Level 7 - Posttest
Most of the water we use comes from surface-water sources, such
as rivers and lakes. Groundwater is below Earth's surface and must
be pumped to the surface to use. The Central Valley in California
uses both surface water and groundwater for its water supply.
About 20% of the nation's total groundwater pumping is from the
Central Valley.
Based on the graph and this information, which conclusions are
reasonable? Select all that apply.
Ground Water Depletion and Surface Water Withdrawals in the Central Valley
A) Groundwater is being withdrawn faster than
it is replenished.
If the trend continued beyond 2014, the
B) groundwater storage levels are likely below
zero today.
During dry periods, less surface water is
C) available, so more groundwater must be
pumped.
In 1962, the first year shown on the graph,
D) ground water storage was at -20 and
surface water deliveries were 0.
The most significant reduction in
E) groundwater storage occurs during periods
of decreased surface-water deliveries.
Source: USGS https://www2.water.ca.gov/water-data/drought-water-delivery-data
