MISSISQUOI NATIONAL WILDLIFE REFUGE

SWANTON, VERMONT

I -· t?tY/~,{41/l/ ~;/ I Cc;;; /Jfr /J h

ANNUAL WATER MANAGEMENT PROGRAM

2003

Prepared and --- ----------------­Submitted by Robert A. Zelley, Biologist

Reviewed by: Zone Biologist

Reviewed by: Refuge Operations Speci alist

Approved by: Refuge Manager

v/lzZ-,,r· ----

Date: ___ _

Date: __ _

Date: __ _

Date: ___ _

MJSSISQUOI NATIONAL WILDLIFE REFUGE P.O. BOX 163

SW ANTON, VERMONT 05488

I.A. ANNUAL WATER MANAGEMENT PROGRAM OUTLINE for CRANBERRY POOL Refuge: MISSISQUOI Water Unit Name or Number: #2 Maximum Elevation Permissible: APPROXIMATELY 98.80'MSL Flowline Elevation of Lowest Drain Structure: 95.00'MSL <Based on observations)

{f,P~~---Elevation of General Pool Bottom (not borrow pit bottom): 95.50'MSL

Table 1 (('! ... :-..:. t,1:1. rf Jr~JC- /l'IC.05urc~ ~,74 ~4tJt:.. tk/,_./ "° - , Water surface Elevations 2002 Planned Water Level for 2003

Jan 1 N/A frozen N/A frozen Jan 15 N/A frozen N/A frozen

Feb 1 Frozen Frozen Feb 15 Frozen Frozen

Mar 1 Frozen Frozen Mar 15 96.80' (actual 98.10)

April 1 Dependent upon Lake Level April 4 97.00 ' (actual 96.30) while lake level exceeds .. April 15 97 .65' (actual 96.95) 98.80' April 26 98.00 1 (actual 97.30)

May 1 Not taken 98.00 1

May 6 98 .50 1 (actual 97.80) Hold at this level until July May 9 98.35 ' 15tn for Black Tern nesting May 15 not taken May 23 98.35 1 (actual 97.65)

June 1 not taken qK,Dt> June 3 98.40 1 (actual 97.70 ' ) June 15 q I. ()O June 27 99.00 1 (actual 98.30)

July 1 not taken July 2 98.70' (actual 98 . 00) July 12 98.48' (actual 97.78) July 15 not taken 97.20 1

July 25 25 98.35' (actual 97.65) July 30 98.20' (actual 97.50) 97.20 1

IJ~!ldge BM reliabte, removed 2 stop logs

1

I"

2

Water Surface Elevations 2002 Planned Water Level for 2003

Aug 1 not taken 97.20 1

Aug 2 98.20 1 (actual 97.50') Put 1 stop log in . StU:tl!_Je is

o'' 8¥ •O. :;io£t &il!Jhez than aetual leue:i Aug 15 not taken 97.20 1

Aug 31 96.95

Oct 1 97.05' 97.20 1

Oct 15 not taken 97.20 1

Oct 16 96.90' Oct 29 97.20 1

Nov 1 not taken 97 . 20 1

Nov 15 97.20 1 96.00 1

Dec 1 not taken 96.00' Dec 4 96.60' frozen Dec 15 96.00'

I. B. VELS ON

l . Water Supply and Use During 2002 _ ~')-

~ -The Lake Champlain surface elevation did not rise as high as usu~ly in the spring due to reduced precipitation. The peak after ice-out was 98. 16 on April 22'{. The Lake Champlain level receded to a low of 97.62 on June 5th. Above average rainfall later in the spring brought Lake .. ~ •• ,

· I . y'&Jt~ J Champlain levels up to a peak level of 98.68' on June 17th. h/-.ct< f'T,.,,

'$~ - The Cranberry Pool was held at 98 ft, msl at the request of Nat Shambaughtfo provide optimun nesting conditions fo1'ack@ms that use the .impoundment. Nat had observed that the impoundment was particularly important to Black Tern nesting success in·years when the lakeshore marshes were flooded at higher than average levels. Since we have been unable to achieve-the 97.20' objective level most of the time in past years until June, we agreed to try this and the pool level was held higher until about the third week ofJuly. The level was lowered to 97,20' through the remainder of the year. (Need to mention if any Black Tern response to management in 2002 when/ obtain marshbird data from Peter or Nat.)

