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Lake Restoration/Management
Soil & Water Conservation Society of Metro Halifax (SWCSMH)
July 26, 2006
Contents:
Examples of common lake problems, impaired uses, and possible causes of the problem. (Olem & Flock. 1990)
Legend: XX= Problem shown definitely impairs use shown; X= Problem shown
may impair use shown
Impaired Use- Aesthetics:
- Common problems/Symptoms: Algae scum
- Possible causes of the problem- High nutrients
- Common problems/Symptoms: Weeds
- Possible causes of the problem- Shallowness, High nutrients, Sediment
- Common problems/Symptoms: Depth- X
- Common problems/Symptoms: User conflicts
- Possible causes of the problem- Motor Boat Noise, Debris
- Common problems/Symptoms: Taste & Odour
- Possible causes of the problem- High Nutrients, High Organics, Algae
Impaired Use- Fishing:
- Common problems/Symptoms: Weeds- X
- Common problems/Symptoms: Fish kills
- Possible causes of the problem- Toxins, No oxygen, High organics,
Sediment
- Common problems/Symptoms: Depth- X
- Common problems/Symptoms: User conflicts
- Possible causes of the problem- Motor Boating, Swimming
- Common problems/Symptoms: Taste & Odour- XX
Impaired Use- Swimming:
- Common problems/Symptoms: Algae scum- XX
- Common problems/Symptoms: Weeds- X
- Common problems/Symptoms: Depth- XX
- Common problems/Symptoms: User conflicts
- Possible causes of the problem- Motor Boating
- Common problems/Symptoms: Taste & Odour- XX
Impaired Use- Motor Boating:
- Common problems/Symptoms: Weeds- X
- Common problems/Symptoms: Depth- XX
- Common problems/Symptoms: User conflicts
- Possible causes of the problem- Swimming, Scuba Diving
Impaired Use- Sailing:
- Common problems/Symptoms: Weeds- X
- Common problems/Symptoms: Depth- XX
- Common problems/Symptoms: User conflicts
- Possible causes of the problem- Motor Boating, Swimming, Scuba Diving
Impaired Use- Water Supply:
- Common problems/Symptoms: Algae scum- X
- Common problems/Symptoms: Depth- XX
- Common problems/Symptoms: User conflicts
- Possible causes of the problem- Swimming, Motor Oils, Gas, Debris
- Common problems/Symptoms: Taste & Odour- XX
(Olem & Flock. 1990)
BEST MANAGEMENT PRACTICES (BMP)
- AGRICULTURE:
- Conservation Tillage
- Contour Farming
- Contour Stripcropping
- Integrated Pest Management
- Range and Pasture Management
- Crop Rotation
- Terraces
- Animal Waste Management
- Fertilizer Management
- Livestock Exclusion
- CONSTRUCTION:
- Nonvegetative Soil Stabilization
- Disturbed Area Limits
- Surface Roughening
- MULTICATEGORY:
- Streamside Management Zones
- Grassed Waterways
- Interception or Diversion Practices
- Streambank Stabilization
- Detention/Sedimentation Basins
- Vegetative Stabilization
- URBAN:
- Porous Pavements
- Flood Storage
- Street Cleaning
- SILVICULTURE:
- Ground Cover Maintenance
- Road and Skid Trail Management
- Riparian Zone Management
- Pesticide/Herbicide Management
Any discussions of in-lake technique effectiveness, except where
explicitly stated, always assume that loadings of nutrients, silt, and
organic matter to the lake have already been controlled. Most in-lake
procedures will be quickly overwhelmed by contin ued accumulation of these
substances. In-lake programs can complement watershed efforts; however,
such problems as algae, turbidity, and sedimentation may persist despite
load reductions or diversion projects unless an in-lake procedure is also
used.
Effectiveness, cost and chance of negative side effects associated with select watershed best management practices
Legend: E=Excellent; G=Good; F=Fair; P=Poor; U=Unknown
- AGRICULTURE:
- Conservation Tillage:
- Sediment: G-E
- Nitrogen: P
- Phosphorus: F-E
- Runoff: G-E
- Cost: F-G
- Chance of Negative Effects: F-G
- Contour Farming:
- Sediment: F-G
- Nitrogen: U
- Phosphorus: F
- Runoff: F-G
- Cost: G
- Chance of Negative Effects: P
- Contour Stripcropping:
- Sediment: G
- Nitrogen: U
- Phosphorus: F-G
- Runoff: G-E
- Cost: G
- Chance of Negative Effects: P
- Range and Pasture Management:
- Sediment: G
- Nitrogen: U
- Phosphorus: U
- Runoff: G
- Cost: G
- Chance of Negative Effects: P
- Crop Rotation:
- Sediment: G
- Nitrogen: F-G
- Phosphorus: F-G
- Runoff: G
- Cost: F-G
- Chance of Negative Effects: p
- Terraces:
- Sediment: G-E
- Nitrogen: U
- Phosphorus: U
- Runoff: F
- Cost: F-G
- Chance of Negative Effects: F
- Animal Waste Management:
- Sediment: N/A
- Nitrogen: G-E
- Phosphorus: G-E
- Runoff: N/A
- Cost: P
- Chance of Negative Effects: F
- URBAN:
- Porous Pavement:
- Sediment: F-G
- Nitrogen: F-G
- Phosphorus: F-G
- Runoff: G-E
- Cost: P-G
- Chance of Negative Effects: F
- Street Cleaning:
- Sediment: P
