Summary Report: Water Quality Characteristics
of Sligo Creek
December 2002
INTRODUCTION
October 18, 2002 was the 30th Anniversary of the enactment of the Clean Water Act.
This date marks a milestone in the efforts to protect our nation's water resources. This
anniversary also presented an excellent opportunity to:

Enhance public appreciation for the importance of our water resources,

Celebrate water quality improvements,

Build a better understanding of remaining challenges and solutions, and

Rekindle the public stewardship ethic and support for watershed protection
programs, and

Educate our nation's young people.
In support of these goals, Congress, along with a number of the nation's Governors and
national organizations have proclaimed 2002 as the Year of Clean Water. The America's
Clean Water Foundation (ACWF), a nonprofit 501(c)(3) organization created in 1989 to
coordinate the 20th Anniversary Celebration, is again serving as the primary sponsor and
national coordinator of the Year of Clean Water. ACWF coordinated a series of events
throughout October 2002 to commemorate the 30th Anniversary of the Clean Water Act.
In addition, government agencies and private organizations will also sponsor a host of
national and watershed specific events in support of the Year of Clean Water. These
events are designed to promote public involvement, provide education and outreach,
support technical exchange and document the status of water quality since the initial
passage of the 1972 Clean Water Act.
One event sponsored by ACWF was National Water Quality Monitoring Day, a
nationwide monitoring episode that occurred during a two week window around October
18th. This event provides a snapshot of water quality conditions across the Country. The
Friends of Sligo Creek (FOSC) coordinated a monitoring effort to participate in National
Water Quality Monitoring Day.
METHODS
Sample Station Selection. A total of 9 stations were established along the mainstem of
Sligo Creek. Three major tributaries—Long Branch, Takoma Branch, and an unnamed
tributary in the upper portion of the basin—were also sampled. A description of the
stations is provided in Table 1 while locations are shown in Figure 1.
Table 1. Sample station locations and descriptions1.
Site ID
SC1
SC2
SC3
SC4
SC5
SC6
SC7
SC8
SC9
LB1
LB2
LB3
Watershed
Location
Sligo Creek
mainstem
Sligo Creek
mainstem
Sligo Creek
mainstem
Sligo Creek
mainstem
Sligo Creek
mainstem
Sligo Creek
mainstem
Sligo Creek
mainstem
Sligo Creek
mainstem
Sligo Creek
mainstem
Long Branch
mainstem
Long Branch
mainstem
Long Branch
mainstem
Latitude/Longitude
Location Description
38° 58’ 22.74269”
76° 59’ 00.44635”
38° 58’ 24.08873”
76° 58’ 00.21088”
38° 58’ 51.17898”
76° 59’ 23.21362”
38° 58’ 51.01583”
76° 59’ 25.86480”
38° 59’ 43.91239”
76° 00’ 26.13654”
39° 00’ 39.94806”
77° 01’ 34.80996”
39° 00’ 49.40309”
76° 01’ 52.97376”
39° 00’ 37.28214”
77° 01’ 30.59476”
30 ft downstream from confluence with Takoma
Branch -8ft from right bank
50 ft upstream from confluence with Takoma Branch 10 ft from left bank
Downstream of confluence of Long Branch, ~250 feet
upstream of New Hampshire Ave.
~600 feet upstream of New Hampshire Ave., ~150
feet upstream of confluence with Long Branch.
100 ft upstream from Piney Branch Road bridge - 6 ft
from right bank
ND
ND
38° 58’ 53.85756”
76° 59’ 27.71693”
38° 59’ 13.05812”
76° 59’ 41.94755”
38° 59’ 56.14055”
76° 59’ 53.71048”
LB4
Long Branch
mainstem
39° 00’ 30.61364”
77° 00’ 08.14320”
TB1
Takoma Branch
38° 58’ 23.55780”
76° 59’ 01.91159”
1. ND = no data.
Dallas Ave at Sligo Creek Parkway
~75' below I-495 culverts.
Tributary below Parkside Bridge, ~100' below Dallas
Ave.
In Becca Lilly Park, ~480' us from Sligo Ck.
~150' upstream of Carroll Ave
~50' upstream of Piney Branch Ave
DS end of Upper Long Branch Park, on bedrock
outcropping near Wilmer and E. Melbourne, ds of
footbridge. 36" storm drain outlet on RB/DS.
Located 70' upstream from confluence with Sligo
Creek
Figure 1. Location of sample stations in the Sligo Creek watershed. Station SC 9 is not
included on this map.
Analytical Methods and Sample Collection Techniques. The following parameters were
analyzed during this sampling effort:





