Depth of cinder deposits and water-storage capacity at Cinder Lake, Coconino County, Arizona

Open-File Report 2012-1018
Prepared in cooperation with Coconino County, Arizona, and the U.S. Forest Service
By: , and 



The 2010 Schultz fire northeast of Flagstaff, Arizona, burned more than 15,000 acres on the east side of San Francisco Mountain from June 20 to July 3. As a result, several drainages in the burn area are now more susceptible to increased frequency and volume of runoff, and downstream areas are more susceptible to flooding. Resultant flooding in areas downgradient of the burn has resulted in extensive damage to private lands and residences, municipal water lines, and roads. Coconino County, which encompasses Flagstaff, has responded by deepening and expanding a system of roadside ditches to move flood water away from communities and into an area of open U.S. Forest Service lands, known as Cinder Lake, where rapid infiltration can occur. Water that has been recently channeled into the Cinder Lake area has infiltrated into the volcanic cinders and could eventually migrate to the deep regional groundwater-flow system that underlies the area. How much water can potentially be diverted into Cinder Lake is unknown, and Coconino County is interested in determining how much storage is available. The U.S. Geological Survey conducted geophysical surveys and drilled four boreholes to determine the depth of the cinder beds and their potential for water storage capacity. Results from the geophysical surveys and boreholes indicate that interbedded cinders and alluvial deposits are underlain by basalt at about 30 feet below land surface. An average total porosity for the upper 30 feet of deposits was calculated at 43 percent for an area of 300 acres surrounding the boreholes, which yields a total potential subsurface storage for Cinder Lake of about 4,000 acre-feet. Ongoing monitoring of storage change in the Cinder Lake area was initiated using a network of gravity stations.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Depth of cinder deposits and water-storage capacity at Cinder Lake, Coconino County, Arizona
Series title Open-File Report
Series number 2012-1018
DOI 10.3133/ofr20121018
Year Published 2012
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Arizona Water Science Center
Description iv; 20 p.
Country United States
State Arizona
County Coconino County
City Flagstaff
Other Geospatial Cinder Lake
Datum North American Datum 1983
Projection Universal Transverse Mercator Projection Zone 11 North
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details