- Nitrogen: P
- Phosphorus: P
- Runoff: P
- Cost: P
- Chance of Negative Effects: U
- SILVICULTURE:
- Ground Cover Maintenance:
- Sediment: G
- Nitrogen: G
- Phosphorus: G
- Runoff: G
- Cost: G
- Chance of Negative Effects: P
- Road and Skid Trail Management:
- Sediment: G
- Nitrogen: U
- Phosphorus: U
- Runoff: U
- Cost: P
- Chance of Negative Effects: F
- CONSTRUCTION:
- Nonvegetative Soil Stabilization:
- Sediment: E
- Nitrogen: P
- Phosphorus: P
- Runoff: P-G
- Cost: F-G
- Chance of Negative Effects: F
- Surface Roughening:
- Sediment: G
- Nitrogen: U
- Phosphorus: U
- Runoff: G
- Cost: F
- Chance of Negative Effects: P
- MULTICATEGORY:
- Streamside Management Zones:
- Sediment: G-E
- Nitrogen: G-E
- Phosphorus: G-E
- Runoff: G-E
- Cost: G
- Chance of Negative Effects: F
- Grassed Waterways:
- Sediment: G-E
- Nitrogen: U
- Phosphorus: P-G
- Runoff: F-G
- Cost: F-G
- Chance of Negative Effects: P
- Interception or Diversion Practices:
- Sediment: F-G
- Nitrogen: F-G
- Phosphorus: F-G
- Runoff: P
- Cost: P-F
- Chance of Negative Effects: P
- Streambank Stabilization:
- Sediment:
- Nitrogen:
- Phosphorus:
- Runoff:
- Cost:
- Chance of Negative Effects:
- Detention/Sedimentation Basins:
- Sediment: G
- Nitrogen: U
- Phosphorus: U
- Runoff: P
- Cost: P-G
- Chance of Negative Effects: F
Hypothetical Lake In-Lake Management Evaluation Matrix
(Olem & Flock.1990)
Legend: E=Excellent G=Good F=Fair P=Poor
- Alum Treatment to Precipitate and Inactivate Phosphorus:
- Effectiveness: E
- Longevity: G
- Confidence: G
- ApplicabilityE:
- Potential negative impacts: F-G
- Capital Cost: G
- O & M Cost: G
- Dredging of Whole Lake:
- Effectiveness: P
- Longevity: E
- Confidence: E
- Applicability: P
- Potential negative impacts: F-G
- Capital Cost: P
- O & M Cost: E
- Dredging of Lake Inlet Areas:
- Effectiveness: E
- Longevity: E
- Confidence: E
- Applicability: E
- Potential negative impacts: G
- Capital Cost: F
- O & M Cost: E
- Dilution:
- Effectiveness: F
- Longevity: F
- Confidence: F
- Applicability: P
- Potential negative impacts: F
- Capital Cost: P
- O & M Cost: P
- Flushing/Artificial Circulation:
- Effectiveness: F
- Longevity: F
- Confidence: P
- Applicability: F
- Potential negative impacts: F
- Capital Cost: P
- O & M Cost: F-P
- Hypolimnetic Aeration:
- Effectiveness: F
- Longevity: F
- Confidence: F
- Applicability: F
- Potential negative impacts: F
- Capital Cost: P
- O & M Cost: F-P
- Sediment Oxidation:
- Effectiveness: G
- Longevity: G
- Confidence: P
- Applicability: F
- Potential negative impacts: G
- Capital Cost: F
- O & M Cost: G
- Addition of Algicides:
- Effectiveness: G
- Longevity: P
- Confidence: E
- Applicability: F
- Potential negative impacts: P
- Capital Cost: G
- O & M Cost: P
- Food Chain Manipulation:
- Effectiveness: G
- Longevity: Unknown
- Confidence: P
- Applicability: F
- Potential negative impacts: Unknown
- Capital Cost: E
- O & M Cost: E
- Hypolimnetic Withdrawal:
- Effectiveness: G
- Longevity: G
- Confidence: G
- Applicability: G
- Potential negative impacts: F-P
- Capital Cost: G
- O & M Cost: E
- Water Level Drawdown to Remove Weeds:
- Effectiveness: F
- Longevity: F
- Confidence: F
- Applicability: P
- Potential negative impacts: F-P
- Capital Cost: F
- O & M Cost: G
- Weed Harvesting:
- Effectiveness: G
- Longevity: P
- Confidence: G
- Applicability: G
- Potential negative impacts: F
- Capital Cost: F
- O & M Cost: P
- Biological Controls to Reduce Weeds:
- Effectiveness: G
- Longevity: G
- Confidence: F
- Applicability: G
- Potential negative impacts: F-P
- Capital Cost: G
- O & M Cost: G
- Addition of Herbicides:
- Effectiveness: G
- Longevity: P
- Confidence: G
- Applicability: F
- Potential negative impacts: P
- Capital Cost: G
- O & M Cost: P
(USEPA, 1988; Gersberg et al, 1983; Good et al, 1978; Hantzsche, 1985;
Hickok et al, 1977; Kadlec, 1978; Reuter et al, 1992; Verry et al, 1982;
Tennessee Valley Authority; Pope, 1981; Lakshman, 1978; Brown, 1985; Water
Environment Federation, 1989)
One outgrowth of clean water legislation has been to promote interest in
using natural and constructed wetlands. The scientific literature is
replete with evidence that wetlands have the ability effectively to
decrease levels of nutrients, suspended sedi ments, BOD, heavy metals and
even viruses from stormwater, as well as domestic wastewater in warm as
well as cold climates. Pollutant removal occurs through a combination of:
(1) physical-chemical mechanisms, including entrapment, sedimentation,
adsorpti on, precipitation and volatilization; and (2) biological
transformations such as bacterial denitrification, bacterial and algal
uptake and uptake by wetland vegetation.
