By Brian Wheeler
Tuesday, August 30, 2011
water demand forecast
for Charlottesville-Albemarle has been updated in advance of a public hearing to be held in September.
AECOM Technology Corp.’s projections now show slightly less water consumption, but greater projected population growth.
Download AECOM’s August 2011 water demand forecast
Late last week, the
Rivanna Water and Sewer Authority
released AECOM’s final forecast updating
a July draft
. The state is requiring localities to submit a comprehensive water supply plan by Nov. 2.
“The final regional water supply demands reflect the future human water demands of the regional water supply planning area which includes the citizens in the City of Charlottesville, Albemarle County, Town of Scottsville, and Crozet,” said Kim Shorter, a water supply specialist with AECOM, in an email. “These forecasts will support development of the Regional Water Supply Plan, required by the Virginia Local and Regional Water Supply Planning regulations.”
This research is separate from the water storage plan being implemented for the urban water supply, which includes a new earthen dam and water supply pipeline to accommodate future droughts and population growth. Yet its findings allow a review of that 50-year water plan’s assumption that the community would need 18.7 million gallons per day (mgd) by 2055.
That original demand assumption was part of the information local leaders had in hand when voting to approve the $140 million water supply plan. Since, both the demand projections and the approved plan have come under intense scrutiny by those who believe dredging of the
South Fork Rivanna Reservoir
could provide enough water for the city, urban areas of Albemarle and the University of Virginia.
A report released in July
by the RWSA indicated one-time dredging would produce a so-called “safe yield” of 9.2 mgd and continuous dredging of South Fork for 50 years would produce a safe yield of 10.3 mgd.
AECOM’s forecast revises the projected water needs downward to 16.17 mgd in 2055, a 13.5 percent drop from the water storage plan’s original assumptions. The report indicates current water usage is about 9.76 mgd.
AECOM’s estimate extends to 2060, when it projects demand will be 16.96 mgd. The revised figures are a slight decrease from AECOM’s July estimate of 17.01 mgd.
AECOM’s forecast method evaluates population projections, jobs, residential per capita water use and per employee water use. Baseline projections are then evaluated against other factors like water conservation, use of efficient water fixtures, area comprehensive plans and potential fluctuations in population or employment.
While AECOM considered scenarios that called for greater water usage, it ultimately lowered its estimates somewhat from the established baseline despite rising population projections.
At a July public input session
, residents raised concerns about AECOM’s population projections for Charlottesville. In the previous report, the city’s 2010 population of 43,475 was projected to increase to 71,500 in 2060, reportedly based upon input from city planners.
At the last City Council meeting, Mayor
asked city staff for feedback on the population projection, which he called a “pretty shocking estimate.”
“AECOM had expressed to folks that we had provided those numbers to them, which in fact we did not,” said City Manager
to council on Aug 1. “[AECOM] said they would go back … and reevaluate those numbers.”
In its final report, AECOM revised its estimate and disaggregated the University of Virginia student population between Charlottesville and Albemarle. The result is a revised city population projection of 63,482.
However, with the addition of on-grounds students that live in Albemarle but use city water, the population for the city’s “water service area” is projected to be 72,642, representing a further increase of 1,142 from the July estimate.
“We received additional information to help us refine the population forecasts,” Shorter said. “One of the refinements included a closer look at UVa population and the difference between the water-supplied population and the demographic population.”
Rebecca Quinn, chair of
Citizens for a Sustainable Water Plan
, which favors dredging before building a new dam, said she remains concerned about the city population estimates and was surprised to see them go up even higher in the latest report.
“How can it go up?” asked Quinn. “I would like to know what the city has to say about the population numbers. It looks like they have simply taken the growth rate from the last six years and straight-lined it.”
, the city’s director of Neighborhood Development Services, said he thought the new population numbers were “reasonable.”
“What they basically did was lower that number from 71,500 to 63,482,” said Tolbert. “As they explained to me, the water service area includes the city plus the [UVa] students living on Grounds who do not live in the city.”
AECOM also raised its long-term estimate for Albemarle’s population of urban water users.
According to the report, the Albemarle County Service Authority had 51,095 urban water users in 2010. That is projected to increase to 112,210 in 2060 as the county directs further population growth into its urban growth areas on public water. That represents an increase of 10,348 from the July estimate.
“I think the way it was developed was about as reasonable a way as you could develop one,” Tolbert added. “It is very difficult to do a population projection in this community.”
On Sept. 13 AECOM will present its final forecast to a joint meeting of the “four boards” — the RWSA board, the ACSA board, Charlottesville City Council, and the Albemarle Board of Supervisors. A separate presentation will be made to Scottsville’s Town Council on Sept. 12.