Utah State University,
Logan, UT
16-18 September
1998
Present: Leigh
Fredrickson, Dave Hamilton, John Kadlec, and Rick Sojda
Is Bear River? - sort of
Caution: current habitats may not be optimum
There are more complexities in mountain systems
Hydrology
- mountains - groundwater recharge
- valleys - groundwater dischargeLarge aquifers - results in damping of seasonal cycles. There may also be some damping among years.
One given is that salt deposits mean groundwater
discharge basins. However, this does not mean that if it is not saline
it is not a discharge basin.
New agenda items
1. look at recharge vs. discharge basins
In discharge system, think about what happens when we take the surface water off. We're still managing surface water in relation to discharge hydrology.
2. Delineate where the system will be used
3. Users will have variable wetland expertise
Cowardin system main only marginally work in this part of the world, e.g., there is more variation in water supply, here.
Natural variability of hydrology and weather is greater here than in prairies. The dryer the climate the more variable/extreme the wetland conditions
In the Great Basin, there are probably as many basins that are wet 2 years out of 20 as there are basins wet 18 years out of 20.
The user/system should consider more than just vegetation and hydrology - also consider geographic location, altitude, etc. - i.e., Is this basin suitable for swans?
What species/life requisites are appropriate for this wetland?
What makes a wetland an historically important location for a particular species/life requisite?
One factor may be predictability of habitat on a regional basis
Size
Historically, swans used more productive
wetlands (for example, those in Iowa). Most wetlands used now are probably
marginal habitat.
Beaver Pond Habitat
Characterized by relatively stable water
regimes among and within years
provides predictable water long enough in relation to brood production
"stable in the natural sense"
Groundwater discharge probably required to maintain water (as permanent or semipermanent)
Most beaver dam areas suitable for swans are in lower gradient sections of streams, that is, wet meadows
Silt may be source of nutrients
Increase residency time of water
Different types of dams - swan habitat essentially found "only" in low gradient streams
Typical water regime
fall precipitation fills part way
ice bound over winter
ice-out and spring flood
dependent on altitude, anywhere between March and July
Typical, Natural Water Regimes in Semipermanent
Wetlands
We discussed beaver ponds to gain an understanding
of typical water regimes in unregulated, semipermanent, palustrine wetlands.
The following graph entitled, "Conceptual, mean water levels in beaver ponds of the Greater Yellowstone Area by elevation", is an attempt to depict the difference between "natural" water regimes at 5000 feet and 7000 feet for most semipermanent wetlands in this area. The graph represents an ice level at ice-out that is relative from year to year.
At 5000 feet (compared to higher elevations) there is less snow and therefore lower peak water levels; higher evapotranspiration and therefore lower low water levels; and generally less reliable water sources.
All beaver ponds that are important swan habitats are low gradient streams.
Ice-out at 7000 feet is typically in early May.
The following graph entitled, "Conceptual mean water levels and beaver ponds of the Greater Yellowstone Area by wetness condition", is an attempt to depict the difference between natural wet, average, and dry water regimes for most semipermanent wetlands in this area. A 7000 feet elevation was chosen.
Generally, folks were comfortable with
the direction of the graphs, but not the magnitude of the elevations.
Carex
Drier sites = exposed earlier
So germination may be earlier than Typha or Scirpus
Flower earlier and seed produced may germinate the year produced. But, not certain if seed produced in year 1 will/can germinate in year 1.
May need (but not certain) lower soil temperatures and higher soil moisture levels
These systems either have an outlet (flow through) or are recharge basins
"outputs"
- audience
* gun clubs -- specific water depths
* biologist -- let vegetation tell you what to do next
-what to look at
-what it tells you
to do
Next, we examined potential management schemes for several wetlandsbased on 90+ slides that Rick had of various wetlands in the Greater Yellowstone Area.
Case Study #1: National Elk Refuge
- Knowlin Pond 3
Assume a water control structure
2 - 2 ½ feet deep
Ice probably gouges at edge of emergent vegetation
Relatively flat to edge of basin
How much of basin could be inundated (for food resources)?
Probably not enough open water (for food resources); therefore, how can we increase open water
Therefore, increase water level above lip of ice rampart - this gives more open water as well as shallowly flooded zone for invertebrates
Flood so most vegetation has three to four inches of water. This will give initial burst of invertebrates.
When it starts looking like a lake, then go to a fluctuating water regime.
Watch to make sure we don't start getting cattail.
Might eventually get hardstem bulrush.
