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Shallow Hydrogeologic Framework of the Tully Valley Mudboil Area, Onondaga County, New York

Scientific Investigations Report 2026-5129
Prepared in cooperation with the New York State Department of Environmental Conservation, U.S. Environmental Protection Agency, Onondaga Nation, Onondaga Environmental Institute, and Central New York Regional Planning and Development Board
By: , , , , , and 
https://doi.org/10.3133/sir20265129

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Abstract

Mudboils have been documented in the Tully Valley in southern Onondaga County, New York, since the late 1890s. Sediment-laden water from the mudboils flows into Onondaga Creek, which empties into Onondaga Lake at Syracuse 15 miles to the north. Turbidity from the mudboils has degraded the water quality of Onondaga Creek despite a series of mitigation efforts that began in the early 1990s. Turbidity mitigation actions presently (2025) being considered include creek relocation and offline sediment settling. In support of these proposed actions during 2021–23, the U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation, U.S. Environmental Protection Agency, Onondaga Nation, Onondaga Environmental Institute, and Central New York Regional Planning and Development Board, collected and analyzed geologic, hydrologic, geophysical, and geotechnical data to characterize the shallow hydrogeology along four proposed creek-relocation paths and in the proposed offline settling basin area.

The investigation indicated that the four proposed creek-relocation paths, two east of Onondaga Creek and two west of Onondaga Creek, are underlain by sediments including muck, alluvium, mudboil deposits, alluvial-fan sand and gravel, and lacustrine fines. The proposed excavations would penetrate partially to fully saturated conditions: generally, the water table is shallow near the creek and deep on the alluvial fans. The shallowest excavation, about 5 feet below land surface, would be near the creek and primarily in alluvium, and the deepest excavation, as much as 30 feet below land surface, would be in the alluvial-fan deposits. Brackish waters would be penetrated by proposed channel excavations on the eastern side of Onondaga Creek in an area downgradient from a potentially leaking historical salt-exploration borehole and near the main mudboil area. Excavation in these areas likely would provide a continuous source of brackish groundwater to the relocated creek. Proposed channel excavations of muck, soft to very soft lacustrine fines, and mudboil-type sediments in mudboil and suspected mudboil areas would pose an excavation and slope stability challenge and would have the greatest potential to create new mudboils. Proposed channel excavations below the water table on the Rattlesnake Gulf and Rainbow Creek alluvial fans would intercept groundwater and make the constructed streambank susceptible to seepage-induced slope instability. The substantial water-level fluctuation in the sediments of both alluvial fans would aggravate the stability condition. In addition, excavation on the Rattlesnake Gulf alluvial fan would have the potential to affect water-supply springs at the toe of the fan.

The proposed offline settling basin area is in the northern part of the Rattlesnake Gulf alluvial fan. Natural and man-made diversions of Rattlesnake Gulf have resulted in saturated conditions in the general area of the proposed basin. The proposed offline settling basin would be excavated in, and berms would be constructed on, alluvial-fan deposits and lacustrine fines. In the proposed basin area, the alluvial deposits overlying the lacustrine fines are less than 10 feet thick. Excavation, berm construction, and loading of the saturated, soft to very soft lacustrine fines may be problematic and require soil strengthening.

Suggested Citation

Williams, J.H., Terry, N.C., Kappel, W.M., Heisig, P.M., Glas, R.L., and Woda, J.C., 2026, Shallow hydrogeologic framework of the Tully Valley mudboil area, Onondaga County, New York: U.S. Geological Survey Scientific Investigations Report 2026–5129, 58 p., https://doi.org/10.3133/sir20265129.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Geologic Setting
  • Mudboils
  • Previous Investigations of the Mudboil Area
  • Data Sources and Methods
  • Surficial Geology
  • Precipitation
  • Groundwater Levels and Specific Conductance
  • Shallow Hydrogeologic Framework of Proposed Creek Relocation Paths and Offline Basin Settling Area
  • Summary
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Shallow hydrogeologic framework of the Tully Valley mudboil area, Onondaga County, New York
Series title Scientific Investigations Report
Series number 2026-5129
DOI 10.3133/sir20265129
Publication Date April 29, 2026
Year Published 2026
Language English
Publisher U.S. Geological Survey
Publisher location Reston VA
Contributing office(s) New York Water Science Center
Description Report: ix, 58 p.; Data Release
Country United States
State New York
County Onondaga County
Other Geospatial Tully Valley Mudboil Area
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Additional publication details