.
Lake Merced Water Level vs.
Monthly
Rainfall
Monthly record from May 1996
As is apparent from the figure below, there has been a significant downward trend in the level of Lake Merced. At its lowest, in September 2002, this level approached the record low set during the drought years of the mid-nineties.
That downward trend was stopped through the addition of "system water" to Lake Merced. A total of approximately five feet of water has been added since October 2002. The problems haven't all been solved, but we are finally making some progress.
Lake
Level and Rainfall -- Monthly Readings
Data provided by the Lake Merced Pumping Station
Beginning in October '94 the report
recorded
at the Lake Merced Pumping Station was approximately 1.3 feet lower
than the
historical relationship to City Datum. That is, a LMPS report of
20.30
feet translates into 21.60 feet to comply with the historical
relationship
between that reading and City Datum. We have corrected this data
to
reflect that difference.
|
Month |
Lake Level (ft@eom) |
City
Datum |
Rainfall
|
Change in Level |
|
|
May '96 |
20.15 |
2.65 |
1.49 |
(feet) |
(inches) |
|
Jun '96 |
19.50 |
2.00 |
0 |
-0.65 |
-7.80 |
|
Jul '96 |
18.98 |
1.48 |
0 |
-0.52 |
-6.24 |
|
Aug '96 |
18.56 |
1.06 |
0.02 |
-0.42 |
-5.04 |
|
Sept '96 |
18.16 |
0.66 |
0.01 |
-0.40 |
-4.80 |
|
Oct '96 |
17.91 |
0.41 |
0.19 |
-0.25 |
-3.00 |
|
Nov '96 |
18.08 |
0.58 |
3.50 |
0.17 |
2.04 |
|
Dec '96 |
18.69 |
1.19 |
6.87 |
0.61 |
7.32 |
|
Jan '97 |
19.58 |
2.08 |
6.71 |
0.89 |
10.68 |
|
Feb '97 |
19.49 |
1.99 |
0.27 |
-0.09 |
-1.08 |
|
Mar '97 |
19.48 |
1.98 |
0.30 |
-0.01 |
-0.12 |
|
Apr '97 |
19.55 |
2.05 |
0.32 |
0.07 |
0.84 |
|
May '97 |
19.11 |
1.61 |
0.15 |
-0.44 |
-5.28 |
|
Jun '97 |
18.68 |
1.18 |
0.32 |
-0.43 |
-5.16 |
|
Jul '97 |
18.14 |
0.64 |
0 |
-0.54 |
-6.48 |
|
Aug '97 |
17.76 |
0.26 |
0.26 |
-0.38 |
-4.56 |
|
Sept '97 |
17.32 |
-0.18 |
0.11 |
-0.44 |
-5.28 |
|
Oct '97 |
17.05 |
-0.45 |
0.47 |
-0.27 |
-3.24 |
|
Nov '97 |
17.33 |
-0.17 |
2.07 |
0.28 |
3.36 |
|
Dec '97 |
17.59 |
0.09 |
0.87 |
0.26 |
3.12 |
|
Jan '98 |
19.04 |
1.54 |
9.90 |
1.45 |
17.40 |
|
Feb '98 |
20.64 |
3.14 |
12.57 |
1.60 |
19.20 |
|
Mar '98 |
20.73 |
3.23 |
2.22 |
0.09 |
1.08 |
|
Apr '98 |
20.59 |
3.09 |
1.78 |
-0.17 |
-2.04 |
|
May '98 |
20.67 |
3.17 |
3.07 |
0.08 |
0.96 |
|
Jun '98 |
20.29 |
2.79 |
0.05 |
-0.38 |
-4.56 |
|
Jul '98 |
20.03 |
2.53 |
0 |
-0.21 |
-2.52 |
|
Aug '98 |
19.74 |
2.24 |
0 |
-0.29 |
-3.48 |
|
Sep '98 |
19.51 |
2.01 |
0 |
-0.23 |
-2.76 |
|
Oct '98 |
19.28 |
1.78 |
0.73 |
-0.23 |
-2.76 |
|
Nov ‘98 |
19.55 |
2.05 |
3.83 |
0.27 |
3.24 |
|
Dec ‘98 |
19.76 |
2.26 |
0.37 |
0.21 |
2.52 |
|
Jan ‘99 |
20.12 |
2.62 |
3.97 |
0.36 |
4.32 |
