Elephant Butte technical update and history

Flow at San Marcial Floodway as of 11:00 a.m., Tuesday, 15 May 2007:
1,950 cubic feet per second (1,860 to 2,020 c.f.s. in past 71 hours.

Flow out of Elephant Butte dam: 1,010 c.f.s. (994 to 1,050 c.f.s. in past 71 hours).

Lake as of 9:00 a.m., Tuesday, 15 May 2007:
4,344.32 feet above benchmark elevation, 562,590 acre feet.
Up .12' (1.4 inches) and 1,655 acre feet in 24 hours.
Up .36' (4.3 inches) and 4,970 acre feet in 71 hours.

Recent History (elev. 4,407 with approx. 1,950,000 acre feet is capacity)

4,344.32 562,590 May 15, 2007, 0900
4,343.26 548,050 May 5, 2007 -- lowest point during spring irrigation
4,343.84 555,970 April 30, 2007
4,347.62 609,050 March 31, 2007
4,347.76 611,060 March 26, 2007 -- initial spring high
4,346.88 598,460 February 28, 2007
4,346.00 585,997 February 20, 2007, 0400
4,344.02 558,400 January 31, 2007
4,343.98 557,894 January 31, 2007, 1200
4,340.82 515,350 January 1, 2007

2006:
4,343.98 . . . . . . . 557,894 . . . . . . . Jan. 31, '07 (1200)
4,340.54 . . . . . . . 511,683 . . . . . . . Dec. 30 (0800)
4,336.52 . . . . . . . 460,330 . . . . . . . Nov. 30
4,331.24 . . . . . . . 397,510 . . . . . . . Oct. 31
4,327.10 . . . . . . . 351,800 . . . . . . . Sept. 30
4,325.18 . . . . . . . 331,550 . . . . . . . Aug. 31
4,308.50 . . . . . . . 183,870 . . . . . . . July 28 low point
4,339.88 . . . . . . . 503,030 . . . . . . . March 5 high point
4,334.06 . . . . . . . 430,410 . . . . . . . January 1, 2006

2005 :
4,327.36 354,607 November 7, 2005
4,325.28 332,602 October 11, 2005, 7-9 a.m., fall seasonal low point
4,325.58 335,739 October 7, 2005
~4,327 ~350,950 September 27, 2005
~4,310 January 1, 2005

2004
~4,297 low point for year (autumn)
~4,313 January 1, 2004

2003
~4,304 low point for year (autumn)
~4,326 January 1, 2003

2002
~4,321 low point for year (autumn)
~4,364 January 1, 2002

2001
~4,362 low point for year (autumn)
~4,381 January 1, 2001

2000
~4,379 low point for year (autumn)
~4,396 January 1, 2000

1999
~4,394 low point for year (spring)
~4,396 January 1, 1999

1998
~4,394 low point for year (autumn)
~4,405 high point for year (spring)
~4,402 January 1, 1998

1997
~4,398 low point for year (autumn)
~4,400 high point for year (spring)
~4,398 January 1, 1997


1996
~4,396 low point for year (autumn)
~4,407 high point for year (early spring) Spillway!
~4,406 January 1, 1996

1995
~4,404 low point for year (autumn)
~4,406 high point for year (spring)
~4,406 January 1, 1995

Comparison to operating plan:

According to the Operating Plan, the lake should have been receiving about 377 c.f.s., releasing 1,350 c.f.s., and at elevation 4,341.74 with 527,618 acre feet, losing about 2,000 a.f. and 1.7 inches per day.

The actual numbers are 1,950 c.f.s. inflow, 1,010 c.f.s. outflow, with elevation 2.58 feet higher than projected and 34,972 acre feet more than projected for this date, with the lake gaining in water (1,655 a.f.) and surface elevation (1.2 inches).

Although the rate of discharge may soon increase to 1,830 c.f.s., the inflow is likely to keep up and allow the lake level to rise moderately during the next few weeks. The operating plan projection for June 30th of 375,308 acre feet and elevation 4,329.26 feet is likely too pessimistic; this is a level that may not be seen until late July.

The operations plan shows only about 100,000 a.f. of inflow through June of 2007 and thus is more conservative than the NRCS May water supply forecast of 255,000 acre feet of Rio Grande water at San Marcial through July of 2007 (45% of the 573,000 a.f. average).