A Re-evaluation of the Trophic State of Mountain Lake, Virginia, USA

Cawley, Jon C.; Parker, Barry; Beaty, Myron H.

doi:10.1080/02705060.1999.9663711

Cited by 3 publications

(3 citation statements)

References 8 publications

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“…It is worth reiterating that the lake itself does not occur in karst or limestone terrain, and the usual lake alkalinity of 2.9–10 mg/L, hardness of 12.4–34.0 mg/L, and pH ranges of 5.8–6.8 have remained consistently low (Roth and Neff, ; Obeng‐Asamoa and Parker, ; Parson and Parker, ; Beaty and Parker, ; Cawley et al ., ). The conditions of low alkalinity, low hardness, and circumneutral pH all indicate a poor buffering capacity for the lake water at the high‐stand.…”

Section: Discussionmentioning

confidence: 97%

“…Schultz et al . () suggested that the unit may contain limestone lenses and interbeds, although neither groundwater nor lake water have historically exhibited carbonate chemistry within the basin (Roth and Neff, ; Obeng‐Asamoa and Parker, ; Parson and Parker, ; Beaty and Parker, ; Cawley et al ., ). Roningen (), and Roningen and Burbey () found slightly higher calcium bicarbonate in wells in the Orem shales near the lodge.…”

Section: Previous Workmentioning

confidence: 97%

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Subsurface erosion, scarp retreat, and sedimentation at Mountain Lake, Virginia, USA: groundwater geomorphology in a flow‐through lake with subsurface drainage

Cawley

Irwin

2018

Earth Surf Processes Landf

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The complete natural drainage in 2008, 2011, and 2012 of Mountain Lake in Giles County, Virginia, allowed detailed observations of the only natural lake basin in the southern Appalachian Mountains. Here we use these observations to support geomorphic analysis and develop a model of basin evolution, which may advance the understanding of rare flow‐through lakes with subsurface drainage elsewhere. Key features included (a) an angle‐of‐repose slope with a smoothly concave planform across the entire 260 m width of the north end of the basin, (b) an arc of steep‐sided depressions along the deep northern margin of the basin floor, and (c) an abrupt transition between colluvial and finer‐grained sedimentary deposits on the floor. Our geomorphic analysis suggests that subsurface erosion has enabled long‐term northward scarp retreat in the basin by removing water and sediment. Mountain Lake formed on the northern limb of a breached anticline along the Eastern Continental Divide, where strong‐over‐weak stratigraphy and a small watershed have enabled the basin to evolve generally as follows. (1) Pond Drain, a first‐order tributary of the New River, incised north‐dipping sandstones and underlying shales on the northern limb of the anticline. The valley floor subsequently accumulated meters to tens of meters of mostly late Pleistocene colluvial fill. (2) Subsurface drainage developed likely along the contact between the sandstones and shales, facilitated by pre‐existing fractures. (3) Ongoing subsurface erosion has progressively undermined the sandstone, causing scarp retreat along the northern margin of the basin while a surface stream intermittently incised the shallow southern end. Sedimentary deposits indicate that only the deeper northern portion of the basin is usually flooded under Holocene conditions. Our basin evolution model suggests slow development of the basin over hundreds of thousands of years rather than sudden damming by a catastrophic landslide. Copyright © 2018 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 97%

Section: Previous Workmentioning

confidence: 97%

Subsurface erosion, scarp retreat, and sedimentation at Mountain Lake, Virginia, USA: groundwater geomorphology in a flow‐through lake with subsurface drainage

Cawley

Irwin

2018

Earth Surf Processes Landf

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“…Further, sediment P content on average is nearly twice as high downstream of more‐developed subwatersheds (Table 2), suggesting that P availability and algal production are linked. Because P and silica are limiting nutrients for algal growth, algal production (specifically diatoms) should increase as P and BSi input to the lake increase (Cawley et al, 1999). DeMaster et al (1996) suggest that preservation efficiencies of BSi and P differ in sediments, and in the present study a direct correlation between the concentrations of these nutrients was not found (Table 1).…”

Section: Discussionmentioning

confidence: 99%

Trophic Transition in a Lake on the Virginia Coastal Plain

Pensa

Chambers

2004

J of Env Quality

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To examine possible connections between lake trophic status and runoff from surrounding subwatersheds, we determined patterns of sediment and nutrient deposition in a hypereutrophic, 16-ha impoundment on the Virginia coastal plain. Spatial survey of nutrients in surface sediments documented a strong correlation between total P and extractable Fe (r2 = 0.53). Elevated biogenic silica concentrations up to 0.25% by weight were measured in sections of the lake receiving perennial stream discharge. Sediment C to N ratios were > 20 in those same sections, suggesting a large allochthonous contribution to organic matter deposition. Sediment cores 0.9 to 2.3 m in length, representing 70 years of deposition, were analyzed to develop vertical profiles of changes in sediment and nutrient deposition in deltas downstream from two more-developed and three less-developed subwatersheds (with 49 and 9% commercial and residential development, respectively). The average sediment weight percent +/- standard deviation of biogenic silica (0.027 +/- 0.037 vs. 0.009 +/- 0.006%) and total P (0.040 +/- 0.025 vs. 0.024 +/- 0.019%) was significantly higher downstream of more-developed subwatersheds. Using elevated P loadings and biogenic silica deposition as proxies for algal production, transition of the lake to its current hypereutrophic state appears to have occurred in the last 70 yr. Changes in trophic status as revealed by sediment analysis of this small lake on the Virginia coastal plain reflect a common pattern of eutrophication observed for the entire Chesapeake Bay drainage basin. Analysis of sediments from stream deltas appears to be a reasonable strategy for identifying and targeting subwatershed areas needing better management of nutrient runoff that otherwise would lead to eutrophication of downstream waters.

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An Inexpensive, Diver-Assisted Percussion Coring Device

Cawley

Parker

2001

Journal of Sedimentary Research

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A Re-evaluation of the Trophic State of Mountain Lake, Virginia, USA

Cited by 3 publications

References 8 publications

Subsurface erosion, scarp retreat, and sedimentation at Mountain Lake, Virginia, USA: groundwater geomorphology in a flow‐through lake with subsurface drainage

Subsurface erosion, scarp retreat, and sedimentation at Mountain Lake, Virginia, USA: groundwater geomorphology in a flow‐through lake with subsurface drainage

Trophic Transition in a Lake on the Virginia Coastal Plain

An Inexpensive, Diver-Assisted Percussion Coring Device

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