In July, it was verified that the water level gauge at Cranberry Pool was not accurately measuring the water level. Apparently, the steefi'b~am on which the gauge is mounted had settled ~ into the substrate due to ice action. The gauge reads 0. 70 ft higher than the true water level in the

~ ,~ impoundment. Corrected levels are indicated in parentnesis in table 1. t -~In late Nov~mber it was realized that the water control str\icture was completely plugged with

sediment and wood debris. The operung was clear:ed and the ppol allowed to drain for a week to try to flush some of the material out. The structur~ was closed on December 9, with the pool level at 96.60 ft. The 4 foot diameter pipe is over 3/~ plugged w~th sediment. It will be necessary to

3

excavate the area around it in the summer when the water level is low enough to work on the site. In the spring when the river level rises after ice out. the screw gate will be opened to allow a flushing effect through the structure.

2. Related Biological Conditions and Wildlife Use

r--- The current water management plan for the Cranberry Pool (WMU#2) recommends lowering the spring/early summer high water levels to 97.20'MSL as soon as possible, and holding that level throughout the year until November. In November, the levels are dropped down to 96.00'MSL, to reduce the flooding impacts of the following spring. Lowering the impoundment level down to the 97 .20'MSL objective has been intended to provide ground-nesting waterfowl with nestin~1Y.t~k~1 and grassed edge habitat that are otherwise underwater during the early April-May -neSUrig season here. This level also provides an optimum amount of interspersion of emergent vegetation and water. An excellent hemi-marsh condition is maintained at 97.20MSL and provides excellent waterfowl brood habitat and good feeding. nesting, and brood rearing conditions for other species such as black terns, moorhens, rails and bitterns .P.~he refuge varied this strategy in 2002 to accommodate a concern by Nat Shambaugh.@.lras monitored the Black Te_rns for many years. According to Nat, the Cranberry Pool has been af.lVm....e2U~nt ~esting area f~r Black Terns e~pecially /J/ J . during years when nesting sites on the lakeshore m'arsnes~tii not optimal~c. 4 /l"'b/""'I~ / 1-/:' /'1 t---The Cranberry Pool is critical to black terns in Vermont because: C>V- vt7 /6t.J WO. r .

/ a) It can serve as a refugia during high water years.,

\

b) It is protected from human disturbance. c) Water levels can be controlled.

(----- . .. ..... d) Vegetation can be managed if it is found to be necessary. ) e) The Vermont population is now almost entirely on the Refuge.

\ f) The Cranberry Pool is one of the few remaining area where black terns consistently \.. nest.

'=- It is thought that holding the Cranberry Pool level at 98.00 feet through the Black Tern nesting season would provide a stable and safe nesting area. When the surrounding marshes are

f r1 lo1\'fJ flooded a~ levels in the spring there is a lack of suitable nesting subs~r~J~~ i;t:edation potential is greater. The refuge area supports most of the Black Tern/ nestin~rlverlii~t~41~ince the refuge has been unable to lower the pool during _most years to the 97 .2 ft objective until sometime in June anyway, the risk to other species seemed low and it was agreed to hold the higher level longer for the benefit of Black Terns.· ·

We started lowering the poo! level in July. The Cranberry Pool was at 96.95 ft. msl. ,!z..,~ ,,A .~ Ar~ (R.eport ljere any info,,,fr'}fl Nat '£.intergs about Black Tern response) (,)er~-;: ,,--r-~

~ ,e/w ~-.,,A4-:;;.::::: ~ ~ r:~ war.;1e~M.:::.erally 1-3 feet lower during late summer and early fall . This outside level is influenced by the effects of heavy precipitation or dry conditions on the Missisquoi River watershed. During periods of low rainfall, the river is essentially at the same level as Lake Champlain. However, during heavy run off the river level may be one or two foet higher than the lake

4

for a brief period of one or two days. Waterfowl use of the impoundment was typical except for the preseason banding effort.

