Yesterday we published a water trivia quiz to ring in the new water year. Today we bring you answers. For each right answer, have a drink of water—you deserve it! (Answer to bonus question: the water year runs from Oct. 1 to Sept. 30, which is the period when precipitation totals are measured.)
- What could bring the biggest reduction in water use for a family in a single-family home? B: Removing a lawn would bring the highest water savings. Outdoor landscaping accounts for roughly half of all urban water use, and lawn is the thirstiest piece of that equation, especially in the hotter, dryer parts of the state. Replacing lawn with native plants can reduce water use by up to 60%. But this can be a costly change for households to make.
Second best would be replacing an old toilet. Toilet flushing accounts for nearly a quarter of water use in the average home. Switching to a high-efficiency 1.28 gallon model can save more than 6,789 gallons per year if you started with a 5 gallon model, and about 4,000 if you had a 3.5 gallon one. Replacing a leaking toilet will bring even greater savings.
The showerhead is next. Bathing accounts for about 17 percent of household water use, and the US EPA Water Sense program estimates that switching from a standard 2.5 gallon-per-minute showerhead to a 2 gallon-per-minute one can save 2,900 gallons per year (and a significant amount of energy from lower water heating as well).
- What was California’s per-capita water use in 2015? B: 130 gallons per day in 2015 (the fourth year of the latest drought). That’s down from 232 gallons per day in 1995. On average, inland residents used more. The reasons: outdoor watering and a hotter climate (their average was 168 gallons per person per day), while coastal residents used just 119 gallons per day.
- What causes toxic algal blooms? D: The growing problem of toxic algal blooms is an “all of the above” problem. A combination of nutrient-rich runoff from farms, discharges of treated sewage and urban runoff, and the drought’s warmer water temperatures and reduced river flows, caused numerous algal blooms in our waterways this year.
- How much surface water did Central Valley farms receive in 2015 compared to a year with normal rainfall? C: In 2015, surface water deliveries to Central Valley farmers were about half those of a normal year. About half a million acres were fallowed in both 2014 and 2015, costing the farm economy nearly $2 billion, and as many as 10,000 full- and part-time farm jobs. Groundwater pumping replaced about 70 percent of the lost surface water, which worsened the problem of overdrafted groundwater basins in some places.
- How was California’s energy supply affected by the drought? D: All of the above. A drop in urban water use brought significant energy savings statewide. Some Central Valley power plants that rely on surface water for cooling faced water shortages. The industry is being encouraged to switch to more reliable recycled water supplies, which is already the cooling source for a third of the state’s power production. California also produced about half as much hydropower during the latest drought compared to normal years; fossil fuels made up most of the drop. The growing problem of California’s “snow droughts” reduces the state’s ability to store water and produce hydropower in summer, when demand is highest. A warming climate will worsen this problem.
- Which new water supply would be the least costly to develop? D: While it’s a bit hard to generalize—the answer depends on the local cost of water, geography, and project particulars—the cheapest is likely a conservation program to replace old toilets, showerheads, washing machines and the like, according to a 2016 study by the California Public Utilities Commission. Some efficiency measures can even generate more benefits than costs over their lifetime, according to a recent report by the Pacific Institute. For urban areas located near an aquifer, groundwater recharge is second in terms of cost. For areas with poor access to groundwater basins, the best bet for a new water source may be recycling wastewater and piping it directly into the existing water system (called “direct potable reuse”); the state is currently developing policies that would make this possible. Seawater desalination is likely to remain the most expensive new source for most California communities.
- How many of California’s native fish are now at risk of extinction? B: At least 18 of California’s native 122 fish species are now at near-term risk of extinction. The drought’s low flows and high water temperatures add to the effects of dams, water diversions, habitat degradation, and the introduction of non-native species. A total of 90 native fishes are in trouble in one way or the other, with 31 already listed under the Endangered Species Act. The way we manage water leaves our freshwater ecosystems in perpetual drought.