Is there a peat substrate? If so, raising
water levels might float the peat and therefore accomplish nothing.
DAY 2
Some General Comments
- Interpret current
condition in relation to what we want
- describing history -- what would we like to know
- what would we do now
- evaluate whether "successful"
(adaptive management)
More Knowlin Pond 3
Bring water up 2-4 inches (instead of
maximum flooding) and see what happens
-area affected
-response (for example, invertebrate response) (for example, bird response)
if primary focus is trumpeter swan nesting
-need large body of
water
-need submergent vegetation
-need emergent vegetation for nesting
-therefore, bring water all the way up to get rid of existing vegetation and create open water
-then start bringing water down to create the emergent vegetation
What if raising water level floats sedge mats over most of the area? Probably lower water level and look for another site because there are no good ways to address that problem (no good ways to predict ahead of time whether this would happen. However, if cores showed peat over coarse textures then maybe more likely.)
It is important to know if peat-based because it can influence things like pH.
It is important to build a history for area as a basis for decisions (decisions by system, decisions by users) - repeat site visits indicate additional questions to ask
General questions:
-hydrology onsite and
offsite
-legal constraints on water use - for example, have water rights but not available when needed during the year or not available in a dry year
-climate
* growing season - some of the plants we're dealing with have growing seasons longer than the traditional growing season (for example: if 40 days, then can get sedge, but probably not cattail or bulrush in an average growing season year)
* ET
* temperature
-vegetation (current,
seed bank)
Case Study #2: Island Park, ID -
Swan Lake
Water supply is unknown; probably not
much
Nuphar is compromising food production. May be siltation from road construction and deepening of channel that resulted in Nuphar establishment.
Sedge meadow implies peat accumulation
Could probably lower water level but not enough to control plants
It is likely to be expensive to get the kind of control needed
Is a sedge mat floating?
Could have been a sedge meadow originally, and highway berm created area of deep water
Cattail in middle probably won't expand
Case Study # 3: Red Rock Lakes NWR
- Wigeon Pond
Sedge meadow prior to diking
Good submergent community but no Sago
4-5 ft. deep at deepest, shallower bay (75 percent of total wetland?)
Some marginal stands of cattail or bulrush
Siltation not likely to be a problem
Looks pretty good for a nesting pair and brood of swans
Late drawdown (August or September) could make food resources available for fall birds; would stimulate submergents the following year, especially Sago; and would avoid germination of emergents. Probably don't want to flood back up after freezing because things frozen in ice would be pulled up. Therefore flood up before freezing or early in spring (right after ice-out) before emergents would germinate (all mudflats covered with at least four inches - probably means full pool)
Maintain full pool through summer
Check in late June to early July for response of submergents. Let amount of Sago tell you whether to drawdown again in late summer.
There are no carp in this system (but probably other fish)
Fish provide food for other birds.
Removing fish can increase nutrient supply for submergents. Removing carp can also help if you have turbidity problems.
Leaving water level low during winter is a good way to remove fish.
Objectives and strategy (habitat objective approach)
1. flood to maximum water level at ice-out for foraging habitat for prebreeding trumpeter swans and diving ducks
2. maintain maximum water level through ________________ for nesting trumpeter swans
3. initiate slow drawdown about July 15th to expose 10 percent of mudflats by freeze-up to enhance foraging habitat for fall staging ducks and cygnets and to stimulate germination of Sago for next year (and to avoid germination of emergents)
4. maintain low water levels through winter to decrease fish populations
5. monitor Sago in late June each year to determine percentage of mudflat to expose to increase Sago production
6. monitor water level weekly during the drawdown so that next year you can relate Sago production with conditions during the drawdown. By drawdown we mean the timing, rate, and condition.
***VERY IMPORTANT*** For each item in the above strategy, you need to specify what you're doing, when, and for what reasons.
Why not create a ring of cattail or bulrush?
- there is already nesting habitat for swans (the island)
- the deficiency is food for swans (that is, very little tuber production by existing submergents)
- such vegetation (cattail/bulrush)
maybe not needed for swans but would be used by redheads (but eventually
could reduce area of food production for swans)
Case Study # 4: Red Rock Lakes NWR
- Culver Pond
Some Sago but not a lot
Mineral soil substrate with gravel, therefore fairly sterile
Spring fed (no surface inlet) therefore continuous supply
Steep-sided
Control structure
Probably can't increase Sago much because substrate not ideal and constant water level means less opportunity to drawdown
Sago and Ruppia are good pioneering species when area is reflooded (for example, the Henry's Fork after it was denuded)
Trying a drawdown probably not useful because of coarse substrate and constant water
This type of area might be used as a staging area in fall if it were close to a nesting area. Might be used for prebreeding it Sago tubers present.
