Drought Report Covering Corps of Engineer Reservoir Projects in the Wilmington District

DEPARTMENT OF THE ARMY
WILMINGTON DISTRICT. CORPS OF ENGINEERS
P. O. BOX 1890
WILMINGTON. NORTH CAROLINA 28402

IN REPLY REFER TO
Reservoir Regulation Section

August 8, 1986

Mr. John Morris, Director
Division of Water Resources
North Carolina Department of Natural
Resources and Community Development
Box 27687
Raleigh, North Carolina 27611

Dear Mr. Morris:

Enclosed for your information is a drought report covering
Corps of Engineer reservoir projects in the Wilmington
District.

Sincerely,

Jaman Vithalani, P.E.
Chief, Engineering Division

Enclosure

SAWEN-HA 6 August 1986

DROUGHT STATUS REPORT FOR RESERVOIRS
IN THE WILMINGTON DISTRICT

NARRATIVE

1. Preface. This is the second report summarizing current drought conditions
in the Wilmington District for 1986

2. General. In North Carolina and Virginia, uncontrolled streamflows are at
low levels. Although some rainfall amounts have occurred across North Carolina
and Virginia, most of both states are in an extreme drought making it the driest
period in almost 100 years. A map showing drought severity is enclosed as
exhibit 6. Exhibit 6 also illustrates, nationally, the rainfall needed to end
the drought.

3. Drought. Table 1 below illustrates the values used in the Palmer Index to
describe recent weather conditions.

Table 1 - Palmer Index

Palmer Index Character of Recent Weather

.49 TO -0.49 . . . . . . . . . . . . . . . . . Near Normal
-.50 TO -0.99 . . . . . . . . . . . . . . . . Incipient Drought
- 1.00 TO -1.99 . . . . . . . . . . . . . . . Mild Drought
- 2.00 TO -2.99 . . . . . . . . . . . . . . . . Moderate Drought
- 3.00 TO -3.99 . . . . . . . . . . . . . . . . Severe Drought
-4.00 OR LESS . . . . . . . . . . . . . . . .Extreme Drought

Palmer Index values were updated on 27 July by the National Weather Service
office in Raleigh, NC, for the geographic areas of North Carolina. These values
are shown below in table 2 and are also indicative of adjacent areas of
Virginia.

Table 2 - Geographic Drought Conditions for North Carolina

Palmer Change From Rain Needed Drought
Region Index Two Weeks Ago To End Drought Description

Southern Mountains -6.25 -0.50 19.34 Extreme
Northern Mountains -6.45 -0.80 19.42 Extreme
Northern Piedmont -5.64 0.70 15.38 Extreme
Central Piedmont -6.04 -0.36 17.67 Extreme
Southern Piedmont -6.45 -0.56 18.76 Extreme
So. Coastal Plain -3.05 -0.18 10.80 Severe
Central Coastal Plain -3.51 0.54 12.60 Severe
Northern Coastal Plain -3.78 -0.25 12.44 Severe

Table 3 illustrates how recent inflow and rainfall data compare with historical
averages at Corps projects within the Wilmington District.

TABLE 3
INFLOW-RAINFALL CONDITIONS
WILMINGTON DISTRICT
DECEMBER 1985-JULY1986
JOHN H.KERR PROJECT

MONTHLY CUMULATIVE MONTHLY RAINFALL CUMULATIVE RAINFALL
INFLOW (CFS) OBS/AVG INFLOW (CFS) OBS/AVG INCHES OBS/AVG INCHES OBS/AVG
MONTHOBS AVG% OBS AVG% MONTH OBS AVG% OBS AVG%
DEC 85 72477389 98. 1 7247 7389 98. 1 DEC 1. 53. 2246. 6 1. 53. 2246. 6
JAN 86 4085 10310 39. 6 11332 17699 64. 0 JAN 86 1. 163. 3634. 5 2. 666. 58 40. 4
FEB 6757 11810 57. 2 18089 29509 61. 3 FEB2. 523. 2976. 6 5. 18 9. 87 52. 5
MARCH 7579 12829 59. 1 25668 42338 60. 6 MARCH 1. 743. 7945. 9 6. 92 13. 6650. 7
APRIL 3414 10747 31. 8 29082 53085 54. 8 APRIL 0. 893. 3826. 3 7. 81 17. 04 45. 8
MAY 3231 7596 42. 5 32313 60681 53. 3 MAY3. 083. 8979. 2 10. 89 20. 93 52. 0
JUNE 11935910 20. 2 33506 66591 50. 3 JUNE 0. 563. 8614. 5 11. 45 24. 79 46. 2
JULY 14495388 26. 9 34955 71979 48. 6 JULY 2. 794. 4462. 8 14. 24 29. 2348. 7