- The aquatic treatment systems fall under three categories, viz.,
Natural Wetlands, Constructed Wetlands, and Aquatic Plant Systems.
- Natural Wetlands encompass marshes (grasses or forbs dominant), swamps
(characterized by trees and shrubs), or bogs (sedge/peat occurs).
- Constructed Wetlands are either free water surface systems (FWS) with
shallow water depths or subsurface flow systems (SFS) with water flowing
laterally through the sand or gravel.
- Aquatic Plant Systems are shallow ponds with floating or submerged
aquatic plants.
Adsorption and precipitation reactions in the soil are reported to be the
major mechanism of wastewater P removal by natural wetlands. In
constructed wetlands, some P can be permanently removed by harvesting
plants and sediment. Soluble inorganic P is r eadily immobilized in
inorganic soils by reactions with aluminium, iron, calcium, clays and
other minerals. Particulate P that flows into wetlands in association
with sediments or organic matter is primarily removed by sedimentation.
However, adsorption and precipitation do not represent a limitless sink
for P, and under conditions of long-term, heavy loading, it is possible to
saturate a wetland system and significantly reduce its efficiency as a
natural filter. Indeed, it has been reported that many wetlands have a
limited capacity to remove P relative to nitrogen. Nitrate removal in
wetlands occurs almost exclusively via denitrification.
The use of wetlands for secondary and tertiary wastewater treatment has
been extensively reported in the literature. Wetlands treatment of
stormwater has also been reported (Reuter et al, 1992; Verry et al,
1982; Brown, 1985). Results from a newly const ructed wetland to treat
stormwater in a cold climate region of California at Lake Tahoe (Reuter et
al, 1992) were encouraging.
Gravel-filled constructed wetlands (Lake Tahoe) provide a much greater
surface area for bacterial attachment than is possible in natural
wetlands, thereby enhancing the substratum to water volume contact ratio,
and hence need less land area than natural wetlands. Constructed
Wetlands are most suitable as mitigation for small development projects
where land is limited. These projects include golf courses that receive
fertilizers, small commercial facilities, small housing developments, etc.
They are gen erally limited in efficiency by the volume of water they can
retain (4-8 day retention). It may be unrealistic to rely on small
constructed wetlands to treat large urban areas.
(Olem & Flock. 1990)
Legend: E=Excellent; G=Good; H=High; F=Fair; P=Poor; L=Low; U=Unknown
Treatment (one application)
- Phosphorus Inactivation:
- Short-term effect- E
- Long-term effect- E
- Cost- G
- Chance of negative effects- L
- Dredging:
- Short-term effect- F
- Long-term effect- E
- Cost- P
- Chance of negative effects- F
- Dilution:
- Short-term effect- G
- Long-term effect- G
- Cost- F
- Chance of negative effects- L
- Flushing:
- Short-term effect- F
- Long-term effect- F
- Cost- F
- Chance of negative effects- L
- Artificial Circulation:
- Short-term effect- G
- Long-term effect- U
- Cost- G
- Chance of negative effects- F
- Hypolimnetic Aeration:
- Short-term effect- F
- Long-term effect- U
- Cost- G
- Chance of negative effects- F
- Sediment Oxidation:
- Short-term effect- G
- Long-term effect- E
- Cost- F
- Chance of negative effects- U
- Algicides:
- Short-term effect- G
- Long-term effect- P
- Cost- G
- Chance of negative effects- H
- Food Chain Manipulation:
- Short-term effect- U
- Long-term effect- U
- Cost- E
- Chance of negative effects- U
- Rough Fish Removal:
- Short-term effect- G
- Long-term effect- P
- Cost- E
- Chance of negative effects- U
- Hypolimnetic Withdrawal:
- Short-term effect- G
- Long-term effect- G
- Cost- G
- Chance of negative effects- F
Comparison of Lake Restoration and Management Techniques for Control of Nuisance Aquatic Weeds
(Olem & Flock. 1990)
Legend: E=Excellent; F=Fair; G=Good; P=Poor; H=High; L=Low;
*The introduction of grass carp is prohibited by law in several states and
provinces
Treatment (one application)
- Sediment Removal:
- Short-term effect- E
- Long-term effect- E
- Cost- P
- Chance of negative effects- F
- Drawdown:
- Short-term effect- G
- Long-term effect- F
- Cost- E
- Chance of negative effects- F
- Sediment Covers:
- Short-term effect- E
- Long-term effect- F
- Cost- P
- Chance of negative effects- L
- *Grass Carp:
- Short-term effect- P
- Long-term effect- E
- Cost- E
- Chance of negative effects- F
- Insects:
- Short-term effect- P
- Long-term effect- G
- Cost- E
- Chance of negative effects- L
- Harvesting:
- Short-term effect- E
- Long-term effect- F
- Cost- F
- Chance of negative effects- F
- Herbicides:
- Short-term effect- E
- Long-term effect- P
- Cost- F
- Chance of negative effects- H
(Benndorf & Miersch 1991; Northcote 1988; DeMelo et al 1992; Shapiro et al 1984; Carpenter ed. 1988)
Lake biomanipulation theory is based on the prediction that increased
piscivore abundance will result in decreased planktivore abundance,
increased zooplankton abundance, and increased zooplankton grazing
pressure leading to reductions in phytoplankton ab undance and improved
water clarity. Water quality is dependent to a great extent on structure
and function of food webs in aquatic ecosystems. Food webs are controlled
by resource limitation ("bottom-up") and by predation ("top-down").
