new germany lake sediments new germany state park new germany lake sediment accumulation survey
TRANSCRIPT
New Germany Lake Sediments
New Germany State Park
New Germany Lake
Sediment Accumulation Survey
New Germany Lake Sediments
Purpose• DNR has a dual mandate to protect our
natural resources and provide recreational use of the lake at New Germany State Park
• Scientific collection of data establishes the foundation for the development of a Lake Management Plan
• Interests and concerns of park visitors and neighbors are a vital component of the Plan – Many thanks to the Friends of New Germany for pursuing the issue and actively participating in the process
New Germany Lake SedimentsAgenda
• Sediment Sampling (Cores)– Collection and Analysis Procedures– Historical Sediment – Accumulated Sediment
• Sediment Chemistry and Pollutants• Headwater Marsh Changes• Sediment Nutrients• Submerged Aquatic Vegetation Control• Management Options
New Germany Lake Sediments
New Germany Lake Timeline• Colonial Period – 9-15 foot channelized stream (Poplar Lick Run)
• 1837-1847 – Swauger Mill Dam was constructed at the same site as the current dam. This created a lake of approximately 9 acres in size. The dam was about 2 feet lower than the current dam.
• 1933-1935 – The current earthen dam with a concrete spillway was constructed. This new dam impounded the existing ~13 acres.
• 2008 – DNR Engineering & Construction performed maintenance on the concrete spillway, pedestrian bridge and drainage pipe.
• 2008 – DNR initiated the current study
New Germany Lake Sediments
Historical Markers of Sediment Levels
New Germany Lake Sediments
Core Sample Location Map
• Aerial Imagery is from 2007
• Yellow diamonds are location of cores collected for this study
• Core 16 was collected downstream to identify/verify historical soil character
123
456
77A8 9
101112
1314
15
New Germany Lake Sediments
Core Collection Activities
New Germany Lake SedimentsSediment Class Water
ContentSediment Type Comments Sediment
DepthSoft Mud 65% Sand-Silt-Clay Gassy; lots of
Organic material0-0.4 Feet
Firm Mud 53% Silty-Clay Gassy; firm mud, slightly sandy
0.4-1.8 Feet
Organic 35% Sand-Silt-Clay Root structures; slighty sandy mud
1.8-2.3 Feet
Firm Mud 23-32% Silty Sand Firm mud, slightly sandy
2.3-3.05 Feet
Alluvium 17% gravelly muddy Sand Very firm; pebbles, lots of rocks, color change
3.05-3.7 Feet
Soil Profile 10% muddy sandy Gravel Significant color change, more red, lots of ¾”rocks, multiple large (1.5”) rocks, very dry, mottled
3.7-5.1 Feet
Core #3 – South End of Lake Near Current Beach
Lake S
ed
imen
tsH
isto
rical S
oil
Valley
Dep
osi
t
New Germany Lake Sediments
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
C ore N um ber
4
3
2
1
0
De
pth
-- M
ete
rs f
rom
La
ke S
urf
ace
LegendSoft M ud
Firm M ud
O rganic Layer
C oarse M ateria l
Soil S tructure
W ater
123
456
77A8 9
101112
1314
15
DAM
-10 Feet
-5 Feet
Lake Water Surface
New Germany Lake Sediments
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
C ore N um ber
2
1.6
1.2
0.8
0.4
0
De
pth
--
Me
ters
from
La
ke B
ott
om
LegendSoft M ud
Firm M ud
O rganic Layer
C oarse M ateria l
Soil S tructure
123
456
77A8 9
101112
1314
15
DAM-6 Feet
-3 Feet
Sediment Surface
-1.5 Feet
-4.5 Feet
New Germany Lake Sediments
Lead / Zinc Downcore TrendsCore 4
0
10
20
30
40
50
60
70
80
0 1 2 3 4 5 6
Enrichment Factor
Cor
e de
pth
(cm
)
Zn
Pb
Core 9
0
10
20
30
40
50
60
70
80
90
0.00 1.00 2.00 3.00 4.00 5.00
Enrichment Factor based on Al
Dep
th (
cm)
ZnPb
Core 11
0
20
40
60
80
100
120
140
160
0.00 1.00 2.00 3.00 4.00 5.00 6.00
Enrichment Factor based on Al
Dep
th (
cm)
ZnPb
Lead and Zinc atmospheric and sediment concentrations increased in the early 1900s due to coal-powered factories, power generation, and the automobile.
The increase of Lead and Zinc concentrations in the uppermost sediments imply that the sediments shallower than 0.5-1 feet are more recent than 1900, and the sediments deeper than 0.5-1 feet are older than 1900.