PHILPOTT PROJECT
MONTHLY CUMULATIVE MONTHLY RAINFALL CUMULATIVE RAINFALL
INFLOW(CFS) OBS/AVG INFLOW(CFS)OBS/AVG INCHES OBS/AVG INCHES OBS/AVG
MONTH OBS AVG% OBS AVG% MONTH OBS AVG% OBS AVG%
DEC 85 284 267 106. 4 284 267 106. 4 DEC1. 263. 6334. 7 1. 26 3. 63 34. 7
JAN 86 212 311 68. 2 496 578 85. 8 JAN 86 1. 003. 7226. 9 2. 267. 35 30. 7
FEB 254 350 72. 6 750 928 80. 8 FEB2. 71 3. 5476. 6 4. 97 10. 89 45. 6
MARCH 251 394 63. 7 1001 1322 75. 7 MARCH 2. 064. 61 44. 7 7. 03 15. 50 45. 4
APRIL 152 398 38. 2 1153 1720 67. 0 APRIL 0. 754. 1318. 2 7. 78 19. 63 39. 6
MAY 150 303 49. 5 1303 2023 64. 4 MAY3. 61 4. 6477. 8 11. 39 24. 27 46. 9
JUNE 77 258 29. 8 1380 2281 60. 5 JUNE 0. 624. 7813. 0 12. 01 29. 05 41. 3
JULY 70 226 31. 0 1450 2507 57. 8 JULY 4. 765. 1093. 3 16. 77 34. 15 49. 1

B. E.JORDAN PROJECT
MONTHLY CUMULATIVE MONTHLY RAINFALL CUMULATIVE RAINFALL
INFLOW (CFS) OBS/AVG INFLOW(CFS)OBS/AVG INCHES OBS/AVG INCHES OBS/AVG
MONTH OBS AVG% OBS AVG% MONTH OBS AVG% OBS AVG%
DEC 85 1665 1608 103. 5 1665 1608 103. 5 DEC1. 473. 4342. 9 1. 473. 4342. 9
JAN 86 6582575 25. 62323 4183 55. 5 JAN 86 1. 003. 6727. 2 2. 477. 10 34. 8
FEB 1021 3064 33. 33344 7247 46. 1 FEB1. 903. 5453. 7 4. 37 10. 64 41. 1
MARCH 18982896 65. 5 5242 10143 51. 7 MARCH 2. 413. 9261. 5 6. 78 14. 56 46. 6
APRIL 3882221 17. 5 5630 12364 45. 5 APRIL 0. 983. 4228. 7 7. 76 17. 98 43. 2
MAY 286 1333 21. 5 5916 13697 43. 2 MAY2. 053. 77 54. 4 9. 81 21. 75 45. 1
JUNE 5811325. 1 5974 14829 40. 3 JUNE 1. 554. 0538. 3 11. 36 25. 80 44. 0
JULY 140 996 14. 1 6114 15825 38. 6 JULY 3. 164. 9963. 3 14. 52 30. 79 47. 2

