New Germany Lake Sediments New Germany Lake Sediment Accumulation Survey New Germany State Park 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 Sediments Agenda • 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 13 14 15 10 1112 Core Sample Location Map • Aerial Imagery is from 2007 • Yellow diamonds are location of cores collected for this study 7A 78 9 6 21 3 5 4 • Core 16 was collected downstream to identify/verify historical soil character New Germany Lake Sediments Core Collection Activities New Germany Lake Sediments Sediment Class Water Sediment Type Content Soft Mud 65% Sand-Silt-Clay Lake Sediments Firm Mud 53% Silty-Clay Comments Sediment Depth Gassy; lots of Organic material Gassy; firm mud, slightly sandy 0-0.4 Feet 0.4-1.8 Feet Organic Firm Mud 35% 23-32% Sand-Silt-Clay Silty Sand Root structures; slighty sandy mud 1.8-2.3 Feet Firm mud, slightly sandy Historical Soil Valley Deposit 2.3-3.05 Feet Alluvium 17% gravelly muddy Sand Soil Profile 10% muddy sandy Gravel Core #3 – South End of Lake Near Current Beach Very firm; pebbles, lots of rocks, color 3.05-3.7 Feet change Significant color change, more red, 3.7-5.1 Feet lots of ¾”rocks, multiple large (1.5”) rocks, very dry, mottled New Germany Lake Sediments Lake Water Surface 13 14 15 10 -5 Feet 7A 78 9 -10 Feet 6 21 5 4 3 DAM 1112 New Germany Lake Sediments Sediment Surface 13 14 15 -1.5 Feet 10 -3 Feet 7A 78 9 -4.5 Feet 6 21 -6 Feet 5 4 3 DAM 1112 New Germany Lake Sediments Lead / Zinc Downcore Trends Enrichment Factor based on Al Zn Pb 1.00 5.00 Core 9 0 1 Core 4 Zn Enrichment Factor Pb 2 3 4 5 0.00 2.00 3.00 4.00 0.00 0 30 4.00 5.00 6.00 1.0 Foot 1.0 Foot Depth (cm) 20 40 50 60 1.0 Foot Depth (cm) 60 Core depth (cm) 3.00 40 10 30 2.00 20 20 0 1.00 0 10 6 Zn Pb Core 11 Enrichment Factor based on Al 2.0 Feet 3.0 Feet 100 140 80 90 80 120 70 40 2.0 Feet 3.0 Feet 160 50 60 70 80 2.0 Feet 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. 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 Current Dam Swauger Dam Distances measured from multiple maps / images from the Marsh shoreline to Twin Oaks Road 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 =0.5m/yr 39 years 238-202 meters =0.5m/yr 69 years 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. 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 Management Options • 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 New Germany Lake Sediments • Ranger Mary Ironside • Mironside@dnr.state.md.us • Dnr.maryland.gov/publiclands/western/newgermany.asp