There appeared to be a change in use of the Cranberry Pool by waterfowl during the summer banding effort. There were fewer waterfowl coming to either of the two baited net sites. The cause of this change in waterfowl behavior is not clear. It may be that some bird of prey such as a Great Homed Owl or possibly a Bald Eagle had spooked the birds away from using the sites. Gross observations of the pool did not reveal any changes in vegetative cover or other physical change that could explain the situation.

A vegetation survey of the Cranberry Pool such as was done in 2000 has not been repeated since that year. It would be desirable to complete another survey in 2003 in order to detect any changes in aquatic vegetation density or distribution.

The table shows a dominance of wild rice and button bush but also, a healthy variety of other aquatic plants. Some oft he aquatic plants were beginning to show senescence at the time of the 2000 survey in late August of that year and may have been under represented by the survey.

5

Table 1. Average percent covers for plant species identified during the Fall of2000, in Cranberry Po 1 Mi . . 0, ss1sauo1 NWR, Swanton, Vermont.

Species Average Species Average Percent Percent Cover Cover

Water 66.41 Duckweed 1.39

Wild Rice 29.45 Red Maple 1.36

Buttonbush 16.81 Yell ow Pond Lily 1.35

Arrowhead 9.61 Pickerel Weed l.18

Carex Species 9.61 White Oak 0.52

Pennsylvania 9.02 Grass Species 0.43 Smart weed

White Water Lily 8.39 Water Smartweed 0.26

Coon tail 7.07 Great Bur-reed 0. 14

Purple-leaved 3.26 Sensitive Fem 0. 12 Willow-herb

Soft-stemmed 3. 14 Ragweed 0. 11 Bulrush

IC. STATEMENT OF OBJECTIVES FOR THE PROPOSED LEVELS IN UNIT #2~,,6,. '7 /'J ~ The elevation of 97 .20 msl will provide opportunities ,to optimize management for species

diversity in Cranberry Pool . This elevation allows waterfowl, black terns, rails, and other wetland dependent species predator-reduced nesting opportunities. Water levels are shallow enough in early and mid summer for effective brood rearing as the water warms and invertebrate biomass expands. Wild rice, button bush, bulrush, and other aquatic plants all flourish in the impoundment and provide a good substrate for invertebrates as well as seed production for the fall migration. Many of Vermont's threatened, endangered, rare species, and species of special concern use this impoundment during at least a portion of the year. The refuge will strive to achieve water levels that continue to optimize wildlife use in 2003.

The fluctuations in the level of the water in the Cranberry Pool are important to the long term health of the aquatic community that it supports. The stated objective level in this plan is rather static. However, it is expected that the level will naturally be higher in the spring. The over topping of the west side of the pool by spring flooding combined with a variable amount of sustai.ned high water from year to year may be an important factor pertaining to the management of the wetlands enclosed by the Cranberry Pool dike. The variability of the water level favors aquatic plants which

6

are adapted to this seasonal flooding. The dike system helps to moderate the extremes of very low water levels. During those years when some of the potential ground nest sites in the pool are unavailable to nesting waterfowl, this may be partly mitigated with dense nesting cover in the adjacent old fields and elsewhere on the refuge.