FALLS LAKE PROJECT
MONTHLY CUMULATIVE MONTHLY RAINFALL CUMULATIVE RAINFALL
INFLOW (CFS) OBS/AVG INFLOW(CFS)OBS/AVG INCHES OBS/AVG INCHES OBS/AVG
MONTH OBS AVG% OBS AVG% MONTH OBS AVG% OBS AVG%
DEC 85 747 736 101. 5 747 736 101. 5 DEC1. 39 3. 342. 1 1. 39 3. 3 42. 1
JAN 86 339 1241 27. 3 1086 1977 54. 9 JAN 86 1. 323. 5836. 9 2. 716. 88 39. 4
1 FEB 453 1535 29. 5 1539 3512 43. 8 FEB1. 873. 44 54. 4 4. 58 10. 32 44. 4
MARCH 1120 1498 74. 8 2659 5010 53. 1 MARCH 2. 983. 93 75. 8 7. 56 14. 25 53. 1
APRIL 134 1199 11. 2 2793 6209 45. 0 APRIL 1. 103. 3832. 5 8. 66 17. 63 49. 1
MAY 149 669 22. 3 2942 6878 42. 8 MAY2. 733. 84 71. 1 11. 39 21. 47 53. 1
JUNE-52 484-10. 7 2890 7362 39. 3 JUNE 0. 844. 0320. 8 12. 23 25. 50 48. 0
JULY 24 5234. 6 2914 7885 37. 0 JULY 4. 304. 9287. 4 16. 53 30. 42 54. 3

2

TABLE 3 (CONT.)
INFLOW - RAINFALL CONDITIONS
WILMINGTON DISTRICT
DECEMBER 1985-JULY 1986

W.KERR SCOTT PROJECT
MONTHLY CUMULATIVE MONTHLY RAINFALL CUMULATIVE RAINFALL
INFLOW (CFS) OBS/AVG INFLOW (CFS)OBS/AVG INCHES OBS/AVG INCHES OBS/AVG
MONTHOBS AVG% OBS AVG% MONTH OBS AVG% OBS AVG%
DEC 85 473 539 87. 8 473 539 87. 8 DEC1. 343. 8434. 9 1. 343. 8434. 9
JAN 86 357 585 61. 0 830 1124 73. 8 JAN 86 1. 433. 7138. 5 2. 777. 5536. 7
FEB 457 726 62. 9 1287 1850 69. 6 FEB 2. 324. 0657. 1 5. 09 11. 6143. 8
MARCH 571 815 70. 1 18582665 69. 7 MARCH 3. 455. 2865. 3 8. 54 16. 8950. 6
APRIL343 809 42. 4 2201 3474 63. 4 APRIL 0. 554. 2812. 9 9. 09 21. 1742. 9 "
MAY 388 664 58. 4 25894138 62. 6 MAY5. 224. 86 107. 4 14. 31 26. 0355. 0
JUNE 251 592 42. 4 28404730 60. 0 JUNE 0. 424. 908. 57 14. 73 30. 9347. 6
JULY 182 477 38. 2 30225207 58. 0 JULY 2. 81 5. 12 54. 88 17. 54 36. 0548. 7

3

4. Condition of Reservoirs and Recommendations.

a. J. H. Kerr Dam and Reservoir. Since 1 December of last year, the
average basin rainfall above Kerr Dam has averaged 51% below normal. Inflow to
the project since December has also averaged about 51% below normal. The
lake elevation is 295.60 feet mean sea level or 3.9 feet below rule curve. The
area above Kerr is in an extreme drought. About 0.44 inch of runoff is needed
in the drainage area above Kerr Dam where 65.1% of the power pool has been
utilized. Wilmington District has made an informal contact with Southeastern
Power Administration to request Virginia Power Company and Carolina Power and
Light Company to reduce generation at Kerr to a minimum without violating
minimum downstream water quality flow needs. The remainder of the declared
energy would go into the energy storage account. A projection of Kerr Reservoir
levels is shown on exhibit 1 as well as rainfall, daily inflow, and recorded
reservoir levels. Starting on 28 July, 225 MWH of electricity (weekly) was
being interchanged from Kerr to Philpott Lake in order to balance out the
remaining storage between these two projects. This measure as well as
requesting the power companies to put some declared energy in storage should
help Kerr maintain a reservoir level above elevation 293 feet, m.s.l. until 15
September. If curtailment of generation is not successful and drought inflows
continue, Kerr & Philpott are forecast to fail to meet contractual dependable
generating capacity by 5 September.

