Introduction
The Truckee-Carson River System supplies water to the high-desert communities of northwestern Nevada through spring snowmelt originating as winter snowpack in the Sierra Nevada. Climate change impacts water management in the region (USGCRP, 2017) by altering the amount of snowpack that accumulates in the mountains (Mote, Hamlet, Clark, & Lettenmaier, 2005; Trujillo & Molotch, 2014), changing the type of winter precipitation that occurs (rain versus snow) (Knowles, Dettinger, & Cayan, 2006), and shifting the timing of snowmelt (Fritze, Stewart, & Pebesma, 2011; Regonda, Rajagopalan, Clark, & Pitlick 2005).
Thus, when we discuss climate change impacts in the region, attention is focused on changes in snowpack storage that directly impact water supply (Li, Wrzesien, Durand, Adam, & Lettenmaier, 2017). Referred to as snow drought, such conditions may be the result of either: 1) a period of abnormally low snowpack for the time of year, reflecting either below-normal cold-season precipitation (dry snow drought) or 2) a lack of snow accumulation despite near normal precipitation, usually when warm temperatures prevent precipitation from falling as snow or result in unusually early snowmelt (warm snow drought) (AMS, 2017; Harpold, Dettinger, & Rajagopal, 2017).
Earlier snowmelt runoff, for example, alters streamflow timing and reduces summer streamflow (Barnhart et al., 2016; Stewart, Cayan, & Dettinger, 2005). Earlier snowmelt reduces surface water supply, particularly during dry periods (Georgakakos et al., 2014), while also affecting groundwater recharge (Harpold, 2016; Jasechko et al., 2014). Warmer spring temperatures further compound dry periods by increasing evaporation from surface water reservoirs and lakes, diminishing soil moisture, and increasing evaporation of irrigated crops (Hatchett, Boyle, Putnam, & Bassett, 2015).
Recent 2012 to 2015 drought conditions experienced in the region remain unprecedented due to decreased snowpack accumulation enhanced by warmer winter temperatures (Belmecheri, Babst, Wahl, Stahle, & Trouet, 2016; Bond, Chronin, Freeland, & Mantua, 2015; Cayan et al., 2016; Cook, Ault, & Smerdon, 2015; Mote et al., 2016). The period 2012 to 2015 was the driest four-year period in California and the 29th driest in Nevada in a 122-year record (CNAP, 2017). Snowpack measured April 1 was three percent of normal in the Carson Basin and 13 percent of normal in the Truckee Basin (NRCS, 2015a), and coincided with record-high January through March temperatures (NOAA, 2015).
The year following (2016) was modestly wet, with April 1 snowpack conditions resembling near-normal snow water equivalence. However, warmer temperatures in April (e.g., 2 F to 4
F)accelerated snowmelt considerably (NRCS, 2016a; b; Nevada State Climate Office, 2016). New snow accumulation in the higher elevations at the end of April 2016, paired with unseasonably cooler temperatures in May, helped to stretch water supply and delay irrigation water demand. Yet by July, agricultural managers at the river system terminus (e.g., Newlands Project) still faced water supply shortages due to previous consecutive years of drought conditions (NOAA, 2017; NRCS, 2016c).
A collaborative research design recruits and uses local knowledge to aid researchers in understanding how local water managers are adapting to continued water supply variability (Klenk et al., 2015; Meadow et al., 2015; Parris et al., 2016). Collaborative research also strengthens local adaptive capacity in that it requires researchers and key stakeholders to learn together through information exchange (Ensor & Harvey, 2015; McGreavy et al., 2015). Collecting primary data from managers and including their input throughout the research program ensures that research results are useful for decision-making while also advancing applied climate science research.
The collaborative modeling research design implemented to assess drought resiliency in the Truckee-Carson River System relies on researchers’ continuous engagement with a Stakeholder Affiliate Group comprised of key local water managers (Singletary & Sterle, 2017; Singletary & Sterle, forthcoming 2018; Sterle & Singletary, 2017). Managers represent municipal, industrial, agricultural, environmental and regulatory water-use interests from the river system headwaters to terminus.
As part of the social learning process, interviews and focus groups provide a method of primary data collection to support information exchange. Focus groups served as a second round of primary data collection. The first round of primary data for this case study was collected during face-to-face interviews with 66 local water managers between March and August, 2015. These data allowed researchers to identify baseline water supply challenges during normal versus drought water years (Sterle & Singletary, 2017). During these interviews, managers described adaptation strategies, defined as adjustments or actions devised or taken in response to water supply variability due to decreasing or variable winter precipitation, warming temperatures and shifting seasonality (Moser & Boykoff, 2013). Additionally, managers described barriers that impede their ability to adapt, furthering researchers’ understanding of information needs across the river system.
Focus groups were conducted during the 2016 summer irrigation season with local managers to determine to what extent continued water supply variability in the Truckee-Carson River System challenged water management and the adaptation strategies managers were planning or implementing. The resulting focus group data furthered a systemwide understanding of how variable water supply, particularly during consecutive drought years, impacts diverse water-use communities that depend on a snow-fed, and highly regulated, river system.
This Extension Special Publication reports the results of the 2016 focus group discussions. It examines, during consecutive drought years, the local water supply challenges faced and subsequent strategies sought to adapt to variable conditions and any barriers encountered. This report does not instruct managers as to which adaptation strategies they should implement, but rather reports the adaptation strategies they identified and implementation challenges faced.
To download the complete special report use the link below.