1.0 Foot
2.0 Feet
1.0 Foot
1.0 Foot
2.0 Feet
2.0 Feet
3.0 Feet
3.0 Feet
New Germany Lake Sediments
Total Sediment Accumulation within Current Shoreline
Section Distance from Dam [Feet]
Average Accumulated Sediment [Feet]
South 0-410 2.65 [2.20-3.05]
Middle 410-1000 2.23 [1.84-3.01]
North 1000-1738 2.89 [1.84-3.81]
The average accumulated sediment thickness is 2.6 feet.
– 76% of all existing sediment in the lake was deposited in the first 60+ years of the lake’s history (1840-1900)
– 24% of all existing sediment in the lake accumulated in the last 108 years (1900-2008).
New Germany Lake Sediments
Chemical Analysis of Sediment
• 30 samples throughout the lake and at different sediment depths were analyzed for their elemental composition.– No significant elemental enrichments were detected.
• Three Samples (Core #s 1,11,15) were analyzed for semi-volatile organic pollutants and pesticides.– No pesticides or semi-volatile organic pollutants were
detected.
New Germany Lake Sediments
• The Wetland is an Important Environmental Feature of New Germany Lake.
– Sediment Trap
– Nutrient Sink
– Natural Habitat
New Germany Lake Sediments
Headwaters Marsh Changes
• Aerial Imagery is from 2007
• Blue line is shoreline from 1946 USGS Topographical Map
New Germany Lake Sediments
Headwaters Marsh Changes
Year Document Distance Measured (Meters)
1899 USGS Topo 330
1904 USGS Topo 342
1938 USGS Topo 349
1938 Imagery 202
1944 USGS Topo 207
1962 Imagery 211
1995 Imagery 238
2007 Imagery 238
349-330 meters
39 years=0.5m/yr
238-202 meters
69 years=0.5m/yr
Distances measured from multiple maps / images from the Marsh shoreline to Twin Oaks Road
Maps and Imagery show that the New Germany Lake Headwaters Marsh Shoreline has been growing at a rate of 0.5 meters per year (1.6 ft per year) since its establishment.
Cu
rren
t D
am
Sw
au
ger
Dam
New Germany Lake Sediments
Surface Sediment
– 8 samples collected in April 2010
– Elemental Analysis showed the same as Core Samples (no significant enrichments)
– Nutrient Analysis shows slightly enriched levels of Nitrogen.
New Germany Lake Sediments
Historic data on the composition and growth of the SAV population in New Germany Lake is not available.
Experience with deeper mountain lakes indicates that SAVs are found at water depths greater than the original water depths of New Germany Lake.
There is no reason to believe that the decrease in lake depth caused by sediment deposition has increased the SAV growth.
New Germany Lake Sediments
• SAV Control Options:
– Aquatic Herbicides– Biological Control Agents– Mechanical Harvesting– Winter Draw Down (Root Freezing)
New Germany Lake Sediments
Summary• Sediment Accumulation
Over the course of its ~170 year history, New Germany Lake has accumulated a maximum of 1.8 to 3.8 feet of sediment thickness throughout the majority of the lake, with most sediment accumulating in the northern portion of the lake. Environmental indicators show that a majority of this accumulation (76%) occurred before the early 1900s. Sediments that have accumulated since 1900 range in depth from 3-5 inches.
• Headwaters Marsh Growth
The delta formed in the headwaters of the lake has shown a consistent history of growth at 1.6 feet/year.
• Sediment Chemistry
No forms of sediment pollution were identified. Slightly elevated levels of Nitrogen were detected in the surface sediments.
• Submerged Aquatic Vegetation
SAV Growth has increased as the lake matured. The population currently inhabiting the lake includes native species that enhance aquatic habitat.
New Germany Lake Sediments
• Periodically monitor incoming sediment and marsh growth to determine if rates of deposition or growth have changed.
• Continue regular control program for Submerged Aquatic Vegetation (SAV) – This would not affect sedimentation rate but would reduce extent of SAV beds.
• Remove accumulated sediment from the lake or selected portions (includes dewatering facility) – Cost estimates are between 2-5 million dollars. Lake would be closed for a year or more.
• Remove accumulated sediment from upper end of lake – Removal of the existing natural wetland would result in significant ecological impacts and involve complex wetland permitting and mitigation issues.
• Explore management options to slow the current rate of growth in the headwaters marsh
Management Options
New Germany Lake Sediments
• Ranger Mary Ironside• [email protected]
• Dnr.maryland.gov/publiclands/western/newgermany.asp