b. Philpott Lake. Rainfall above Philpott and inflow to Philpott Lake
since December 1985 have averaged 51% and 42% below normal, respectively.
Drought conditions at Philpott are extreme with the lake elevation about
6.4 feet below rule curve. About 1.6 inches of runoff is needed in the drainage
area to refill Philpott Lake where 33.0% of the power pool has been utilized.
As stated previously in paragraph 4a, Philpott project on 28 July began
generating 225 MWH per week extra electricity for transferral to Kerr Dam. A
plot of daily rainfall and inflow recorded lake levels to date, and a projection
of reservoir performance is included as exhibit 2. The lake is forecasted to be
at elevation 951 by mid-October, if a continuation of drought inflows persists.

c. B. Everett Jordan Dam and Lake. Rainfall above Jordan Dam and inflow to
Jordan Lake since December 1985 have averaged 53% and 61% below normal,
respectively. Jordan Lake is 5.6 feet below normal pool. Approximately
0.76 inch of runoff is needed in order to refill Jordan Lake where 48.9% of the
conservation pool has been utilized. If conditions do not improve in the Jordan
drainage area, a request will be made to the State of North Carolina to reduce
downstream water quality target flow requirements. To maintain the integrity of
the Jordan project, target flows must be reduced from 600 cubic feet per second
(c.f.s ) to 500 c.f.s. when the lake elevation reaches 208 feet, m.s.l. Further
reductions to 400 and 300 c.f.s. will be made if the lake drops to elevation 205
and 203.0 feet, m.s.l., respectively. This scheme should extend storage in
Jordan through the end of the year if drought inflows continue. Otherwise, the
remaining conservation storage capacity will be depleted by mid-October.
Exhibit 3 shows daily rainfall and inflow, recorded lake levels to date, and
projected lake levels.

4

d. Falls Lake. Rainfall above Falls Dam and inflow to Falls Lake since
December 1985 have averaged 46% and 63% below normal, respectively. Falls Lake
is currently 5.1 feet below the summer rule curve elevation of 251.0 feet,
m.s.l. (See exhibit 4). A runoff of 1.25 inches is needed to refill Falls Lake
to the summer rule curve. At this time, 22.4% of the conservation pool storage
for water supply, 57.2% of the conservation pool storage for water quality and
low flow, and 43.7% of the total conservation pool has been utilized at Falls
Lake. If current conditions continue, water quality and low flow storage will
be depleted before the lake elevation reaches 240 feet m.s.l. Beaverdam
impoundment may have to be emptied to the level of Falls Lake prior to the
present schedule which allows Falls to reach elevation 240 feet m.s.l. before
opening the gates at Beaverdam. At the present rate of inflow, Falls Lake is
expected to reach elevation 240 feet m.s.l. by early October.

e. W. Kerr Scott Dam and Reservoir.. Rainfall above Scott Reservoir for
the past 7 months has averaged 51% below normal and inflow has been about
42% below normal. The area above W. Kerr Scott Dam is in an extreme drought.
The lake elevation is about 6.2 feet below normal (See exhibit 5). A runoff of
0.43 inches is needed to refill the lake where 24.3% of the conservation pool
has been utilized.

At this time, W. Kerr Scott is in the best shape of all of the reservoir
projects in the Wilmington District due primarily to a scheme of discharges
instigated in 1982, whereby outflows are reduced according to a scheduled
step-down which corresponds with a lowering of the lake level. This operation
has enhanced the viability of the water supply systems of Winston-Salem and
Wilkes County, North Carolina.

5

AVERAGE BASIN RAINFALL
H. KERR 1986

Average Basin Rainfall
J. H. Kerr 1986

Inflow 1986

EXHIBIT 1

PHILPOTT 1986
AVERAGE BASIN RAINFALL

INFLOW

EXHIBIT 2

B. E. JORDAN 1986

AVERAGE BASIN RAINFALL

INFLOW

EXHIBIT 3

FALLS 1986

AVERAGE BASIN RAINFALL

INFLOW 1986

EXHIBIT 4

W. K. SCOTT 1986
AVERAGE BASIN RAINFALL

INFLOW 1986

EXHIBIT 5

DROUGHT SEVERITY
(LONG TERM, PALMER)
JULY 19, 1986
EXHIBIT 6