Undoubtedly, so lar energy and nutrient inputs and dynamics of an
ecosystem set its overall level of production, so to that extent the
control may be envisaged as bottom-up, but within those limits, some of
the "coarse-tuning" and much of the "fine-tuning" of structure a nd
function in the system results from the complexity of top-down processes.
If the hypothesis of the "biomanipulation-efficiency threshold of the
P-loading" should be confirmed by further investigations, important
consequences for water quality management would emerge.
Comparison of top-down effects in 14 whole-lake biomanipulation
studies (+ = effect observed; - = effect not observed; ? = no data). The
results are presented in the following format:
[a = Effect explained by external P-load reduction
b = Shallow lakes with macrophytes
c = High flushing rate of the water]
Haugatjern:
- Estimated total P-load (g P/m2.yr)= 0.1
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +
- Potentially dense blooms of blue-greens= -
- Decrease of in-lake total phosphorus= +
L. Michigan:
- Estimated total P-load (g P/m2.yr)=0.11
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +
- Potentially dense blooms of blue-greens= -
- Decrease of in-lake total phosphorus= +(a)
Stockelidsvatten:
- Estimated total P-load (g P/m2.yr)=0.3-0.5
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +
- Potentially dense blooms of blue-greens= -
- Decrease of in-lake total phosphorus= +
L. Trummen:
- Estimated total P-load (g P/m2.yr)=low
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +
- Potentially dense blooms of blue-greens= -
- Decrease of in-lake total phosphorus= +
Tuesday L.:
- Estimated total P-load (g P/m2.yr)=low
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +
- Potentially dense blooms of blue-greens= -
- Decrease of in-lake total phosphorus= ?
Round Lake:
- Estimated total P-load (g P/m2.yr)=0.6-0.7
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +
- Potentially dense blooms of blue-greens= -
- Decrease of in-lake total phosphorus= +
Lago di Annone:
- Estimated total P-load (g P/m2.yr)=0.5-0.8
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= ?
- Reduction of phytoplankton biomass= +
- Potentially dense blooms of blue-greens= ?
- Decrease of in-lake total phosphorus= ?
Loch Loso:
- Estimated total P-load (g P/m2.yr)=0.6-0.8
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +
- Potentially dense blooms of blue-greens= +
- Decrease of in-lake total phosphorus= ?
Grafenhain:
- Estimated total P-load (g P/m2.yr)=0.66
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= -
- Potentially dense blooms of blue-greens= -
- Decrease of in-lake total phosphorus= ?
Wirth Lake(b):
- Estimated total P-load (g P/m2.yr)=0.6-1.0
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= -
- Potentially dense blooms of blue-greens= +
- Decrease of in-lake total phosphorus= -
L. of Isles(b):
- Estimated total P-load (g P/m2.yr)=2.0
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +(b)
- Potentially dense blooms of blue-greens= -(b)
- Decrease of in-lake total phosphorus= -
Broads Brundall:
- Estimated total P-load (g P/m2.yr)=3.6
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +(b)
- Potentially dense blooms of blue-greens= -(b)
- Decrease of in-lake total phosphorus= -
Elbe backwaters:
- Estimated total P-load (g P/m2.yr)=13.0
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= +(c)
- Potentially dense blooms of blue-greens= -(c)
- Decrease of in-lake total phosphorus= -
Bautzen Reservoir:
- Estimated total P-load (g P/m2.yr)=7.7-17.5
- Dominance of large herbivorous zooplankton= +
- Increase in Secchi depth= +
- Reduction of phytoplankton biomass= -
- Potentially dense blooms of blue-greens= +
- Decrease of in-lake total phosphorus= -
A high reliability of biomanipulation (i.e. top-down control of
eutrophication) could then only be expected if the phosphorus loading a
priori is below the threshold (oligotrophic and mesotrophic lakes), or if
the phosphorus loading exceeding the thresho ld (eutrophic and
hypertrophic lakes) will be reduced by other methods, or if the intensity
of bottom-up mechanisms will be strongly controlled by light.
On the other hand, some investigators have pointed out that apparent
biomanipulation successes may not have been caused by the cascading
effects of zooplankton feeding on phytoplankton, but resulted from several
of alternate food-web interactions. Are t hese examples merely atypical
anomalies or rather do they reflect a systematic disharmony or
incompetence in the biomanipulation theory to adequately address the
majority of natural phenomena ? (DeMelo et al, 1992)
(Peterson 1981)
Freshwater lake sediment removal is usually undertaken to deepen a lake
thereby increasing it's volume to enhance fish producion, to remove
nutrient rich sediment, to remove toxic or hazardous material, or to
reduce the abundance of rooted aquatic plants. Review of more than 60
projects and examination of 5 case histories (Lake Trummen, Sweden; Lake
Herman, South Dakota; Wisconsin Spring Ponds; Steinmetz Lake, New York;
and Lilly Lake, Wisconsin), reveals that the first three objectives are
usually met t hrough sediment removal. The technique is recommended for
deepening and for reducing phosphorus release from sediment. Sediment
removal to control toxic materials is possible with minimal environmental
impact when proper equipment is used, but it may be extremely expensive.
Dredging will remove rooted aquatic plants, however, their re-encroachment
rate will be depth, sediment texture, and sediment nutrient dependent.
