McKownville
Improvement Association
- groundwater variations north of Western
Avenue
Record of groundwater level from only one monitored
well
The groundwater levels in McKownville fluctuate, depending on rates
and amounts of precipitation received, and of surface runoff,
evaporation, plant and tree transpiration, and flow in the
unconfined sand aquifer to the local creeks. While there are a few
private wells in the area, the overall amounts extracted and the
effects of these are likely to be small; the University claims not
to be extracting any groundwater for the fountains or field
irrigation. Because there is only one monitoring well in the area
with a long-term and reliable record, there are limits on what can
be concluded as to the relative influence of all possible causes of
the fluctuations. The record for this USGS well A-654 near Alumni
House on the University at Albany campus suggests that local
precipitation, and its infiltration, is usually the major control,
but there are obvious large anomalies at some times in the record
that can not be explained simply by direct precipitation
infiltration as a prompt input.
Spring to fall drawdown
Looking at the record of the most recent year (2024) as a starting
point, it contains an excellent example of significant and
consistent drawdown of the water table from late spring (mid-April)
to later summer (early August); from a high of around 5.8 feet below
the surface, to a low of about 8.7 feet below. There are three small
reversals in this interval lasting a few days, directly caused by
precipitation events, one in early May, and three events in June;
these are rises of 0.04, 0.04, 0.21, and 0.03 feet (0.5, 0.5, 2.5,
and 0.4 inches) over 1 to 3 days, after which the steady drawdown
resumes. Precipitation for these four events was 1.24, 1.56, 1.33,
and 0.46 inches recorded at the Albany airport weather station;
there was a lot more rain locally in the third event as there was a
deluge associated with a thunderstorm and this caused significant
flooding on Western Avenue at Fuller Road. Mike Wren's records from his
McKownville.com weather station give precipitation of 1.12,
2.38, 3.81, and 0.53 inches for these events.
What happened in August? From 2 to 9 August 5.7 inches of rain fell
at the airport (7.17 recorded in McKownville), with more than 3
inches of this total in the last two days of this interval. Based on
the smaller events earlier in the year, perhaps 6-7 inches rise in
the water table might perhaps be thought predictable. But the rise
was much larger, 1.12 feet, about double the amount of local
precipitation. Another significant precipitation event occurred
18-19 August, with local precipitation of 2.2 inches recorded at the
airport (4.15 inches in McKownville); the water level in the well
rose 0.47 feet (5.6 inches) over the next four days. Then, the
summer drawdown resumed, in the absence of any further substantial
precipitation, the rate declining into October as average air
temperatures, and transpiration from trees, decreased.
So here is evidence that the infiltration to the local aquifer near
the well is not simple; during large precipitation events the water
table can rise by amounts much larger than would be expected from
just direct infiltration. As to what source(s) are providing the
excess water, these must be nearby, since the response is swift,
within a day or two of the precipitation event. Runoff flow ponding
near the well seems the most likely possibility, but overflow from
nearby drain systems (including infiltration storage installed
during recent apartment construction, and reconstruction of nearby
University roadways) might also be a source.
Water depth record for 2024 to 28 November in USGS monitoring well
A-654 near Alumni House on the SUNYA campus
well depth charts and data on this page sourced from:
https://waterdata.usgs.gov/nwis/uv?site_no=424115073495301&legacy=1
Water depth record for the interval 2010-01-01 through 2024-11-27 in
USGS monitoring well A-654 near Alumni House on the SUNYA campus
showing the range of water table depth variations over this 14 year
interval, from a maximum depth of nearly 12 feet to a minimum of
near 5.5 feet.
Fall to spring recharge
Most of the yearly records show a rise in the water table from late
fall or early winter to the spring of the next year, the primary
causes being low evaporation during the interval of low surface
temperatures and no significant transpiration by trees and other
vegetation. This can be seen in the multi-year record on the graph
above. The amount of recharge varies; for instance the decline in
maximum, minimum, and average well depths from 2011 through 2016
corresponds to generally lower than average overall precipitation,
and the general increase since then (except for 2020 and 2022) to
increased overall precipitation. To support this conclusion, the
charts below show the 6-monthly interval precipitation records since
the year 2000, and the minimum and maximum water depths in the
monitoring well record for these two time intervals each year.
The more detailed pattern for a single recharge season,
however, seems not to be strongly correlated with individual
rainfall or snowmelt events and also is in most years substantially
larger in total amount than the overall precipitation during that
interval. So there must be sources upslope (up hydraulic gradient)
from the well for this excess groundwater supply.
Where are these? The map below shows the area and local topography
with 2ft contour interval, showing a small area to the north, where
dormitory accommodation is located, may be part of the source,
although this area slopes significantly away along its northwest and
northern sides, so only a part of it might influence the well
recharge. The other area slightly above the well elevation occurs
west of Fuller Road, and being of greater extent, is more likely to
be the major source.
The nearby wetland north of the western parts of Mercer and Warren
Streets indicates that there is a perched water table in this area,
on a thin clay layer within the sands. Underground, non-uniform
spillage to the east from the edge of this feature might provide a
reason for a complex recharge pattern at the monitoring well. The
flow from this possible source would cross through the site of the
new large apartment blocks at the west side of Fuller Road, and the
construction of the foundations of these large buildings, and
infiltration storage under the parking areas, could have made
significant changes to the groundwater flow compared with the
situation of the previous low-density residential use of this area.
map of west SUNYA campus area and adjacent McKownville
showing local watershed lines and inferred general groundwater flow
directions
base map sourced from Town of Guilderland online Interactive
Mapping site:
https://ny-guilderland.civicplus.com/398/Town-of-Guilderland-Interactive-Mapping
[topographic contours at 2 ft interval on this map were
derived from lidar imaging]
return to McKownville groundwater
page