Generally, if percentage cover of Sago
decreases to 10-15 percent in a wetland, then probably time to implement
a strategy to increase Sago germination - best production in shallower
water with fluctuations
Case Study # 5: Red Rock Lakes NWR
- Tuck Pond
Unstable water supply - not much in late
summer (irrigation ditch from Red Rock Creek?)
May be salt on vegetation in one location, but no salt tolerant vegetation seems present
Historical swan nesting
Ceratophyllum may be present also possibly some Sago
You could get hardstem in this pond, so if you don't want it, you need to be careful
Need to monitor to see if vegetation patches are expanding, which would compromise swan food production
Probably not enough water to flood out hardstem if you get it
Might have to drop water in fall, mow, then reflood over top with inflows due to rainfall, which is probably not possible or at least reliable.
Don't want hardstem to compromise submergent production
No advantage to drying this pond earlier or more severely
We don't know enough about species composition and shifting composition among submergents to try to shift it
Monitor density of submergents and if severe drop (below 10 percent), consider changing management strategy
Literature is full of "we don't understand"
"If we were here two months ago, we might
have drawn different conclusions. The point is: be careful."
Case Study #6: Red Rock Lakes NWR
- Lower Red Rock Lake
There may have been more islands
Floating mats
Structure is basically a dam
Good staging area - fall (ice-out so late that spring migration not as important)
Clear that valley is discharge area hydrologically
One objective: expansion of bulrush and Carex aquatilis for nest sites for swans
Hemi-marshes may be better for production than staging. The value of hemi-marshes may be in decreasing turbidity which results in an increase of submergents and therefore use as a staging area
Too low of density of submergents happens when density gets so low that turbidity increases due to wind
Can we get water low enough to germinate
robust emergents?
- Try this in a dry
year.
- Get as much water off until you see old emergent island areas go dry. Seed bank should be there.
Muskrats - best way for managing bulrush marshes
Determining drawdown regimes: look at broad climatic/hydrology record -- like long-term hydrograph of Great Salt Lake
The smaller the watershed, the more variable the water levels, that is, both go dry and get flooded more frequently
Irrigation district records may have old weather records; also check Island Park Reservoir records
Precision of knowing the drawdown cycle
- more important to
introduce inter-year variability of water levels than long-term periodicity
- be opportunistic in
drawdowns
The shape of the outlet originally let more water out at high water levels. We then discussed the shape of wetland outlets in general, discussing some of the differences in natural "sheet flow" compared to WCS tube outlets. [Although there weren't many notes taken, the following diagrams are an attempt to capture what was discussed.]
Variability:
-- high (wet) end:
essentially stochastic [in mid and late summer especially]
-- dry end: always serially correlated with prior time period
-- look at long-term averages: this shapes system patterns; but, monthly events determine things like germination
What is the frequency of fluctuation that results in pattern of variability?
Within year variability due to previous snowpack
Dam - causes loss of low-end fluctuations, not the high-end
Look at last ten years of aerial photos
This concluded the case studies.
What Information Will the System Need to Understand Current Wetland Conditions and Make Recommendations?
In discussing these 15 items we combined several, and ended up with basically 13 categories.
Objectives
By guilds (guild did not seem to be the
correct term):
shorebirds, waders, puddle ducks, divers, marsh grazers
By life-cycle stage:
breeding, staging, migration, wintering
Prioritize among these
Hydrology
Surface water inflows: volume by season
Surface water outflows: law and by season
Sources of surface water: irrigation, permanent stream, ephemeral stream, spring
Groundwater:
discharge/inflow
recharge/outflow
Precipitation: monthly average and standard error
Evapotranspiration: monthly average and maximum
Legal requirements to store water
Water rights on supply
DAY 3
Bathymetry and adjacent topography
Percentage of basin or number of acres
in each one foot contour interval (include five feet above maximum water
height)
Type of water control structure: stoplog, radial gate, screw gate, flap gate
Drainable by gravity?
Vegetation
Species composition: the three most common
submergents and emergents
Distribution:
monotypic
clumped
bathymetrically zoned
Aerial abundance
An alternative to the combination of the above 3:
What is the dominant vegetation?
Information on trends, if available
Is the vegetation interspersed or not? Or, has it ever been?