|
Feb '99 |
20.65 |
3.15 |
6.88 |
0.53 |
6.36 |
|
Mar '99 |
20.71 |
3.21 |
2.52 |
0.06 |
0.72 |
|
Apr '99 |
20.65 |
3.15 |
2.99 |
-0.06 |
-0.72 |
|
May '99 |
21.14 |
3.64 |
0.11 |
0.49 |
5.88 |
|
Jun '99 |
20.55 |
3.04 |
0.02 |
-0.59 |
-7.08 |
|
Jul '99 |
20.10 |
2.60 |
0 |
-0.45 |
-5.40 |
|
Aug '99 |
19.85 |
2.35 |
0.13 |
-0.25 |
-3.00 |
|
Sep '99 |
19.59 |
2.09 |
0 |
-0.26 |
-3.12 |
|
Oct '99 |
19.44 |
1.94 |
0.47 |
-0.15 |
-1.80 |
|
Nov '99 |
19.53 |
2.03 |
2.21 |
0.09 |
1.08 |
|
Dec '99 |
19.49 |
1.99 |
0.56 |
-0.04 |
-0.48 |
|
Jan '00 |
19.99 |
2.49 |
7.37 |
0.50 |
6.00 |
|
Feb '00 |
20.70 |
3.20 |
7.34 |
0.71 |
8.52 |
|
Mar '00 |
20.74 |
3.24 |
1.76 |
0.04 |
0.48 |
|
Apr '00 |
20.81 |
3.31 |
1.20 |
0.07 |
0.84 |
|
May '00 |
20.53 |
3.03 |
1.25 |
-0.28 |
-3.36 |
|
Jun '00 |
20.12 |
2.62 |
0.20 |
-0.41 |
-4.92 |
|
Jul '00 |
19.83 |
2.33 |
0.00 |
-0.29 |
-3.48 |
|
Aug '00 |
19.53 |
2.03 |
0.01 |
-0.30 |
-3.60 |
|
Sep '00 |
19.29 |
1.79 |
0.26 |
-0.24 |
-2.88 |
|
Oct '00 |
19.32 |
1.82 |
1.27 |
0.03 |
0.36 |
|
Nov '00 |
19.26 |
1.76 |
0.25 |
-0.06 |
-0.72 |
|
Dec '00 |
19.24 |
1.74 |
0.57 |
-0.02 |
-0.24 |
|
Jan '01 |
19.55 |
2.05 |
2.98 |
0.31 |
3.72 |
|
Feb '01 |
20.68 |
3.18 |
6.48 |
1.13 |
13.60 |
|
Mar '01 |
19.99 |
2.49 |
4.28 |
-0.69 |
-8.28 |
|
Apr '01 |
19.80 |
2.80 |
1.82 |
-0.19 |
-2.28 |
|
May '01 |
19.41 |
1.91 |
0.00 |
-0.39 |
-4.68 |
|
Jun '01 |
18.93 |
1.43 |
0.21 |
-0.48 |
-5.76 |
|
Jul '01 |
18.52 |
1.02 |
0.00 |
-0.41 |
-4.92 |
|
Aug '01 |
18.16 |
0.66 |
0.00 |
-0.36 |
-4.32 |
|
Sep '01 |
17.91 |
0.41 |
0.50 |
-0.25 |
-3.00 |
|
Oct '01 |
17.72 |
0.22 |
0.38 |
-0.19 |
-2.28 |
|
Nov '01 |
17.92 |
0.42 |
2.33 |
0.20 |
2.40 |
|
Dec '01 |
18.90 |
1.40 |
8.85 |
0.98 |
11.76 |
|
Jan '02 |
18.99 |
1.49 |
1.45 |
0.09 |
1.08 |
|
Feb '02 |
19.18 |
1.68 |
1.72 |
0.19 |
2.28 |
|
Mar '02 |
19.13 |
1.63 |
2.58 |
-0.05 |
-0.60 |
|
Apr '02 |
18.70 |
1.20 |
0.40 |
-0.43 |
-5.16 |
|
May '02 |
18.53 |
1.03 |
0.86 |
-0.17 |
-2.04 |
|
Jun '02 |
18.14 |
0.64 |
0.00 |
-0.39 |
-4.68 |
|
Jul '02 |
17.78 |
0.28 |
0.00 |
-0.36 |
-4.32 |
|
Aug '02 |
17.47 |
-0.03 |
0.00 |
-0.31 |
-3.72 |
|
Sep '02 |
17.20 |
-0.30 |
0.00 |
-0.27 |
-3.24 |
|
Oct '02* |
18.60 |
1.10 |
0.00 |
1.40 |
16.80 |
|
Nov '02 |
18.64 |
1.14 |
4.15 |
0.04 |
0.48 |
|
Dec '02 |
19.69 |
2.19 |
6.74 |
1.05 |
12.60 |
|
Jan '03 |
19.94 |
2.44 |
2.82 |
0.25 |
3.00 |
|
Feb '03 |
20.00 |
2.50 |
2.16 |
0.06 |
0.72 |
|
Mar '03 |
19.96 |
2.46 |
0.91 |
-0.04 |
-0.48 |
|
Apr '03 |
20.42 |
2.92 |
3.20 |
0.46 |
5.52 |
|
May '03 |
20.18 |
2.68 |
1.11 |
-0.24 |
-2.88 |
|
Jun '03 |
19.73 |
2.23 |
0.00 |
-0.45 |
-5.40 |
|
Jul '03** |
19.75 |
2.25 |
0.00 |
0.02 |
0.24 |
|
Aug '03** |
21.05 |
3.55 |
0.00 |
