.

Long‑term Effects

Temperature - The spillway will retain its original configuration, wall
thickness, and ventilation openings, and the addition of ballast, if
required, will not interfere with airflow in and out of the spillway.
Hence no changes in internal ambient temperature, resulting from the
rehabilitation, are anticipated in future years (FERC 1996). Although
the interior of the spillway may warm more than usual during the summer
of construction, this should be countered by the arrival of cooler air
(cooler than the water) in September followed by the restoration of
water adjacent to spillway. Internal temperatures are likely to return
to \"normal\" following a short equilibration period after
rehabilitation activities are completed.

Humidity - The installation of new gates, rehabilitation of the
concrete, and sealing internal cracks and joints likely will eliminate
much of the water that currently flows down the internal walls of the
spillway (FERC 1996). Although some water may continue to flow through
the bottom of the spillway, such flow may be affected by the addition of
extra ballast. Consequently it is conceivable that the relative humidity
within the dam may change.

Most Indiana bats hibernate in areas where the relative humidity is
greater than 85% (Hall, 1962). Attempting hibernation in too dry of an
environment may lead to an increased frequency of natural arousals,
because water loss during hibernation is believed, by some, to be the
primary cause of natural arousals (Thomas and Cloutier, 1992; Thomas,
1995b). An increased frequency of arousal, whether induced by
disturbance or by evaporative water loss, leads to depletion of fat
reserves and lessens the bat\'s chances of surviving the winter. It is
not certain whether a change in humidity will actually occur following
rehabilitation, nor is it possible to predict what the magnitude of such
a change might be. Nevertheless, to be conservative, one must assume
that a change will occur and that it may be of sufficient magnitude to
have an adverse effect on hibernating Indiana bats. However, humidity
will be monitored and methods to increase humidity will be investigated
if necessary.

Summary of Potential Effects of Proposed Activities on Indiana Bats

1\. Summer Roosting. There is not likely to be an adverse effect on
Indiana bats that roost in the dam during June, July, and August, when
most of the construction will occur, because the total number of bats
that occupy the spillway is very low, no Indiana bats are known to use
the dam during these months, and, most importantly, alternate roosts are
readily available.

2\. Foraging. There is not likely to be an adverse effect on Indiana
bats during foraging because their preferred habitat is riparian and
upland woods, and they would not be expected to forage in the immediate
vicinity of the dam.

3\. Swarming. There is not likely to be an adverse effect on Indiana
bats during the swarming season, because access points (i.e.,
ventilation holes and the opening in the log chute chamber) will be left
unobstructed during nighttime hours after 1 August, and nighttime
construction activity will cease by 15 August, which probably is prior
to the arrival of this endangered species.

4\. Spring Construction and Hibernation. Construction activities
occurring in May may have an adverse effect on some Indiana bats by
inducing arousals, depleting body fat stores, and perhaps prematurely
forcing some bats out of hibernation and into competition with pregnant
females and other bats that have already aroused.

5\. Late Summer Construction and Hibernation. Construction activities
that extend into September (cofferdam removal and site restoration) may
have an adverse effect on some Indiana bats, by inducing arousals and
forcing some to abandon their roost at a difficult time of year. Testing
of the new spill gates may have an adverse effect by leading directly to
death by drowning.

6\. Construction Delays. The effects mentioned in #5 will be
exacerbated, due to the greater number of days on which disturbance may
occur and the greater number of bats potentially affected, if
construction is extended beyond 12 September.

7\. Long‑term Changes in Temperature. The spillway will retain its
original configuration, wall thickness, and ventilation openings (but
see Mitigation), and there should be no changes in internal ambient
temperature that would affect Indiana bats.

8\. Long‑term Changes in Humidity. Rehabilitation will lessen the flow
of water inside the spillway, perhaps lowering the relative humidity
below 85%, which may have an adverse effect on hibernating Indiana bats
by potentially increasing evaporative water loss and the frequency of
natural arousals.

9\. Cumulative Effects. Cumulative effects are not anticipated.

Effects on the Continued Existence of the Species

The preceding, conservative analysis indicates that some of the
construction/rehabilitation activities associated with the spillway at
Tippy Dam may have an adverse effect on Indiana bats during hibernation.
The dam, however, is on the extreme northern edge of the species\'
distribution in the Midwest, and consequently, the total number of
Indiana bats using the spillway structure is very low. The hibernating
population at Tippy Dam, during midwinter, is estimated to range from 3
to 65 bats, with the actual value probably on the lower end of this
range (Kurta, 1995b). The number of Indiana bats that may be affected by
construction/rehabilitation activities is likely to be less than the
maximum number present in midwinter, if the project is completed on
schedule. This is because most activities that could impact the bats are
scheduled to begin after most bats have left the spillway, and to end
before most return. If construction is delayed into October or November,
it is likely that all Indiana bats at the site would be affected. Based
on criteria presented in the current Recovery Plan for the Indiana bat,
the Recovery Team likely would classify the spillway as a Priority 4
hibernaculum (the lowest priority), indicating that the spillway has
\"marginal significance\" (USFWS, 1983:I‑2). Hence, even in the very
unlikely event that all Indiana bats hibernating inside the spillway
were \"taken,\" this action is not likely to jeopardize the continued
existence of the species.