Total phosphorus content of sediments in selected lakes in North
America
- Sammamish, WA:
- Total P (mg/g dry wt)= 2-5
- Lower St. Regis, NY:
- Total P (mg/g dry wt)= 0.5-1.4
- Huron:
- Total P (mg/g dry wt)= ~1-~2
- Ontario:
- Total P (mg/g dry wt)= ~1.2-~3.0
- Erie:
- Total P (mg/g dry wt)= ~1-~2
- Erie:
- Total P (mg/g dry wt)= 0.19-2.9
- Core Depth= top 3cm from 48 sites
- Monona, WI:
- Total P (mg/g dry wt)= ~1-~2.2
- Washington, WA:
- Total P (mg/g dry wt)= ~1->6
- Shagawa, MN:
- Total P (mg/g dry wt)= 1-5
(OECD 1982)
Practically all phosphorus sources can be made to bypass a lake through a
circular canal, and it was most effectively demonstrated in the now
classic restoration case of Lake Washington.
(OECD 1982)
A siphon called an Olszewski pipe is used to discharge nutrient rich water
from the hypolimnium. This process reduces the thickness of the
tropholytic layer and increases that of the trophogenic one, reduces the
nutrient and toxic content of the hypolimnium and eliminates some of the
water that is low in oxygen or lacking it completely. Considerable
improvement in the reduction of the trophic response was obtained in
several lakes such as Mauensee, Wilersee, and Piburgersee in Europe. This
method is restricted to relatively small, deep lakes with a topography
suitable for the application of a siphon.
(Fast et al 1976; Fast & Lorenzen 1976; Fast 1973; Lorenzen & Fast 1977; Olem & Flock 1990)
Hypolimnetic aeration/oxygenation is an effective means of improving
domestic and industrial water quality, satisfying downstream water release
standards and creating suitable habitat for yearlong survival of cold
water fish. It may be achieved by pure oxygen injection, or air
injection. With air injection and downstream released, care must be taken
not to supersaturate the water with nitrogen gas. Hypolimnetic aeration
is the only known method of creating suitable cold water habitat in most
warm eutro phic lakes. This system of aeration can result in adequate
oxygen values throughout the lake without intolerable increases in
hypolimnetic temperatures. Oxygen can be added to the hypolimnium without
greatly heating it, or mixing it with epilimnetic or metalimnetic water.
Another use is to eliminate taste and color problems by precipitating iron
and manganese. Hypolimnetic aeration may promote some control of algae by
a type of phosphorus inactivation procedure under high oxygen, high iron
conditions. A classic case history is the St. Paul water supply.
Hypolimnetic aerators need a large hypolimnium to work properly;
consequently, any use of these aerators in shallow lakes and reservoirs
should be done cautiously, if at all.
(Welch 1981)
Dilution/flushing has been documented as an effective restoration
technique for Moses and Green Lakes in Washington State. The dilution
water added in both lakes was low in nitrogen and phosphorus content
relative to the lake or normal input water. Flus hing rates were about
ten times normal during the spring-summer periods in Moses Lake and three
times normal on an annual basis in Green Lake. Improvement in quality
(nutrients, algae, and transparency) was on the order of 50% in Moses Lake
and even grea ter in Green Lake. Quality improvement may occur from
physical effects of washout and instability if only high nutrient water is
available.
(Olem & Flock 1990; Lorenzen & Fast 1977; Vandermeulen 1992)
Artificial circulation eliminates thermal stratification or prevents its
formation, through the injection of compressed air into lake water from a
pipe or ceramic diffuser at the lake's bottom.
Algal blooms may be controlled, possibly through one or more of these
processes:
- Mixing to the lake's bottom will increase a cell's time in darkness,
leading to reduced net photosynthesis.
- Introduction of dissolved oxygen to the lake's bottom may inhibit
phosphorus release from sediments.
- Rapid contact of water with the atmosphere, as well as the
introduction of carbon dioxide-rich water during the initial period of
mixing, can lower pH, leading to a shift from blue-greens to less noxious
green algae.
- When zooplankton are mixed to the lake's bottom, they are less
vulnerable to sight-feeding fish, resulting in the increase of consumption
of algal cells by the zooplankton.
(OECD 1982; Olem & Flock 1990)
Iron, calcium and aluminum have salts that can combine with (or sorb)
inorganic phosphorus or remove phosphorus-containing particulate matter
from the water column as part of a floc. This method has been applied in
the reservoirs in the Netherlands. Tot al phosphorus concentrations and
algal biomass were successfully reduced in the Braakman and the Grote Rug
Reservoirs. The disadvantage of this method is that some of the
phosphorus precipitated is not bound permanently in the sediments and thus
it could contribute to a later internal loading.
Aluminum is most often chosen because phosphorus binds tightly to its
salts over a wide range of ecological conditions, including low or zero
dissolved oxygen. In practice, aluminum sulfate (alum) or sodium
aluminate (for soft water lakes) is added to t he water, and pinpoint,
colloidal aggregates of aluminum hydroxide are formed. In addition, if
enough alum is added, a layer of 1 to 2 inches of aluminum hydroxide will
cover the sediments and significantly retard the release of phosphorus
into the water column as an "internal load".
Phosphorus inactivation has been highly effective and long-lasting in
thermally stratified natural lakes, especially where an adequate dose has
been given to the sediments and where sufficient diversion of nutrient
incomes has occurred. These treatments have been made to the more common
smaller lakes and farm ponds as well.
(Babin et al, 1989; Murphy & Pepas, 1990; Murphy et al, 1988; Murphy et al, 1991; Prepas et al, 1990)
While lime treatment has been extensively used to mitigate acidification
effects, several studies of calcium carbonate precipitation led to the
hypothesis that the addition of lime to lakes can also reduce
eutrophication. Although biological reactions mu st influence phosphorus
biogeochemistry, the effect of lime treatment on phosphorus
biogeochemistry can be easily explained via apatite formation.
The generally accepted model for apatite formation is that phosphorus
initially adsorbs to calcite and then a surface rearrangement produces
phosphate heteronuclei that ultimately form the stable mineral apatite.