Dissolved Oxygen (mg/L)—amount of Oxygen present in the stream.
% Dissolved Oxygen Saturation (%)—amount of Oxygen that the water can hold,
controlled by temperature.
Temperature (deg. C)—temperature of stream, in degrees Celsius.
pH (units)—acidity of the water.
Water Clarity (JTU)—measure of the amount of cloudiness in the water.
The test kit used was the one offered for sale at www.yearofcleanwater.org produced by
the LaMotte Company, Chestertown, Maryland (www.lamotte.com) specifically for
YOCW sampling activities. Specific questions regarding the analytical procedures
should be directed to the manufacturer.
Samples were collected using the methods described in Appendix A and in the handbook
included with the test kit. These test kits involved adding reagents to a sample, then
reading the color of the sample by comparing the sample color to a card where colors
have been associated with known levels of a particular parameter. Occasionally,
observers interpolated between values if it appeared that the test result was between two
colors.
Quality Assurance / Quality Control. The following activities were performed to ensure
high quality data collection:




A coordinator was appointed to oversee the sampling work
A Standard Operating Procedure was developed and distributed to all participants.
This is reproduced as Appendix A.
Data were processed by the coordinator and examined for obvious errors. Any
questions were resolved by the coordinator.
For pH, a second test kit with greater resolution was used concurrently with the
YOCW kit to check the results. No significant discrepancies were observed
between the two kits.
RESULTS
A summary of the results by parameter is presented below. All data described below can
be found in Appendix B.
pH. The pH of Sligo Creek and the sampled tributaries ranged from a low of 6.75 to a
high of 8. Along the mainstem of Sligo, values ranged from 7 to 8 with an average of
7.8. In Long Branch, pH averaged 7.2 and ranged from 6.75 to 7.5. The lowest value
reported during this sampling event was reported in Long Branch. Finally, in Takoma
Branch, a pH value of 8 was observed. Figure 2 shows the distribution of pH values
throughout the watershed.
Figure 2. Distribution of pH values in the Sligo Creek watershed.
Dissolved Oxygen. Dissolved oxygen levels in Sligo Creek ranged from 4 to 8 mg/L.
Along the mainstem of Sligo Creek, values ranged from 4 to 8 mg/L with an average of 6
mg/L. In Long Branch, values ranged from 6 to 8 mg/L, with an average of 8 mg/L
observed. In Takoma Branch, a DO of 4 mg/L was observed. See Figure 3 for the
distribution of dissolved oxygen values.
Percentage of Dissolved Oxygen Saturation. The %DO Sat in Sligo Creek ranged from
a low of 37% to a high of 74%. Along the mainstem of Sligo Creek, values ranged from
37 to 74%. In Long Branch, values ranged from 56 to 74%. In Takoma Branch, a single
value of 37% was observed. Figure 4 shows the distribution of %DO values in the
watershed.
Turbidity. Within the Sligo Creek watershed, turbidity values ranged from 0 to 40
Jackson Turbidity Units (JTU). The average turbidity observed was 18 JTU. In Long
Branch, no measurable levels of turbidity were documented. A single value of 40 JTU
was measured in Takoma Branch. The distribution of turbidity values within Sligo Creek
is shown in Figure 5.
Figure 3. Distribution of Dissolved Oxygen concentrations in the Sligo Creek watershed.
Figure 4. Distribution of Percent of Dissolved Oxygen saturation in the Sligo Creek
watershed.
Figure 5. Distribution of Turbidity values in the Sligo Creek watershed.
DISCUSSION AND RECOMMENDATIONS
While past studies have documented impairment within the Sligo Creek watershed
(Millard et al 2001), no significant problems were observed in the water quality of Sligo
Creek during this sampling exercise. As part of a countywide study conducted by
Millard and others (2001), water quality sampling concurrent with biological sampling
was performed at one station within Sligo Creek in 1997. The biological community
rated very poor while habitat was scored as fair. Only two parameters measured during
this study were measured during that study and are reported below:
pH = 8.22
Dissolved Oxygen = 7.5 mg/L
In Sligo Creek, the average pH value observed was similar, but lower than, the one
observed previously. However, a pH of 7.8 to over 8 is higher than typically observed in
freshwater streams in Maryland. There might be something unique about the geology of
Sligo Creek that contributes to the basin having a higher pH.
Dissolved oxygen values were much lower in places along Sligo Creek than observed
Millard et al (2001). Values of below 5 mg/L are very rare in shallow, free flowing
freshwater streams. It is possible that the method used to evaluate dissolved oxygen was
not sensitive enough to accurately measure the parameter. It also possible that if samples
were taken in shallow pools instead of flowing areas, then DO values would be lower
than if taken from flowing water. DO values along Long Branch were on average much
higher, ranging from 6 to 8 mg/L.
Turbidity overall was very low, which is expected when sampling occurs during base
flow conditions. However, Sligo Creek becomes very turbid during storm events, so
turbidity is likely a significant water quality impairment within the basin. In addition,
regular inputs of turbid waters come from failing silt fences and other best management
practices on construction sites within the basin.
Based upon this work, the following recommendations are made:

Further investigations of pH should be made to determine the typical values found
within Sligo Creek.

Further investigations of dissolved oxygen should be made to determine if levels
are frequently at or below 4 mg/L or if this is an artifact of the test kit used during
this sampling event.

Test kits that are more sensitive and provide a greater range of interpretation
should be used for future chemical sampling.

Quality Assurance / Quality Control procedures should be strengthened.
Specifically, a practice and training session should be held for all FOSC samples
to ensure that interpretation of sample colors is standardized.

A comprehensive monitoring program—including biological, physical, habitat,
and chemical monitoring—should be implemented within the watershed to
understand overall ecological conditions within Sligo Creek.

A targeted monitoring program—focused on storm drain outfalls or some other
issue that is of importance to the membership of FOSC—should be considered.
REFERENCES
Millard, C.J., P.F. Kazyak, and A.P. Prochaska. 2001. Montgomery County Results of
the 1994-1997 Maryland Biological Stream Survey: County-Level Assessments.
Produced by the Maryland Department of Natural Resources, Resource Assessment
Service, Monitoring and Non-Tidal Assessment Division. Annapolis, MD, 21401.
Appendix A
Coordination Email and Standard Operating Procedures for YOCW Sampling Event
Coordination Email:
Greetings!
As many of you know, FOSC is planning a water quality monitoring event on or about 18
October. This monitoring is being done as part of the nationwide commemoration of the
Clean Water Act’s 30th anniversary. Water quality data are being collected nationwide in
order to get a snapshot of conditions in waterways across the country. Many federal,
state, and local governments are participating along with many non-profits and watershed
groups like FOSC. For example, the Maryland Water Monitoring Committee, a state
water quality umbrella group, is collecting the data for the entire state—including
FOSC’s contribution—and will put it up on their website. For more information, go to
www.yearofcleanwater.org for additional details.
What FOSC Will Do:
FOSC members will collect water quality samples at a handful of sites along the Sligo
Creek mainstem and its major tributaries. The following things will be tested:
pH. A measure of water acidity. Pure water has a pH of about 7. Seawater has a pH of
about 8.1. Freshwater streams in Maryland typically have pHs ranging from a little over
6 to a little over 7. Critters get stressed out starting at about 5.5. Most critters are gone
below 4.5.
Dissolved Oxygen. A measure of the amount of oxygen carried by the water. DOs
below 5 mg/L mean big trouble for critters while those above 5 mg/L mean things are ok.
DO varies with time of day since it is related to photosynthesis. Flowing waters in
Maryland typically have DOs in the 7 to 10 mg/L range.
Temperature. Temperature directly impacts aquatic critters and impacts water quality
attributes of streams. Urban streams typically have elevated temperatures after storm
events as rain water is heated up as it flows over pavement before it enters streams.
Temperature is highly variable in Maryland streams, but generally follows seasonal
trends (goes up in summer, down in winter).
Turbidity. A measure of water clarity. Sediment from stream bank erosion,
construction site runoff, and other sources raises turbidity levels. High turbidity impacts
all stream critters adversely. High sediment is one of the most persistent pollution