**Cumulative Effects**

Cumulative effects include the effects of future state, local, or
private actions that are reasonably certain to occur in the action area
considered in this biological opinion. Future Federal actions that are
unrelated to the proposed action are not considered in this section
because they require separate consultation pursuant to section 7 of the
Endangered Species Act.

There are no anticipated non-federal actions that would affect the
spillway or Indiana bats. Most of the land surrounding Tippy Dam is
controlled by CPCO through a FERC license, or the U.S. Forest Service.

**CONCLUSION**

After reviewing the current status of Indiana bats, the environmental
baseline for the action area, the effects of the proposed rehabilitation
of the Tippy Dam spillway, and the cumulative effects, it is the
Service\'s biological opinion that the action, as proposed, is not
likely to jeopardize the continued existence of the Indiana bat.
Critical habitat for this species has been designated. However, this
action is not near any designated areas and no destruction or adverse
modification of critical habitat is anticipated.

**INCIDENTAL TAKE STATEMENT**

Sections 4(d) and 9 of the Endangered Species Act, as amended, prohibit
taking (harass, harm, pursue, hunt, shoot, wound, kill, trap, capture or
collect, or attempt to engage in any such conduct) of listed species of
fish or wildlife without a special exemption. Harm is further defined to
include significant habitat modification or degradation that results in
death or injury to listed species by significantly impairing behavioral
patterns such as breeding, feeding, or sheltering. Harass is defined as
actions that create the likelihood of injury to listed species to such
an extent as to significantly disrupt normal behavior patterns which
include, but are not limited to, breeding, feeding, or sheltering.
Incidental take is any take of listed animal species that results from,
but is not the purpose of, carrying out an otherwise lawful activity
conducted by the Federal agency or the applicant.

Under the terms of section 7(b) and section 7(o)(2), taking that is
incidental to and not intended as part of the agency action is not
considered a prohibited taking provided that such taking is in
compliance with the terms and conditions of this incidental take
statement.

The measures described below are nondiscretionary and must be
implemented by the agency so that they become binding conditions of any
grant or permit issued to the applicant, as appropriate, in order for
the exemption in section 7(o)(2) to apply. The FERC has a continuing
duty to regulate the activity covered by this incidental take statement.
If the FERC (1) fails to require the applicant to adhere to the terms
and conditions of the incidental take statement through enforceable
terms that are added to the permit, and/or (2) fails to retain oversight
to ensure compliance with these terms and conditions, the protective
coverage of section 7(o)(2) may lapse.

**AMOUNT OR EXTENT OF TAKE**

The Service anticipates that incidental take of all Indiana bats
utilizing the Tippy Dam spillway may occur in the form of harm or
harassment through disturbance and habitat modification. Some
disturbance of the bats may be unavoidable if the project is to be
completed in time for hibernation of bats in the fall of 1997. The
proposed action may also kill Indiana bats by drowning during spillgate
testing. The disturbance and modification of habitat may significantly
impair the essential behavioral patterns of the Indiana bat, including
breeding, feeding, and sheltering. If the disturbance and modification
of habitat causes Indiana bats to seek other hibernaculum, the bats are
not likely to survive. However, mortality and harassment of the Indiana
bats will be greatly reduced if the action is completed within the dates
specified in the BA.

It is possible that unavoidable construction delays may eliminate or
reduce suitable habitat for hibernating bats at Tippy Dam during the
fall and winter of 1997-98. This could result in the incidental take of
all Indiana bats that utilize the dam, because there are no known
suitable substitute hibernaculum nearby. The exact number of Indiana
bats at the dam is not known, but is estimated to be 3-65 individuals.

**EFFECT OF THE TAKE**

In the accompanying biological opinion, the Service determined that this
level of anticipated take is not likely to result in jeopardy to the
species or destruction or adverse modification of critical habitat.
Incidental take of the 3-65 Indiana bats associated with the proposed
action is not considered a prohibited taking provided that such taking
is in compliance with the terms and conditions of this incidental take
statement.

**REASONABLE AND PRUDENT MEASURES\***

The Service believes that the following reasonable and prudent measures
are necessary and appropriate to minimize take of Indiana bats:

1\. All reasonable efforts will be made to complete the proposed project
within the dates specified in the BA.