- ~A planned draw-down will be attempted at five year intervals unless drought conditions have caused the same effect within a five year interval. The last draw-down occurred in 1999 due to below normal rainfall. The next draw-down will occur on or before 2004. lf1lor1trl L ·--The water level that is held at the onset of winter, can either be at the 971 level or 961~P'J Rechawr,~/~jmR&~2dment will be possible at least to the 97.20' level in any case. During years, when tn6'river at&not nse enough to over-top the bank and flood the pool, it would still be possible to let water in through the screw gate on the new water level control structure. The 97' foot level is being considered when it may be desirable to increase muskrat survival. The muskrat population can be a tool for maintaining a optimum interspersion of water and marsh vegetation. ~A total of361 muskrats were trapped from the Cranberry Pool dike in November of2002. The Cranberry Pool was left at 96.5' msl by the end of December. This level is higher than the

surrounding marshes due to the lower than normal level of Lake Champlain. The water level in the pool may increase winter survival of muskrats

Table AC - f ompanson o h rvest. k h d mus rat ouse counts an traomn2 a

Calendar Year Jan - March House Fall Trapping Count Harvest

2000 no count taken none*

2001 78 682

2002 397 361

Jan 2003 525

*trapper elected not to trap because of high water in the impoundment.

There are three places to monitor water levels: Charcoal Creek, Mac's Bend Bulkhead, and a gauge mounted on a post inside the Cranberry Pool. The lake level at Charcoal Creek and the Pool Level inside the Cranberry Pool will be monitored at least twice a month. More frequent monitoring will be encouraged at these sites and at the river elevations during the spring ice-out and high water run-off periods. Lake levels from the King St. ~rry .Qock in Burlington are also recorded to supplement the local readings.

11. A. 2003 ANNUAL WATER MANAGEMENT PROGRAM OUTLINE FOR· WATER MANAGEMENT UNIT CWMU) # I - BIG MARSH SLOUGH & GOOSE BAY POOL

~~ Water Management Unit #I is comprised of Big Marsh Slough anl'Goose Bay Pool.

Due to the seasonal springtime high level ofL!!ke Champlain in'2002,_the water level in WMU #I was the same as Lake Champlain until about the end of July.

~/ ihJ .

H.B. ECOLOGICAL EFFECTS OF THE PAST YEAR'S WATER LEVELS ON WATER MANAGEMENT UNIT {WMU) #I

7

Big Marsh Slough and Goose Bay Pool continue to be treated as a single water management unit (WMU# I). They remain connected by a man made ditch between the two systems that was dug during the late 1960' s. Incomplete dikes, or "gut plugs" around the perimeter of these areas hold water levels once they drop below the 96.2S'MSL perimeter elevation.

The water level in the Big_ Marsh Slough dike cannot be manipulated because the WCS at Big Marsh Dike is completely nor\functional. To our knowledge, the WCS has not been functional for over 30 years. Management has been centered around retaining as much water as possible, for as long as possible. The original plans called for complete diking of the periphery of this unit. Since the original construction a~tivity in 1950s, a dike system of the magnitude originally envisioned might not be viable from a cost/benefit perspective. Therefore, this unit functions in accordance with the water levels of Dead Creek and Lake Champlain, until its water level drops below the approximate perimeter elevation of96.25'MSL. Beaver activity in recent years has helped to retain water levels above 96.2SMSL in WMU# l.. '

rbe eeAAeeiing ditcb between Bjg Marsh Slo119h aAi ~QQH .ea~: P6Htl "'18"1io0000 91jj hy ....bea·~f8 SYRA8·1QQ9, ancJ ... h&eoheea mdthtalh!ft by beavers smcttnerr: :!ilrcc the salaiheld a miait him

Qf2"-4" more watetzjp QQQEO ~9' Pool, i• hai "8Utl +>eon :unwed until iQQ~-MlattRQ'l'L:ha9iitat iA"1009e'Bay"Pe'7i·i'S'itnpt0ve:!d"by-th~~·"rt•rgh~alCI MeMi: +his ee&:'IF aam u:ae :aplac(Q bi}'

.> sterJ ~b~~tJli~arrier in 200 I durin,i r599uailiilss •8'ftt~HeuQey.~ThC"Sheerpitmg-was 'T"T ... ~--,, t

e¥C81ili waao.-11 IMOH nmaued fr0 m sh ••a•~ 1 ilJ Peel ia !OMJ &lid \tt!"i M'J elecf. Benchmark water levels were establishe on June ~7~. It was a calm day and the assµmption

was made t at t e a e eve wast e nown benchmark, Charcoal Cree~, and. the connector ditches at Big Ma~sh. J:ht. top of the sheet-pile on the Big Marsh side of the structure is 98. 95 ft msl. On the Goose Bay side of the structure it is 99.03 ft msl. The different elevations on either side of the structure result from the top plate being a little twisted. A few efevation measurements of levels in Big Marsh Slough and Goose Bay Pool were made during the summer ~nd fall. .

