Experimental Halophyte Growth in Saline Environments

Alexes Garrett, Laurel Saito, Sydney Athey, Nicole Goehring, Paul Verburg, Louis Provencher

ABSTRACT
Salinization of soil and water can pose a serious threat for irrigated agricultural lands in arid and semi-arid regions because high concentrations of salt can negatively impact crop production, and consequently, the agricultural economy. Halophytes are highly salt-tolerant plants that may provide a viable option for cultivation in saline areas, enabling economic production from previously unproductive land. Many halophytes can be used for human consumption, forage for livestock, or biofuel production. These plants may also remediate saline soils by taking up salt from the soil, thereby improving conditions for conventional crop production. This project looked at growth of two halophytic crops, AC Saltlander green wheatgrass (Elymus hoffmannii) and Rainbow quinoa (Chenopodium quinoa var. rainbow) under different salt stresses in a greenhouse experiment. We cultivated the crops in a greenhouse with crossed saline soil (2, 4, 6, 8, and 12 dS/m) and irrigation (1, 2, 4, and 6 dS/m) treatments. We measured plant height approximately bi-weekly until harvest. A subset of harvested biomass, roots and soil subsamples were analyzed for nutrient and salt content. Quinoa and AC Saltlander aboveground biomass were larger for soil salinities greater than 2 dS/m, with maximum measured biomass after harvest of more than 5 g for quinoa, and more than 12 g for AC Saltlander. Quinoa height was greatest on most dates for soil salinity of 4 dS/m. There was a significant relationship between increased soil salinity and Cl content of quinoa plant tissues, roots, and soil at harvest, but irrigation salinity had no significant effects on analyzed quinoa variables. AC Saltlander root biomass decreased with increasing soil salinity, but had greatest root biomass at the 2 and 6 dS/m irrigation salinities (the smallest and greatest irrigation salinity treatments). AC Saltlander aboveground biomass chemistry (i.e., Ca, Na, and Cl) responded significantly to differences in soil chemistry. Similarly, AC Saltlander aboveground biomass Ca, Na, S, and Cl was significantly affected by irrigation salinity. Overall, both halophytes germinated, grew, and produced seeds in the greenhouse experiment on saline Nevada soils, so they may be options for alternative crops on marginal lands in Nevada with moderately saline irrigation water.

Keywords: salinity, quinoa, greenhouse
Citation: Garrett, A., Saito, L., Athey,S., Goehring, N., Verburg, P., and L. Provencher, 2020, Experimental Halophyte Growth in Saline Environments. Journal of the Nevada Water Resources Association, Winter 2020, p 5-28.
DOI: 10.22542/jnwra/2020/1/1. Copyright 2020 Nevada Water Resources Association.

Estimates of pit-lake evaporation and its potential effects on groundwater interactions with the Humboldt River

David E. Prudic

ABSTRACT
The Humboldt River, in northern Nevada supplies water mostly for irrigation of nearby croplands. Groundwater pumping both near and distant from the river has increased over the past 50 years. The primary use of groundwater is for irrigation of croplands but it is also an important source for municipalities, mining and other industries. Large gold deposits that require dewatering were discovered in the mountains of the central part of the drainage basin in the 1970’s and 1980’s. Much of the water pumped to dewater the mines is recharged back to groundwater in the valleys or is released to the Humboldt River or one of its tributaries. Of concern is the long-term loss of groundwater from pit-lake evaporation and how those losses could affect groundwater interactions with the Humboldt River once mine operations cease.

Flows in the Humboldt River are mostly dependent on snowmelt runoff from the mountains, particularly from mountains in the drainage area upstream of the Palisade gaging station. The mean flow increases with drainage area between the gaging stations upstream of Elko and at Palisade, whereas the mean flow decreases downstream of the Palisade gaging station. Much of the decrease in mean flow downstream of Palisade is caused by: (1) minimal additional contributions from runoff and groundwater flow; (2) spreading of water to native pastures on the floodplain; and (3) infiltration of river water into its associated alluvium. During low-flow periods, particularly during periods of drought, the Humboldt River between Battle Mountain and Comus gaging stations often has flows less than 1 cubic foot per second (cfs) even before there was any mine dewatering.