2\. Reasonable actions to minimize incidental take will be implemented
if unavoidable construction delays require rehabilitation activities
beyond the dates proposed in the BA.

**TERMS AND CONDITIONS**

In order to be exempt from the prohibitions of section 9 of the
Endangered Species Act, the FERC must comply with the following terms
and conditions, which implement the reasonable and prudent measures
described above. These terms and conditions are nondiscretionary.

1\. The contractors bidding on the Tippy Dam spillway project must be
made aware of the importance of completing the proposed action within
the dates specified in the BA and the ability to complete the project
within that time frame must be considered in the selection of
contractors.

2\. If unavoidable construction delays are known or anticipated to
extend spillway rehabilitation activities beyond the dates proposed in
the BA:

> A. The Service\'s East Lansing Field Office must be notified as soon
> as possible.
>
> B. If portions of the proposed action that would affect Indiana bats
> are delayed beyond September 15, 1997, construction activities that
> are not required for over-winter dam safety must be delayed until the
> following summer (or when Indiana bats are no longer utilizing the
> spillway).
>
> C. Spillgate testing must be delayed or water prevented from entering
> the hollow spillway, if Indiana bats are roosting low on the spillway
> walls when testing is scheduled.

The reasonable and prudent measures, with their implementing terms and
conditions, are designed to minimize incidental take that might
otherwise result from the proposed action. With implementation of these
measures, the Service believes that the frequency of incidental take
(harassment) of Indiana bats will be minimized, but that despite these
measures, all (3-65) of the Indiana bats are likely to be harmed or
harassed to some degree and possibly killed (see Effects of the Action).
If, during the course of the action, this minimized level of incidental
take is exceeded, (such as additional levels or forms of disturbance, or
greater numbers of Indiana bats are discovered) such incidental take
would represent new information requiring review of the reasonable and
prudent measures provided. The Federal agency must immediately provide
an explanation of the causes of the taking and review with the Service
the need for possible modification of the reasonable and prudent
measures.

**CONSERVATION RECOMMENDATIONS**

Section 7(a)(1) of the Endangered Species Act directs Federal agencies
to utilize their authorities to further the purposes of the Endangered
Species Act by carrying out conservation programs for the benefit of
endangered and threatened species. Conservation recommendations are
discretionary agency

activities to minimize or avoid adverse effects of a proposed action on
listed species or critical habitat, to help implement recovery plans, or
to develop information.

1\. Potential roost trees near Tippy Dam should be maintained and
managed for on a continuing basis. The number of potential roost trees
may not be limiting at this time, but timber management in the future
should consider the need for roost trees for thousands of bats during
the swarming period. The density proposed in CPCO\'s Indiana Bat
Management Plan (0.4/acre) is considered the minimum required for
suitable summer habitat. A density of at least 4/acre would provide
better habitat for bats and other wildlife and would be more consistent
with standards for snags used by the U.S. Forest Service on adjacent
lands.

2\. The Service supports CPCO\'s proposal to establish an educational
display near Tippy Dam for the public. The Service would like to offer
it\'s assistance and suggests coordination with the U.S. Forest Service
and MDNR for additional educational opportunities related to bats and
other species near Tippy impoundment.

**REINITIATION - CLOSING STATEMENT**

This concludes formal consultation on the proposed action outlined in
your BA and August 20, 1996, request for initiation of formal
consultation. As provided in 50 CFR \'402.16, reinitiation of formal
consultation is required where discretionary Federal agency involvement
or control over the action has been maintained (or is authorized by law)
and if: (1) the amount or extent of incidental take is exceeded; (2) new
information reveals effects of the agency action that may affect listed
species or critical habitat that was not considered in this opinion; (3)
the agency action is subsequently modified in a manner that causes an
effect to the listed species or critical habitat that was not considered
in this opinion; or (4) a new species is listed or critical habitat
designated that may be affected by the action. In instances where the
amount or extent of incidental take is exceeded, any operations causing
such take must cease pending reinitiation.

For the proposed spillway rehabilitation project, the Service has
authorized the take of all (3-65) Indiana bats thought to utilize the
spillway as a hibernaculum. This has been done with the understanding
that relatively few Indiana bats use the dam and the proposed project is
necessary for dam safety reasons. It is also with conditions that all
reasonable efforts will be made to minimize take and complete the
project before most bats begin hibernation in the fall. The Service
understands that the proposed project, like most major construction
projects, may experience delays that are unavoidable and result in
additional take of Indiana bats. It is important that FERC understands
that the authorization for take of Indiana bats at Tippy Dam should be
utilized only if necessary for public safety concerns.

Sincerely,

> Charles M. Wooley
>
> Field Supervisor

cc: FWS, Fort Snelling, MN (ES)

CPCO, Tom Bowes

USFS, Steve Kelly

MDNR, Tom Weise

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