If the surface application of calcium hy droxide was repeated for a number
of years, the titration should exceed an end point, phosphorus and calcium
should not redissolve, and phosphorus could be converted into apatite.
Lime has been added to several lakes and dugouts in Western Canada
(Frisken, Figure Eight, Andorra, Beaumaris, Valencia, Halfmoon, Gour,
Monnette, Desrosier, Frey, Fedora, Pederson, Sullivan, Schreger, Limno) to
improve water quality. These hardwater la kes are eutrophic due to high
natural, agricultural, or urban loadings of phosphorus. Source control of
phosphorus loadings would be extremely difficult at all sites. Most of
the lakes are primarily used for recreation but the dugouts have been used
for human and agricultural water supplies. In two of the study sites,
Figure Eight Lake and Frisken Lake, most of the sediment iron is converted
into pyrite. These lakes have little reactive iron and presumably
phosphorus biogeochemistry is not controlled by iron reactions.
(Olem & Flock 1990)
Exposing sediments to prolonged freezing (2-4 weeks) and drying results in
permanent damage to certain rooted plant species, but the technique is
species-specific:
- DECREASE
- Coontail
- Brazilian elodea
- Milfoil
- Southern naiad
- Yellow Water Lily
- Water Lily
- Robbin's Pondweed
- INCREASE
- Alligator Weed
- Hydrilla
- Bushy Pondweed
- VARIABLE
- WaterHyacinth
- Common Elodea
- Cattail
(Olem & Flock. 1990)
Sediment covering materials stop plant growth by the fact that rooted
plants require light and cannot grow through physical barriers. These can
be used in small areas such as dock spaces and swimming beaches only due
to the high costs.
- MATERIAL-Black Polyethylene
- Specific Gravity=0.95
- Application Difficulty-High
- Gas Permeability-Impermeable
- Comments-Poor choice of materials, easily dislodged: "balloons"
- MATERIAL-Polypropyl (Typar)
- Specific Gravity=0.90
- Application Difficulty-Low
- Gas Permeability-Permeable
- Comments-Effective
- MATERIAL-Fiberglass PVC (Aquascreen)
- Specific Gravity=2.54
- Application Difficulty-Low
- Gas Permeability-Permeable
- Comments-Effective
- MATERIAL-Nylon (Dartek)
- Specific Gravity=1.0
- Application Difficulty-Moderate
- Gas Permeability-Impermeable
- Comments-Effective if vented
- MATERIAL-Burlap
- Specific Gravity=1.0
- Application Difficulty-Moderate
- Gas Permeability-Permeable
- Comments-Effective up to one season: rots
- MATERIAL-Nylon- Silicone
- Specific Gravity=1.5
- Application Difficulty-?
- Gas Permeability-Impermeable
- Comments-Must be installed by dealer
(OECD 1982; Olem & Flock 1990)
Conventional waste water treatment is intended to reduce the organic
matter in waste water and not to control phosphorus. The purely
biological and mechanical process can remove 20-25% of phosphorus
initially present, while modified, activated sludge pla nts can remove
about 55% of phosphorus present in some special cases. Thus, phosphorus
removal efficiency of conventional waste water treatment is very limited
and usually not adequate to meet the requirements of a phosphorus program.
In addition, durin g the summer, waste water discharges may dominate
stream flow during dry periods when total flow is lower than usual, and
water cannot hold as much dissolved oxygen as it does during the cooler
periods of the year. Phosphorus removal efficiency in existi ng treatment
plants can be improved by the application of a chemical precipitation
process to the effluent.
Phosphorus from waste water can be effectively eliminated with a
precipitation process. In this process aluminum or iron salts or lime are
added to the waste water which form insoluble compounds with the
phosphates. Different kinds of precipitation pro cesses may be employed,
such as pre-precipitation, simultaneous precipitation and
post-precipitation in combination with the biological process. The most
comprehensive experience of phosphorus precipitation has been obtained in
Sweden, and by early 1978, more than 600 municipal waste water treatment
plants were operated with combined biological and chemical treatment.
It has been shown that where there is proper design and the use of
suitable pH-values in the precipitation step, and no significant process
disturbances, the following effluent concentrations of total phosphorus
could be expected:
- pre- or simultaneous precipitations: 0.5- 0.8mgP/l;
- post-precipitation: 0.2- 0.4mgP/l;
- post-precipitation followed by filtration or simultaneous precipita
tion followed by contact filtration: 0.15- 0.3mgP/l.
(Ryding & Rast 1989)
- Aeration/Destratification:
- Arbuckle & Ham's lakes, Oklahoma, USA; Farm pond, Oregon, USA;
Fischkaltersee, Germany; Klopeiner See, Kraiger See, Piburger See,
Worthersee, Ossiacher See, Millstädter See & Weieusee, Austria; Larson &
Mirror lakes, Wis., USA; Occoquan rese rvoir, Virginia, USA; Spruce Run
reservoir, NJ., USA; and various other lakes and reservoirs in North
America, Europe & Asia.
- Biomanipulation:
- Bautzen reservoir, Germany; Farm ponds, Nebraska, USA; Lake Trummen,
Lake Bysjön & Lilla Stockelidsvatten, Sweden; and various other lakes and
reservoirs in Argentina, Guyana, India, Poland, Sudan, Sweden, USA, Russia
& Zimbabwe.
- Covering bottom sediments:
- Cox Hollow Lake & Marion Millpond, Wisconsin, USA; and several other
lakes in USA & Canada.
- Dilution/Flushing:
- Green & Moses lakes, Washington, USA; Snake lake, Wisconsin, USA.