Water Levels in WMU # I during 2002

Date Big Marsh Slough Goose Bay Pool Lake Champlain

July 31 96.67' 96.9!i)' ~ 96.60' , ..

Sept 4 95.47' "': 96.27'. 9-4 .99'

Oct I 95.87' 96.52'.- 95. 14'

Oct 11 95.79' 96.43' 94.76'

The sheet pile stop log structure at the connector ditches is maintaining up to an 0.80 foot higher water level in Goose B~y Pool over Big Marsh Slough.

By referring to the monthly gauge readings for Lake Champlain, it can be inferred that the water level in the Big fyijrsh Slough was equal to Lake Champlain until the lake level dropped below . ~ the level of96.25' ms~he year 2002 was'Unusual for seasonal lake levels. The spring peak of the V

~~ke lev.el due te SR8Y/ welt aAd : a tT\vas lower than average. The peak level in April was 98.2 l ' / ~f!'tSn:t4f /r;,f;. /evdf JI? d~•J Wt°'"< t'/lllSw./ cl~ lo /J,e. v~"t 1111/J w1111<.r, 7"«/(/ t S/f/11/}c()/f/. v""""~ll q'/Jcl /~c/"cc.d o/"~-,.~ n:t./11fa1//n1e1)

~~ rc.r- I 'I .

uf~J 8

'(,{, ~on April 22nc1. The lake level subsided to a low of97.62' by June ~th . During June, over 5 inches of

rainfall brought the lake level up to a peak of9,8.68' by mid-June. The lake level gradually declined throughout the rest of the year to it's _lowest level' of 94 .. 54' on October 17th. Annual precipitation for Vermont totaled 29.0" ofsn~wfall and .36-71." of rainfall.in 2002.

2. Related Biological Conditions and Wildlife Use

Emergent vegetation was extensive throughout the Missisquoi Delta. The lake level rise and fall was not normal. Rainfall was below normal early on and above normal later in the spring. (Don 't have Black Tern nesting info yet from Nat) The only other nesting was by 6 pairs at the Mud Creek Wildlife Management Area 2 miles to the west in Alburg.(Nat Shambaugh)

The best brood rearing cover occurs in the impounded areas, Big Marsh Slough and the Cranberry Pool, as the lake level recedes.

The water level in the Cranberry pool was maintained near the objective level through the later part of the year. The impoundment retained water and allowed access to wild rice by migrating waterfowl. Submerged aquatics and emergents, such as pickerelweed, arrowhead, pondweeds, spikerush and duckweed added to the food sources for the ducks using this unit during the annual waterfowl population peak in October. As in past years, water lilies, water shield and burreed were also common throughout the unit. WMU# I continues to provide the highest concentration of ring­necked ducks on-refuge during October and November, and is well used by mallards and black ducks. Pied-billed grebes, moorhens, and rails are also known to breed and feed in this unit.

There is an area in Big Marsh Slough where Common Reedgrass was aerially sprayed in 1988. To date, there has been no new emergence of this pest plant. The area will continue to be

monitored annually to detect any growth of this plant.

Il . C. A STATEMENT OF OBJECTIVES FOR THE PROPOSED LEVELS

No objectives are set for this water management unit because there is no operable control structure for Big Marsh Slough. There is some ability now to mange a few inches of water level in the Goose Bay Pool if necessary. At this time the management of this area will be to allow Big Marsh Slough and Goose Bay Pool to retain as much water as possible when the Lake Champlain level recedes below the 96.25' threshold. These impoundments will be affected much the same as natural potholes such as occur on Metcalfe Island, Shad Island and Saxes Pothole. Water and vegetation will be monitored to document conditions during the year. The annual and seasonal fluctuations of the water level continue to provide the necessary stimulation to maintain the quality and diversity of cover beneficial to waterfowl and marsh birds .

