2017 Big Spring Monitoring Data

Master Naturalist Carrie Robinson conducting dissolved oxygen testing at Big Spring 2017

The Texas Stream Team is based at Texas State University and is affiliated directly with The Meadows Center for Water and the Environment. The Stream Team is a partnership of agencies and trained volunteers working together to monitor water quality and educate Texans about the natural resources in the state. Established in 1991, the team is administered through a cooperative partnership with Texas State, the Texas Commission on Environmental Quality (TCEQ), City of Dallas and the Environmental Protection Agency (EPA).

Big Spring has two data testing sites in conjunction with the Texas Stream Team. The sites are #80939 Big Spring Source at the contact horizon where the water first surfaces and #80965 Big Spring Crawfish Pond some 70 feet west from the source.

Data has been collected from 2013-2017 by Master Naturalist Richard Grayson, Texas State University Student Alexander Neal, Master Naturalist Carrie Robinson and Master Naturalist Ben Sandifer, who serves as primary tester at site. Big Spring’s water team includes many faces. A thanks to all for their hard and often unrewarded work in this arena.

Basics:

-Texas Stream Team has been monitoring monthly since June 2013

-Big Spring is the only natural spring in North Texas monitored for both E.coli and flow on a monthly basis.

-Test sessions at two sites numbered 80939 and 80965. Data available online at Texas Stream Team website:

Big Spring Source:

https://aqua.meadowscenter.txstate.edu/events.aspx?qrySite=80939

Big Spring Pond:

https://aqua.meadowscenter.txstate.edu/events.aspx?qrySite=80965

-Monthly chemistry testing including E.coli protocols

-Average time in the field plus labwork is 3 hours per person, per month. It is a labor intensive and time intensive activity. In 2017 the 1000 volunteer hour milestone was reached at Big Spring for Stream Team water testing.

Water temperatures at Big Spring vary little at Station 80939 and 80965. These measurements are taken directly from the spring water itself. Ambient air temperatures during testing have varied from 102 degrees in August to 23 degrees in February.

Station 80939(Big Spring Source) which is the direct water source from the ground at Big Spring reflects a temperature similar to that of the average annual temperature in Dallas, Texas of 66.9 degrees. Big Spring averages 65 degrees year round. This water features high conductivity, low dissolved oxygen and a near steady 6.7 pH. This information suggests a high residency time of the water in the ground.

Station 80965(Big Spring Crawfish Pond) which is 70 feet from the source is exposed to the atmosphere and is a water column that passes through a wide array of aquatic plants and life before being tested. Residency time of the water in the pond is rather short as it moves through the outfall. Water exposed during the extremes of atmospheric temperatures can be impacted to some extent.

Trained Volunteers from the Texas Stream Team have been monitoring the quality of the Trinity River and water in tributary streams of the White Rock Creek watershed in Dallas since January 2005. Monthly monitoring at Big Spring began in June 2013 with a protocol of chemistry and E.coli testing.

E. coli Testing at Big Spring Site #80965

Big Spring’s Crawfish Pond site 80965 is tested for E.coli by collecting a water sample from the pond 1 meter off the bank in the middle of the pond. Results from 2013-2017 varied wildly in E.coli colony forming units “cfu’s”. The amount of animal activity around the spring was the direct contributing factor to elevated E.coli numbers. A number of animal species reside in and around the spring site which add E.coli and other bacteria to the water column. The water quality remains very good unless feral pigs migrate into the spring complex.

We are using the single water sample threshold for the EPA threshold levels noted in the graph. There is a lower cfu number for contact thresholds but is based on a 30 day mean. For example, in freshwater environments, 126 cfu (colony forming units) is the threshold for immersive human contact versus the 235 cfu for single sample testing for the same standards(see graph). Please note geometric mean calculation on graph as well.

Feral hog activity as evidenced by heavy rooting in and around the spring pond site was the direct contributor to high numbers of E.coli colonies at Big Spring’s 80965 test site over three years. High counts all reflect feral pig activity around the spring site.

 

Flow Data

Big Spring’s flow rate is calculated at the outfall of a pvc pipe located 75 feet from the spring source. The spring waters flow out of at least four known sources and aggregate in a pond/pool below. Measurements are taken below the aggregation point using a 4 or 5 gallon bucket. Timing is done with a stopwatch in a series of three timed tests with averages obtained at the end. That number is cross-referenced to the chart above with gives flow.

The spring contributes 11.5-14 million gallons of water into the watersheds of White Rock Creek and the Trinity River Basin annually. Big Spring is classified as a Magnitude 5 spring which discharges 10-100 gallons per minute.

2015 and 2016 saw above average rainfall totals for the Dallas area. That increase in rainfall appears to have a positive effect on the discharge from Big Spring as evidenced in the data. 2017 saw an average year for rainfall and as a result the discharge has fallen a bit. When monitoring at Big Spring began in 2013 Dallas County was recovering from a prolonged dry spell of record. Data suggests that is reflected in the lower discharge in 2013.