Estimated groundwater loss to evaporation for the five largest pit lakes in the drainage area between the Palisade and Comus gaging stations is about 5,400 acre-feet per year (afy) (7.6 cfs or five times less than the estimated net annual evaporation loss from the Rye Patch and the Pitt-Taylor Reservoirs upstream of Lovelock, Nevada. The groundwater loss to three of the pit lakes (Goldstrike Mine, Cortez operations, and Twin Creeks Mine) is unlikely to affect river flow because even prior to mine dewatering, groundwater flow from the low-lying mountains was lost to evapotranspiration near the base of the alluvial fans and did not contribute flow to the river.

The Lone Tree Mine ceased dewatering in December 2006 and since then a lake has formed in the pit. The floodplain of the Humboldt River in the reach between Battle Mountain and Comus is underlain by a layer of blue clay at shallow depth. Between 2007 and 2019, the net mean annual streamflow loss between Palisade and Comus is nearly the same as during a period of Groundwater evaporation from the eventual pit-lake at the Gold Quarry Mine is estimated at 740 afy (about 1 cfs) and could perhaps decrease the gain in the Humboldt River upstream of Palisade. How much of a decrease is uncertain because some of it could be lost to evapotranspiration at the edge of the floodplain prior to reaching the river. Even if the groundwater loss from the pit lake at Gold Quarry Mine were to reduce the gain of river flow between Carlin and Palisade, the loss would be too little to measure accurately.

Keywords: Pit lake, Evaporation, Groundwater, Humboldt River
Citation: Prudic, D. 2020, Estimates of pit-lake evaporation and its potential effects on groundwater interactions with the Humboldt River. Journal of the Nevada Water Resources Association, Winter 2020, p 29-47.
DOI: 10.22542/jnwra/2020/1/2. Copyright 2020 Nevada Water Resources Association.

Mapping indicators of groundwater dependent ecosystems in Nevada: Important resources for a water-limited state

Laurel Saito, Sarah Byer, Kevin Badik, Ken Mcgwire, Louis Provencher, Blake Minor

ABSTRACT
Groundwater dependent ecosystems (GDEs) rely on groundwater for all or part of their water needs, and provide benefits to plants, wildlife and people. Almost half of endemic species in Nevada are associated with GDEs. To increase our understanding of groundwater needs for GDEs we 1) created a spatial database to identify the location and extent of GDEs in Nevada; 2) developed a story map to share data from the database to increase awareness about GDEs among the general public; and 3) conducted an assessment of GDE condition for areas previously mapped at high resolution. We found that at least 10% of Nevada is classified as having an indicator of groundwater dependence, and over two-thirds of Nevada’s hydrographic areas contained all 5 types of indicators of GDEs (i.e., phreatophyte communities; wetlands; springs; lakes and playas; and rivers and streams). Of the GDEs in 11 landscapes in Nevada, GDEs in montane riparian systems were the most ecologically departed from reference, mostly due to non-native plant species. Our next steps involve using the database to assess stressors and threats to GDEs to help us develop and prioritize strategies for protecting GDEs for people and nature.
Keywords: phreatophytes, springs, wetlands, ecological departure
Citation: Saito, L., Byer,S., Badik, K., Mcgwire, K., Provencher,L., and B. Minor, 2020, Mapping indicators of groundwater dependent ecosystems in Nevada: Important resources for a water-limited state. Journal of the Nevada Water Resources Association, Winter 2020, p 48-72.
DOI: 10.22542/jnwra/2020/1/3. Copyright 2020 Nevada Water Resources Association. 49