~ll. A. 2003 ANNUAL WATER MANAGEMENT PROGRAM OUTLINE FOR THE ~ REMAINING REFUGE AREAS

Not applicable.

III. B. ECOLOGICAL EFFECTS OF THE PAST YEAR'S WATER LEVELS ON THE REMAINING REFUGE AREAS

I. Water Conditions During 2002

9

The year,2002, was a little different from the usual pattern of precipitation and lake levels. The peak lake level was lower than usual but rainfall later in the year maintained lake levels at about an average seasonal level in the summer and fall. There were essentially two peaks in the rise of the level of Lake Champlain. The peak from spring run off was only 98.21 ' on April 22nd. The lake level began to decline in May but peaked again on June 17th at 98.68' in response to above normal precipitation that month. The lake level followed a normal pattern through the remainder of the year reaching its lowest level on Sept 23'd. The lake level gradually rose to about 95.84' by early December an was at 95.58' by the end of the year.

Emergent vegetation in the refuge and its lake shore areas was as abundant as most past years. Wild Rice was evident in Gander Bay, Saxes Pothole, Metcalfe Pothole, Long Marsh Bay and Channel as well as being abundant in parts of Big Marsh Slough, Goose Bay Pool, and Cranberry Pool. Smaller patches of wild rice occur throughout the Missisquoi River Delta. Intermixed with pickerel weed, yellow water lily, other floating leaf and submerged aquatic plants. Dominant species included Hardstem Bullrush, Wild Rice, Pickerel Weed, Water Lily, and Burweed. Submerged aquatics are dominated by Eurasian Water Milfoil and beds of wild celery. lfe~ was vigilant during the year for any occurrence of water chestnut on the refuge. None was found. This invasive pest plant is located across the border in the Pike River and the South River. So far, it has not appeared in the northern part of Lake Champlain. If it does invade the refuge, it would wreck havoc with the native aquatic plants and quality wildlife habitat. A survey of purple loosest rife occurrence was done during the summer of 2002. The map below shows the general distribution of purple loosestrife. The plant's distribution has been relatively static over the past decade. However, the population located in the willow encroachment at the edge of the Tabor Road fields seems to have increased slightly.

p·urple Loos·es·trife 2002

li ~--~~~ffr-~~~·t

2 0 2 4 Miles ---

- Lythrum2002.shp D Wetland Boundary D Refuge.eo.undary /V' Roads

N

s

10

11

Muskrat and beaver populations appeared healthy. A count of Muskrat houses in the Cranberry Pool was done in February. A total of397 muskrat houses were counted in the Cranberry Pool. This was a conservative measure since it is likely that some houses were not detected in the snow and bank dens were not detected. A much fewer number of muskrat houses were counted in the other primary habitat areas ofBig Marsh Slough and the Clark Marsh on Charcoal Creek in 2002. A total of 361 muskrats were removed from the impoundment during the fall of 2002.

Muskrat House Counts

Year Cranberry Big Marsh Goose Bay Clark Marsh Total Count Slough Pool

2001 78 no count no count no count

2002 397 46 26 30 499

2003 525 97 (l/ 10/03) ( 1/06/03)

A survey of Beaver lodges was started during the winter in 2001 . Complete coverage was not made of all areas. Missed areas were Metcalfe Island and Gander Bay. A total of 17 Beaver lodges counted were distributed throughout the Missisquoi Delta. A survey of beaver lodges was completed in the winter of2002. There were a total of 20 lodges on the refuge in February 2002. Five of these were in Cranberry Pool. The population in this impoundment had died out until recently. Trapping beavers was resumed in the Cranberry Pool during the winter 2002-03 season. A total of 20 beavers were trapped from the impoundment.

HI . C. A STATEMENT OF OBJECTIVES FOR THE PROPOSED LEVELS

Not applicable.