- Harvesting of macrophytes:
- Laguna lake, Philippines; Lake Sallie, Minnesota, USA; and several
other lakes and reservoirs in Michigan, Minnesota & Wisconsin, USA.
- Hypolimnetic injection of nutrient effluents:
- Precambrian lake, Canada.
- Lake drawdown:
- Lake Apopka, Florida, USA; and various other lakes and reservoirs in
USA.
- Nutrient inactivation:
- Beerenplaat, The Netherlands; East Twin & West Twin lakes, Ohio, USA;
Horseshoe lake, Wisconsin, USA; Medical lake, Washington, USA; Stone
lake, Michigan, USA; Lake Jabel, Suesser See, Talsperre, Haltern, Tegeler
See & Wahnbachtalsperre, Germany; an d various other lakes in Europe,
Australia, & North America.
- Sediment removal (Dredging):
- Beverinsee, Germany; Lilly lake, Wisconsin, USA; Lake Herman, South
Dakota, USA; Lake Trummen, Lake Trehörningen & Lake Trummen, Sweden;
Steinmetz lake, New York, USA; Lake Stubenberg, Austria.
- Phosphorus removal at rivermouth (Pre-reservs):
- Wahnbach reservoir, & various pre-dams, Germany.
- Wastewater diversion/Seepage trenches:
- Lake Fuschl, Lake Ossiacher, Worthersee, Ossiacher See. Millstadter
See, & Weiensee, Austria; Lake Gjersjoen, Norway; Kerspetalsperre,
Schliersee, Tegernsee, & Stechlinsee, Germany; lower Madison lakes, Lake
Waubesa, & Lake Wegonsa, Wisconsin, USA; Ma uensee, Switzerland; Lake
McIlwaine, Zimbabwe; Lake Minnetonka, Minnesota, USA; Lake Norrviken &
Lake Ųyesjön, Sweden; Lake Sammamish, & Lake Washington, Washington, USA;
Lake Vesijarn, Finland; and various other lakes in Austria & Sweden.
- Wastewater treatment for phosphorus removal (including phosphate
detergent restrictions):
- Lake Asvalltjarn, Lake Boren, Lake Ekoln, Görväln Bay, Lake Ringsjön,
Stockholm Archipelago, & Lake Vättern, Sweden; Lake Burrinjuck,
Australia; Lake Constance, & Greifensee, Germany; Finger Lakes, & Lower
St. Regis, New York, USA; Gravenhurst Bay, K ootenay Lake, & Little Otter
Lake, Canada; Haley Pond, USA; Lake Mjųsa, Norway; Saginaw Bay,
Michigan, USA; Shagawa Lake, Minnesota, USA; Walensee & Zurichsee,
Switzerland; and various other lakes in Sweden.
- Multiple control measures:
- Lake Balaton, Austria & Hungary; North American Great Lakes, USA &
Canada.
cf. Lake Restoration (Summary of in-lake methodology for both culturally and naturally eutrophic lakes, the Canadian experience)
Lafayette Reservoir, California (Lorenzen
et al In Corvallis Env. Res. Lab. 1979):
- Drainage area= 830 ac., mostly undeveloped park and recreational area.
Lake area= 125 ac., Mean depth= 30 ft., stratifies April-Nov. Lake was
eutrophic principally from nutrient rich sediments. The project includes
hypolimnetic aeration to provide a su itable habitat for coldwater
sportfish and alum treatment for nutrient inactivation to limit algal
growth. Alum was applied to the surface water ( 70 tons) during the
summer and to the hypolimnium ( 130 tons) in the fall. The aerator was to
be operated during summer only.
Stone Lake, Michigan (Theis & DePinto.
1976):
- Surface area= 60 ha., Depths= 18 m (max) & 6 m (mean), Drainage area=
176 ha (urban= 128 ha, forest= 40 ha, agricultural= 6.4 ha). Stone Lake
is a typical natural seepage lake with accelerated eutrophic conditions.
During periods of dissolved oxygen dep letion in the hypolimnium, large
amounts of phosphorus and nitrogen are released in the overlying water. A
cyclic pattern of phytoplankton was observed during the summer, with green
algae followed by nitrogen-fixing blue-greens followed again by green al
gae with available forms of nitrogen regulating the cycle.
- Particulate materials, especially certain clays and fly ash, were
shown to be potentially effective lake restoration tools for controlling
biogeochemical cycling of pollutants from eutrophic sediments. In most
cases a 2 to 5 cm layer of material was nee ded to control phosphate
release. Supplemental chemical addition, such as lime or alum, enhances
initial phosphate removal from the overlying water. Available data
indicates potentially harmful effects from other water soluble extracts of
fly ash, parti cularly sulfur (as SO3-2) and various heavy metals. Short
term extremes of pH may also affect biota unfavorably.
Lake Aeration in several Wisconsin Lakes
(Wirth. 1988):
- Lake aeration in Wisconsin is done primarily to reduce winter fish
kill. Only one lake operated an aeration system year-round, and that was
for water quality. Compressed Air Systems in 20 lakes (Big Eau Pleine,
Sinissippi, Fox, Thunder, Buckskin, Otter, Horsehead, Emily, Largon,
Mayflower, Goose, Silver, Williams, Coon, Patrick, Fenners, Long,
Jacqueline, Virginia, Joyce), Compressed Surface Spray Systems in 6 lakes
(White, Red Cedar, Hope, Black Otter, Kinney, Beechwood), Pump and Cascade
system in 3 l akes (Rib, Kettle Moraine, Little Elkhart), and Mechanical
Impeller and Aspirator system in 1 lake (North Spirit) were utilized.
