The Commonwealth of Virginia is a water rich state, but
water is not unlimited. After the statewide drought of 1999-2002 Virginia has been
required to look at water use to sustainably use our available water resources
most effectively. This reporting is still developing but allows us to see and begin
to understand our water use, identify trends and to try to keep the
Commonwealth on a sustainable water path.
The Water Supply Planning (WSP) program was created after
the 1999-2002 drought and requires all localities in Virginia to submit a water
supply plan, either individually, or as part of a regional planning unit that
was amended in 2020 and now requires that a locality report as part of 26
regional planning units. Information reported is what are the water sources and
how much water they currently use. This planning includes both surface water
and groundwater. However, the categories of water use are limited.
DEQ compiles the information included in each Plan, as well
as the water reported water withdrawals collected through the Annual Withdrawal
Reporting from Water Withdrawal Permitting Programs to create a model used to
evaluate the sustainability of our water resources. The results of this
collective analysis are published in the State Water Resources Plan. The most
recent completed plan was published in late 2022 using the data from the
previous year and much of the comments below are paraphrased from the report.
In calendar year 2021 total reported water withdrawals were
approximately 5.66 billion gallons per day (BGD), including the cooling water
withdrawals at nuclear and fossil fuel power generation facilities, which were
77% of water used. Excluding power generation, 2021 reported withdrawals
totaled 1.27 BGD, a 2.9% increase compared to the five-year average and an 8%
increase over 2020- a year impacted by the pandemic. I had not realized how much public water use was impacted by the first year of the pandemic and look forward to seeing the data in the next few years. The 2021 total is the
highest within the last five years and the curve (excluding 2020) seems steeper.
This increase in water withdrawals over the last five years
is largely driven by increased volume from public water supply facilities. Deliveries
of water from public supply to specific users are not reported to DEQ;
therefore, the reported withdrawals for public water supply do not
differentiate between the categories of end users. There is no way to see what
accounts for that growth (or for that matter the sharp fall in 2020), though it seems unlikely that in a period of
decreasing personal water use that increase is just a reflection of population
growth since Virginia’s population grew less than ½% over the five year period.
In 2021 public water supply withdrawals increased by 3.8% (from the 5 year average) to 803 million
gallons per day (MGD). Despite reductions in per capita water use, reported
public water supply withdrawals have steadily increased.
Other drivers of increased reported withdrawals in 2021 were
increases in agricultural irrigation and manufacturing, which were 17.6% (3.4
MGD by volume) and 1.1% (3.9 MGD by volume) higher than the five year average
respectively. Both 2020 and 2021 featured periods of the growing season of
drier than normal conditions which may be contributing to the increase in
irrigation compared to the average.
The DEQ identifies new, continuing, and future priorities, challenges, or other
topics important to water resources management and notes that in 2021,
Commissioners of the Interstate Commission on the Potomac River Basin (ICPRB)
passed a Resolution on Enhancing Water Supply Resilience for the Washington
Metropolitan Area and the major water companies in Northern Virginia. This is
the first step in updating the Low Flow Allocation Agreement (LFAA) of 1978 and
the Water Supply Coordination Agreement (WSCA) of 1982 both are the
foundational agreements of the ICPRB. DEQ presented data indicating that water
supply withdrawals may reduce mean monthly flow of the Potomac River and
tributaries by as much as 40% during moderate and extreme drought flows. This is
significant since research literature indicates that species impacts can
be seen with a 20% reduction in river flow. Drought response may have to change
to protect the native species.
To forecast the potential for climate change to impact
streamflow, DEQ developed a series of climate change scenarios that simulate
how streamflow during a drought may change using the best available global
climate models. These scenarios represent the initial effort by DEQ to address
climate uncertainty and surface water resources within the Commonwealth. While
the models suggest an overall increase in precipitation, they also identified
the potential for more severe periods of drought.
The ability to provide a predictable and reliable water
supply under any climatic condition is critical to Virginia’s economic
well-being. Therefore, developing a process for incorporating the evaluation of
climate change into water withdrawal permitting and water supply planning and
review, is an important element of resiliency planning.
Annual water withdrawal reporting is one of the most
important data sources for DEQ. Reporting of water withdrawals allows for
informed modeling and planning decisions related to the Commonwealth’s future
water demands and availability. However, addressing impacts from water users
that are exempt from the requirement to obtain a VWP surface water
or groundwater withdrawal permit, or otherwise are unpermitted, is a challenge
in managing both surface water and groundwater to provide certainty that this
water will be available for future growth over the long term under all
conditions. Only 21% of surface water withdrawals are subject to permitting
requirements. A process to incorporate the users who are exempt from permits
into the reporting needs to be developed to assure the sustainability of our
water resources.
The proportion of groundwater use that is exempt from
permitting, or otherwise unpermitted, although smaller in absolute terms than
exempt surface water demands, is more difficult to estimate since much of it
comes from domestic or private wells with no requirement to report withdrawals or parts of the state that are not part of a groundwater management area.
In a groundwater management area there are few exemptions from the requirement
to obtain a permit for groundwater withdrawals, but in the rest of the Commonwealth,
the monitoring of groundwater use is limited. Information is essential to
planning for a sustainable Virginia.
Water withdrawals that are reported to DEQ are then linked into the surface water
model, which enables DEQ to prepare up-to-date and accurate water budgets and
conduct cumulative impact analyses in f permit decisions and water
supply planning efforts. Withdrawal data is also used by other programs within
DEQ, other agencies, counties and the public. The effectiveness of the
Commonwealth’s water resource management depends on the comprehensiveness and
accuracy of this self-reported withdrawal information.
In Virginia the Water Withdrawal Reporting Regulation
requires the annual reporting of monthly water withdrawals (surface water and
groundwater) of volumes greater than an average of 10,000 gallons per day (GPD)
during any month, or one million gallons per month for crop irrigation. The
regulation allows the submission of metered and estimated water withdrawal
information. DEQ maintains withdrawal data as far back as 1982, but there has
been limited work to determine what is the supply of water available to the Commonwealth.
We are coming to the point where we need to know that.