Historical presence
of species, for example, maybe use a pull down menu of the major ones
Current snowpack
wet - medium - dry: examine distributions
[but not certain how to slice the probability distribution to represent
wet, dry, etc.]
Use to:
1. categorize which
set of recommendations for water levels to make (for example, dry year)
2. determine availability
of water for that year
Long-term climate
Keep this internal to system, that is,
probably don't need additional user input.
Altitude/latitude/growing season
At 45 degrees north latitude and 8000
feet MSL = limit to expect reliable germination of bulrush and cattail
May NOT need any other information
on growing season
Productivity
Do you have wetlands that may be relatively
sterile?
- if so, be cautious
of exporting nutrients
- if so, possibly the system will not make recommendations
If high possibility for contaminant concentration,
recommend permanent drainage.
Substrate/geomorphology
If watershed is basaltic, never do early
spring drawdown (to prevent export of nutrients)
If peat:
- Plants with high
need for nutrients, for example, would not do well [Sago, cattail, hardstem].
- Caution with flooding: do not float mats.
- It will likely be difficult to dewater except in driest of years, unless basin has been hydrologically altered.
If fine mineral (silt/clay):
- This provides the
best chance of success for manipulating water levels for plant communities
desired.
If coarse textured mineral (stand/gravel):
- Be cautious with
drawdown. Don't do it. Hard to keep surface wet without a lot of irrigation
effort.
- lower density of plants and drawdown
- fewer dicots
- may be good substrate
for Equisetum, but not sure why
Proximity to others
[size was handled earlier in bathymetry]
If a complex exists and is generally wet --> then best situation in which to drawdown a particular wetland
In a complex, manage a particular wetland
for the least common present condition.
Historic wildlife use
Important in relation to understanding
objectives and their potential achievement
Given the objective, is it reasonable to manage this wetland to achieve it?
What evidence exists that this objective has been met at some point in the past?
Are there other, rare plants/animals of concern? If yes, maybe shouldn't use the decision support system.
Muskrats:
Are muskrats present
or can they be expected?
- if yes, then can use for vegetation manipulation
- if yes, is harvest an objective?
What is the maximum number of houses per acre observed?
What is the current number of houses per acre observed?
Beaver:
If size of wetland
small, then difficult to have influence with active management.
Ice-out/freeze-up
Average ice-out date
Average freeze-up date
Use to set sideboards on water level manipulations
Use to match with wildlife objectives
Salinity
Need to know what the soil salinity is
- saturated paste reported
in EC
- pore water reported in milimhos
- ranges:
0-2 milimhos = fresh
2-20 milimhos = manageable
> 20 milimhos = salt grass and Salicornia; brine flies, brine shrimp, and
backswimmers
if soil is encrusted, then way above 20 milimhos
- at 0-2 milimhos: cattail and, especially latifolia, Sagittaria, Carex, Sparganium
- at 2-20 milimhos: mayflies, alkali bulrush, Ruppia, Sago, Zannichellia, Scirpus olneyi, Polygonum, Phragmites, baltic rush
As soon as soil surface is dry, soil capillary action results in drawing of water to surface, and therefore salt concentration at surface occurs. Therefore, any drawdown must be accompanied by flood irrigation. Flood irrigation can change this concentration so that cattail can germinate, and then it can take over.
Hardstem bulrush requires fresh conditions to germinate and get established, but it can then tolerate salinities in the midrange and expand vegetatively.
Cattail seedlings may be controlled by dropping water and therefore increasing salinity. This is true of most emergent seedlings, with common exceptions being Salicornia, alkali bulrush, and salt grass.
This ended the discussion of things
the system would need to know...
Miscellaneous Items at Conclusion
If there was no information on objectives,
the recommendation was to go no further in the DSS and stop.
Similarly, if water the information indicates "contaminants", the recommendation was to go no further in the DSS and stop.
Emergent control - might consider fire or grazing. Probably need to combine with subsequent water control. This combination often is not feasible due to lack of water supply.
Grazing - no good guidelines can be provided at this point. Grazing might be a way of providing foraging habitat. Cows do have a strong preference for alkali bulrush.
The following were cues indicating stable
water conditions:
Scirpus olneyi
High salinity plus stable water = NO emergents
Classic zonation pattern:
submergents
floating-leaved plants
emergents
sedges
[and within each zone, monotypic conditions prevail]
"Lack" of Sago. By lack we mean no continuous, extended stands. However, we may have occasional stems here and there.
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