Monitoring Sediment and Water Quality in Clear Creek
The Clear Creek watershed in Eagle Valley lies along the eastern front of the Sierra Nevada near Carson City, Nevada. The upper portion of the watershed borders the Lake Tahoe basin. Clear Creek is a perennial stream with three main perennial branches and several small intermittent tributaries originating from springs and seeps. Clear Creek generally flows eastward along its approximate 12–mile length and discharges to the Carson River at an altitude of about 4,600 ft near the small community of Stewart. USGS currently operates and maintains a continuous streamflow gage on Clear Creek, about 3 miles upstream from the confluence.
The study area begins in the headwaters (altitude of about 9,200 ft) and extends to a reach near Fuji Park in Carson City (altitude of 4,765 ft). The 2.5 mi reach of Clear Creek between Fuji Park and the Carson River confluence in southern Carson City is outside the study area. The average main channel slope throughout the study area is about 380 ft/mi (17 percent slope); however, the higher elevation headwaters area has a slope of approximately 1,000 ft/mi, the midsection has a slope of approximately 308 ft/mi (6 percent slope), and where Clear Creek enters Eagle Valley, the slope is approximately 58 ft/mi (1 percent slope; Seiler and Wood, 2009, p. 17). The area of the drainage basin is about 20 square miles.
As a result of fires, extreme precipitation events, and human activities, some areas within the middle reach of the Clear Creek watershed have experienced severe erosion as evidenced by an incised stream channel and presence of sediments deposited into lower portions of the watershed. Construction of large commercial buildings and parking lots adjacent to, and near, the creek in its lower reaches may be affecting stream–water quality and sediment yield. Planned and future development in the mid–part of the watershed may also affect water quality and sediment loading. A planned residential community and a nearly completed golf course may increase urban runoff to Clear Creek. To provide winter access to private, State, Federal, and tribal lands in the basin, salt is applied to the main paved road (old U.S. Highway 50 and Highway 50), which, in places, closely parallels the stream. In the lower reach of Clear Creek, the stream may be affected by urban runoff and highway runoff.
An initial study by Seiler and Wood (2009), in cooperation with the Nevada Department of Transportation (NDOT), evaluated Clear Creek discharge, selected water–quality parameters, and suspended–sediment concentrations, loads, and yields, for water years 2004–07 from data collected at three sampling sites. Data were collected to establish a baseline in sediment and water chemistry for Clear Creek that can eventually be used to evaluate the impact of runoff and potential sediment transport related to U.S. Highway 50 and land use changes within the watershed. During this period, the annual suspended– sediment load in Clear Creek ranged from 100 to 1,456 tons. Since that time, data have continued to be collected (2010 – 2012) and the results of the continued sampling will be presented in a Scientific Investigations Report.
The objectives of this study are to build on what was learned from Seiler and Wood (2009) and serves as a continuation of the data collection and analyses of the Clear Creek discharge regime and associated water–quality and sediment concentrations and loads during water years 2010–12 by evaluating:
- long–term stream discharge,
- long–term sediment transport properties and potential changes in total sediment load over time, and
- concentrations of selected chemical constituents in Clear Creek.
For purposes of this study, Clear Creek has been subdivided into three reaches: Reach 1 covers approximately 2.5 stream miles in the upper part of the watershed. Reach 2 covers almost 6 stream miles in the middle of the watershed. Reach 3 covers approximately 1.5 stream miles of the lower reach of the watershed upstream of Highway 395 (adjacent to Fuji Park). The three sampling sites established along the 12 mile length of Clear Creek are each located at the terminus of each defined reach covering about 83 percent of the total length of the stream.
Data collected as part of this study will be evaluated in context with previously collected data. According to published information in Seiler and Wood (2009), data collected during and prior to 2007 preceded the development of a planned community and golf course near the center of the study area. Site 1, located at the terminus of the upstream segment, is intended to represent undeveloped conditions and there has been little to no development within this reach. Downstream from site 1, at sites 2 and 3, data collected from 2009 through 2012 were collected during the construction of the golf course and during the preparation of the land intended for the planned residential community. Samples collected as part of this effort will capture conditions in Clear Creek after the near completion of the golf course and during the construction of the residential area.
At each of the three sites, samples of water chemistry (major ions, trace elements, nutrients, DO, pH, specific conductance, and alkalinity) will be collected on a quarterly basis approximately coinciding with fall, winter, spring, and summer seasons. In addition to samples collected during routine visits, water–quality samples will be collected three times during spring runoff and up to four times within a given year during selected storm events. Major constituents include calcium, chloride, magnesium, potassium, sodium, and sulfate; trace constituents include, but are not limited to, arsenic, cadmium, chromium, nickel, uranium, and zinc. Nutrient samples will be analyzed for ammonium, nitrite, nitrate, total and dissolved organic nitrogen, orthophosphate, and total and dissolved phosphorus. Streamflow measurements will be made during each site visit. Samples will be collected using equal–discharge–increment (EDI) protocols according to published USGS guidelines.
Suspended–sediment samples will be collected about every 6 to 8 weeks at each site. Efforts will be made to coordinate between quarterly water quality and suspended sediment sampling. Additional suspended–sediment samples will be collected during high flow events and during the period of spring snowmelt to characterize suspended–sediment loading during flows carrying the greatest loads. These samples will also be collected using EDI protocols. Bedload samples will be collected upon observation of bed sediment movement.
Daily stream flow will continue to be monitored at the gaging station on Clear Creek near Carson City. The Data Collection Platform (DCP) at the gaging station will be monitored to provide USGS early warning of high flows and the ability to sample during storm events. In addition to the quarterly samples described above, an automatic sampler has been installed at the gaging station and will sample for suspended sediment during high flow events. Bedload samples will be collected during selected visits during high flow events, dependent on observed bedload movement. Initial samples of bed sediment will be collected and analyzed at the Test America Laboratories for total petroleum hydrocarbons (TPH). Data from these bed sediment samples will be used to evaluate past presence or absence of TPH in Clear Creek. Aqueous concentrations of TPH will be evaluated by quarterly deployment of three 15x16 cm semi–permeable membrane devices (SPMDs) over a period of a full year, followed by one–quarterly deployment for the remainder of the study.
Two additional Scientific Investigations Reports will be released covering data collection for the period of 2012–2016. The additional information on sediment yield and water quality in the Clear Creek watershed will assist in evaluating current and future changes in water chemistry and sediment transport in the watershed, which may be related to increased urbanization, wildfire, and implementation of best management practices.
Seiler, R.L., and Wood, J.L., 2009, Sediment Loads and Yield, and Selected Water–Quality parameters in Clear Creek, Carson City and Douglas County, Nevada, Water Years 2004–07: U.S. Geological Survey Scientific Investigations Report 2009–5005, 45 p.
Location: Carson River Basin, western Nevada
Start Date: 2010
End Date: 2016
Cooperator: Nevada Department of Transportation
USGS Nevada Water Science Center
2730 N. Deer Run Rd.
Carson City, NV 89701
phone: (775) 887–7692