problem facing Maryland streams. Unless it rains a day or two before the 18th, the water
should be fairly clear (0 to 40 JTU).
Where and When to Test:
In general, we should try to cover most major road crossings and the confluences of all
major tributaries (Wheaton Branch, Long Branch, etc.).
The official anniversary of the Clean Water Act passage is 18 October. It is possible that
this will not be very convenient for everyone as this is a Friday. In addition, the actual
window for the national dataset spans a 10 day period around the 18th. So, to make it
easier for everyone, the window for data collection starts on Friday, 18 October and
continues through Sunday, 20 October.
The following areas are being covered by various members of FOSC. I don’t know
everyone’s name, so I might yours wrong. Also, I am not as familiar with the watershed
and the tributaries as many of you. Please drop me an email if you have questions or
corrections to this list:
Mainstem Stations:
1. University Avenue—Kathy Michels
2. Colesville Road—Ross Campbell
3. Maple Avenue—Jane Harman
4. Carroll Avenue—Steve Shofar
5. Confluence with Long Branch—Chris Victoria
6. East-West Highway—Ann K(?)
Tributary Stations:
1. Long Branch at Becca Lilly Park—Chris Victoria
The following areas are not covered at the present time:
Mainstem Stations:
1. Wheaton area headwaters
2. Forest Glen Area
3. Piney Branch Avenue
Tributary Stations:
1. Wheaton Branch
2. Takoma Branch
Others?
If you wish to sample an area, send me an email and let me know where your sampling
location will be. To avoid duplication of effort, I will be coordinating the assignment of
stations, so drop me a line if you want to cover one of the areas listed above or wish to
sample somewhere else. I can be reached at christopher_victoria@yahoo.com, or at
410.222.7441 during business hours or at home at 301.439.3930.
Getting the Materials to Do the Work
The sampling is pretty easy. Not counting travel time, the actual testing should take
about 20 minutes. The test kits we plan to use can be obtained at
www.yearofcleanwater.org. Just follow the link that deals with National Water Quality
Monitoring Day for ordering information. A limited number of kits have already been
ordered. I am happy to share my kit with you if you’re willing to pick it up. However, if
you want to practice the tests using tap water, you should try and order your own.
How to Do the Work
Attached to this email is a document that describes how you should do this. If you have
any questions, drop me a line.
I’ve done the sampling, now what?
Send me the original data sheet. Mail it to:
Chris Victoria
1104 Merwood Drive
Takoma Park, MD 20912
I will produce a summary of the information and provide it to Sally so that she can send it
out to the members. I will also make sure that it gets on the national website and to the
state people.
SOP begins here:
How to Do the Sampling Work
You will need to bring the following items with you to the stream:
1. The test kit and its instructions along with this guidance document.
2. The data sheet to record your results (see below)
3. A pencil or pen. A clipboard is nice to hold your data sheet, but is not required.
4. A stopwatch or a wrist watch with a second hand.
5. A container to dump out the tests when completed. A zip lock bag would work
well for this.
6. Rubber gloves (optional) or waterless hand cleaner (also optional, but suggested).
General Guidelines:
The kits are easy to use and come with complete instructions. If you have a fish tank, the
tests are very similar to the ones you’d use with your tank. The following modification is
made to these instructions:

Don’t bother boiling a test container. Collect the sample directly into the white
test kit container, rinsing the container first as described in the instruction booklet.
Then do all your tests at the stream using the water you collect in the white
container.

Dissolved oxygen is technique sensitive. Follow the instructions closely,
especially regarding the timing of the test.

Unless you have a compromised immune system, Sligo Creek at low flow
conditions is not so nasty as to warrant rubber gloves during testing. Just wash
your hands after you get home and don’t eat or prepare food until you do.
However, if you feel more comfortable, wear gloves if you wish.
Except for the advice about rubber gloves, follow the other safety tips listed in the
booklet. In particular, DO NOT SAMPLE THIS STREAM DURING A
RAINSTORM. You could be killed by rising flood waters. Streams like Sligo can rise
several feet in a few minutes during a heavy downpour. Additionally, the water becomes
much more polluted during storm flow conditions, making it hazardous to handle.
Remember, this isn’t worth dying over. We will try and reschedule if it rains during the
sampling period.
A data sheet is included as part of this write up. Please fill it out completely as you work.
It’s good to have a helper so that one can record the numbers while the other does the
tests.
Selecting a sample site:
1. If you are sampling at a road crossing, sample upstream of the bridge or culvert.
No need to sample up and downstream.
2. If you are sampling at a tributary near the Sligo mainstem, try to sample 5 to 10
tributary channel widths upstream of the confluence. But do your best. If it’s dry
there, go to where flow is occurring. If it’s totally dry, note that on the data sheet.
3. At tributary confluences, sample up and downstream of the confluence. Use a
separate data sheet for each location
4. Pick a site that is easy and safe to access. Watch your step!
5. Stand on the stream bank and look upstream. Sample in an area that is
representative of what you can see. If it is all fast moving water, sample there.
Don’t sample outfalls, obviously bad places, or other odd conditions unless it is
typical of the stream overall. We can sample bad places on purpose another time.
We’re trying to characterize typical conditions today.
6. Take a picture facing upstream from the place where you do the sample
(optional).
Getting the sample and doing the work:
1. Follow the instructions in the booklet and the method modification in the General
Guidelines above.
2. Once you collect the water sample. Do the work in the following order:
Turbidity
Temperature
Dissolved Oxygen and %DO saturation
pH
3. Write down the results on the data sheet.
4. Fill out the sheet completely. No blanks please! If you have blanks for some
reason, please mention why in the notes section on the bottom half of the page.
5. Try to precisely describe the sample site location. Use a GPS unit if you have
one. Don’t say “Upstream of Piney Branch.” Say “Site is located approximately
45 feet upstream from the upstream side of the bridge at Piney Branch Avenue.”
Remember, somebody other than you might have to sample this site again next
year. Be descriptive!
6. Dump the tests into your container and dispose down the sink at home.
Friends of Sligo Creek Water Quality Monitoring Data Sheet
Date/Time:__________/__________
Weather Conditions:__________________
Sample Crew:______________________
Rain in last 24 hours?__________
Station
Location:________________________________________________________________
________________________________________________________________________
TEST RESULTS:
Turbidity (JTU):_________________
Temperature (deg C):____________
Dissolved Oxygen (mg/L):______________
% DO Saturation*:________________
* From p.11 in Test Kit instructions. Leave blank if you don’t have the booklet.
pH:_________
NOTES (describe any unusual conditions about the site, the tests, etc):
Appendix B
Original Data