1.30 |
15.60 |
|
Sep
'03*** |
21.02 |
3.52 |
0.00 |
-0.03 |
-0.36 |
|
Oct
'03*** |
21.00 |
3.50 |
0.00 |
-0.02 |
-0.24 |
|
Nov
'03 |
21.16 |
3.66 |
2.12 |
0.16 |
1.92 |
|
Dec
'03 |
21.89 |
4.39 |
7.08 |
0.73 |
8.76 |
|
Jan
'04 |
22.04 |
4.54 |
3.42 |
0.15 |
1.80 |
|
Feb
'04 |
22.51 |
5.01 |
6.32 |
0.47 |
5.64 |
|
Mar '04 |
22.29 |
4.79 |
0.95 |
-0.22 |
-2.64 |
|
Apr
'04 |
22.01 |
4.51 |
0.15 |
-0.28 |
-3.36 |
|
May
'04 |
21.65 |
4.15 |
0.00 |
-0.36 |
-4.32 |
|
Jun
'04 |
21.29 |
3.79 |
0.00 |
-0.36 |
-4.32 |
|
Jul
'04 |
21.03 |
3.53 |
0.00 |
-0.26 |
-3.12 |
|
Aug
'04 |
20.80 |
3.30 |
0.00 |
-0.23 |
-2.76 |
|
Sept
'04 |
20.53 |
3.03 |
0.00 |
-0.27 |
-3.24 |
| Oct
'04 |
20.65 |
3.15 |
3.07 |
0.12 |
1.44 |
| Nov
'04 |
20.70^ |
3.20 |
1.58 |
0.05 |
0.60 |
| Dec
'04 |
21.88 |
4.38 |
8.76 |
1.18 |
14.16 |
| Jan
'05 |
22.19 |
4.69 |
3.98 |
0.31 |
3.72 |
| Feb
'05 |
22.49 |
4.99 |
5.16 |
0.30 |
3.60 |
| Mar
'05 |
22.72 |
5.22 |
4.50 |
0.23 |
2.76 |
| Apr
'05 |
22.60 |
5.10 |
0.25 |
-0.12 |
-1.44 |
| May
'05 |
22.44 |
4.94 |
1.68 |
-0.16 |
-1.92 |
| Jun
'05 |
22.21 |
4.71 |
1.70 |
-0.23 |
-2.76 |
| Jul
'05 |
22.03 |
4.53 |
0.00 |
-0.18 |
-2.16 |
| Aug
'05 |
21.85 |
4.35 |
0.00 |
-0.18 |
-2.16 |
| Sep
'05 |
21.69 |
4.19 |
0.00 |
-0.16 |
-1.92 |
| Oct
'05 |
21.66 |
4.16 |
0.45 |
-0.03 |
-0.36 |
| Nov
'05 |
21.76 |
4.26 |
2.01 |
0.10 |
1.20 |
| Dec
'05 |
22.78 |
5.28 |
9.15 |
1.02 |
12.24 |
| Jan
'06 |
23.00 |
5.50 |
2.20 |
0.22 |
2.64 |
| Feb
'06 |
23.21 |
5.71 |
1.85 |
0.21 |
2.62 |
| Mar
'06 |
23.91 |
6.41 |
6.11 |
0.70 |
8.40 |
| Apr
'06 |
24.27 |
6.77 |
0.32 |
0.36 |
4.32 |
*Note also that during that month approximately 1.5 ft. of water was
added from
the Hetch-Hetchy system, accounting for the 1.4 ft. rise in lake level.
An additional 0.5 ft. was added in April 2003.
** Water from the Hetch-Hetchy system was added to the lake during July
and
August, 2003. We do not know the amount of water added.
However,
before the water additions began in mid-July the lake reached a low
level of
19.47 feet on July 23.
*** During September and October, 2003 water has been added to maintain
the
lake level at nearly 21 feet. This does not represent a normal or
sustainable lake level response to natural conditions.
^ A new lake level monitor was installed during November 2005, and
became operative as of 12/1/05. No transition period of duplicate
readings was taken, so there is no way to know if the new monitor is
properly calibrated.
NA The South Lake Gauge Board was restored in December 2005. This
reading seems to be about 5 feet less than the lake monitors installed
by Luhdorff We are working on a way to get alternative readings
that
are
consistent with the historical record.