Lake Vikvatn, Norway (Biomanipulation)
(Koksvik & Reinertsen. 1991):
- Surface area= 0.46 km2, Depths= 15 m (max) & 7.6 m (mean), surrounded
by deciduous woods, heaths and bare mountains. Utilized for fish farming
since 1980. Visible algal blooms led to the rotenone treatment in June
1984, as an experiment in order to impr ove the water quality. The
experiment shows how removal of planktivore fish, in this case mainly
three-spined sticklebacks, may change ecosystem structure and function,
and underlines the significance of top-down control in lake ecosystems.
It is assume d that the change to larger individual size in the daphnid
populations was the approximate reason for the improved water quality.
The superiority of large individuals in food gathering that implies the
ability to utilize a greater size variety of food pa rticles seems to be
of major importance in preventing blue-green algae from developing.
- Tot N (uµg)l):
- Period: Feb 1983- June 1984
- Mean SD(±)= 418(±)41
- Range= 330-465
- N= 8
- Period: Nov 1984- July 1985
- Mean SD(±)= 221(±)42
- Range= 148-280
- N= 8
- Tot P (ug/l):
- Period: Feb 1983- June 1984
- Mean SD(±)= 38(±)12
- Range= 21-50
- N= 11
- Period: Nov 1984 - July 1985
- Mean SD(±)= 13(±)2
- Range= 9-15
- N= 6
- Secchi Disc transparency (m):
- Period: June - Nov 1983
- Mean SD(±)= 2.1(±)0.4
- Range= 1.4-2.7
- N= 12
- Period: June- Nov 1984
- Mean SD(±)= 2.6(±)0.5
- Range= 2.0-3.6
- N= 10
- Period: June- Oct 1985
- Mean SD(±)= 3.4(±)0.4
- Range= 2.8-4.0
- N= 7
- Period: June - Oct 1986
- Mean SD(±)= 3.1(±)0.4
- Range= 2.6-3.7
- N= 5
Lake Eola, Orlando, Florida (Wanielista et al.
1982):
- Watershed= 59 ha. Separate storm sewers. (33.7 ha commercial and 25.3
ha residential). Lake area= 11 ha, Mean depth= 3 m. Parkland= 4.5 ha.
Impervious= 49.3 ha. Lake was eutrophic. Implementation steps
recommended: Stormwater management, littoral z one planting, and
coagulant coverage of bottom muds. Stormwater management to be
implemented by diversion/percolation of parking lot runoff and limited
street runoff (24 ha), and another 27.0 ha to be managed by diversion for
filtration before discharge to the lake.
Mirror and Shadow Lakes, Waupaca, Wisconsin
(Garrison & Knauer 1981):
- Mirror and Shadow Lakes, small seepage lakes, had experienced cultural
eutrophication as a result of storm water drainage. Storm sewers were
diverted from the lakes in 1976 and in 1978 aluminum sulfate was applied
to enhance the recovery rate by reducing internal phosphorus loading from
the sediments. Mirror Lake was artificially circulated to prevent low
winter oxygen concentrations and increase spring oxygen concentrations.
Storm sewer diversion reduced external phosphorus loading from 58-65 % for
bo th lakes while the aluminum sulfate application reduced inlake
phosphorus concentrations from 90 mg/m3 and 55 mg/m3 in Mirror and Shadow
Lakes respectively to 20-25 mg/m3.
- Maximum Depth=
- Mirror Lake- 13.1m
- Shadow Lake- 11.6m
- Mean Depth=
- Mirror Lake- 7.8m
- Shadow Lake- 5.3m
- Surface Area=
- Mirror Lake- 5.1ha
- Shadow Lake- 17.1ha
- Watershed (Prediversion)=
- Mirror Lake- 32.2ha
- Shadow Lake- 76.9ha
- Watershed (Postdiversion)=
- Mirror Lake- 13.1ha
- Shadow Lake- 56.7ha
Lake Erie (OECD. 1982): (Estimated costs of
phosphorus reduction alternatives, after PLUARG, 1978)
- Urban point sources:
- Remedial measure options: Reduction of municipal sewage treatment
plant effluent concentration: a) 1.0 mg/l to 0.5mg/l:
- Estimated annual incremented unit costs $/kg phosphorus
reduction= 8.0
- Remedial measure options: Reduction of municipal sewage treatment
plant effluent concentration: a) b) 0.5mg/l to 0.3 mg/l:
- Estimated annual incremented unit costs $/kg phosphorus reduction=
95.5
- Rural nonpoint sources:
- Remedial measure options: Level 1: Sound management on all
agricultural lands, avoiding excess fertilization, reducing soil erosion
(10% phosphorus reduction)
- Estimated annual incremented unit costs $/kg phosphorus reduction=
- Remedial measure options: Level 2: Level 1 measures, plus buffer
strips, strip cropping, improved municipal drainage practices, etc.,
depending on region (25% reduction in phosphorus losses on soils requiring
treatment):
- Estimated annual incremented unit costs $/kg phosphorus reduction=
64.3
- Remedial measure options: Level 3: Level 2 measures at greater in
tensity of effort (to achieve 40% reduction in phosphorus losses on soils
needing treatment):
- Estimated annual incremented unit costs $/kg phosphorus reduction=
174.0
- Urban nonpoint sources:
- Remedial measure options: Level 1: Programme of pollutant
reduction at source:
- Estimated annual incremented unit costs $/kg phosphorus reduction=
82.0
- Remedial measure options: Level 2: Level 1 measures, plus
detention/sedimentation:
- Estimated annual incremented unit costs $/kg phosphorus reduction=
156.9
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