Reports
Sediment Quality Assessment of Herrington Lake, Garrett County, Maryland
2022, Gillmor, A., Van Ryswick, S., Sylvia, E.R., Connallon, C., and Nicholson, B.
File Reports, Coastal and Estuarine Geology, File Report 20-05
Executive Summary
Maryland Geological Survey, in conjunction with other Maryland Department of Natural Resources programs, including Tidewater Ecosystem Assessment (TEA) and Fishing and Boating Services, was asked to perform sediment quality assessments of state-owned lakes in Maryland. The goal is to provide surficial sediment data for each lake to determine general sediment physical and chemical characteristics as a pre-assessment for potential future lake sediment dredging. Physical and chemical analysis of the sediments from each lake will pose as a baseline for the lake’s sediment data. The sediment data will be incorporated into other study aspects, including fish populations, water quality, and submerged aquatic vegetation (SAV) abundance and distribution in order to generate overall lake health and status.
This report focuses on Herrington Lake in Garrett County, Maryland. The lake is 53 acres and is located within Herrington Manor State Park. Fifteen surficial sediment samples were collected throughout the lake and coordinates were stored using Real-Time Kinematic Global Positioning System (RTK GPS). Sediment at each site was described and sampled for analysis. Analysis includes physical properties, including bulk density and grain size, and elemental analysis.
The majority of the samples collected are fine-grained sediments, with an average textural content of 10% sand, 42% silt and 45% clay. Seven samples classify as silty-clay, five samples classify as clayey-silt and three samples classify as sand-silt-clay.
The shallow sediments collected from Herrington Lake were found to have fairly high averages of total carbon (C) content (5.1% by dry weight), nitrogen (N) content of 0.5%, phosphorus (P) content of 0.7% and a sulfur (S) content of 0.1%. C, N and S concentrations were highly inter-correlated at Herrington Lake, which we suspect may be due to the abundant fresh organic material in the sediments.
The elemental concentrations of 15 surficial sediments followed similar spatial patterns to each other when plotted by station, to correlate generally with clay content. This was true for Al, Fe, K, Na, Mg, although Ca was slightly different. Many trace elements also had profiles that were generally similar to each other. These include Zn, Cr and Ni, Cu and Pb in a muted way, and As and Cr in an amplified way. When compared relative to two eco-toxicological screening levels for freshwater sediments, all metals of concern were above the more conservative lowest effect level (LEL) and Fe and Mn were above the higher severe effect level (SEL) in some samples. Since these concentrations represent more than that which is environmentally available, eco-toxicological harm is not anticipated. When compared to relative crustal abundance via the use of Fe-normalized enrichment factors, the elements. Cd, Hf, Pb, Sb and Zn were elevated. However, these elements are often encountered in high concentrations in clay-rich sedimentary rocks and the sediments derived from them.
The 15 collected samples throughout Herrington Lake were similar to sediments of other lakes nearby, including Deep Creek Lake. No abnormalities were found in regard to the physical or chemical properties of the bottom sediments of Herrington Lake.
