Emails (excerpted), responses to PolitiFact Texas, Andrea Morrow, spokeswoman, Texas Commission on Environmental Quality, Jan. 9-10, 2013
Jan. 9, 2013
Here’s the summary. This answer is compiled from staffers in TCEQ’s Wastewater Permitting and Surface Water Quality sections.
Ok, there are six water quality parameters or constituents that are directly comparable (Austin treated wastewater effluent vs. lake water near surface water intakes). I’ve attached a spreadsheet that summarizes data from Austin’s seven wastewater treatment plants and shows corresponding data from a composite of surface water quality data from areas around the City’s surface water intakes on Lake Austin (2) and Ladybird Lake (1). The effluent data is recent and is collected in a controlled environment, the lake data is a composite over a ten-year period based on “snapshot” sampling. There is a lot more variability in nature.
Here’s how they compare:
total suspended solids (TSS)
This can be thought of as a measure of water clarity. On average, the effluent had lower TSS (better clarity).
Form of nitrogen that can be toxic to aquatic life in high enough concentrations but more typically serves as a nutrient for plant and algae growth. Effluent had higher concentrations than the lake water.
total phosphorus (TP)
Another nutrient needed for plant and algae growth. Too much can potentially over-stimulate growth. Only two of the Austin treatment plants monitor phosphorus, and the effluent had higher concentrations.
Measure of how acidic or alkaline the water is (scale of 0 to 14). Generally want to be in midrange without extremes. Both effluent and lake water were in reasonable ranges.
Breathed by fish and other aquatic organisms. Effluent and lake values are acceptable. Low levels can naturally occur at/near the bottom of lakes (zeroes in the lake data minimums), but raw drinking water is not drawn from that depth generally.
Type of bacteria used as an indicator of water quality. Found in the intestinal tract of warm-blooded organisms, it’s presence can indicate fecal contamination and the potential for waterborne disease. The effluent generally had lower E. coli numbers.
These are only a fraction of water quality parameters that could potentially be compared between the two water types, but the reality is that available data allows only a handful to be evaluated. With the parameters above, the effluent tends to be clearer and lower in bacteria levels, while the lake water is generally lower in nutrient concentrations. Dissolved oxygen and pH were comparable between the two types. So with respect to the statement that the effluent quality is higher than the source water, for some things it’s true, for others it’s not.
TCEQ Media Relations
(From PolitiFact Texas)
A water utility official tells us that according to Texas Surface Water Quality Standards, Lake Austin and Lady Bird Lake are rated “high” quality segments of the river, while the section downstream where Austin discharges most of its wastewater is rated more highly, as “exceptional.” Can you confirm this? Where would I find such information?
Jan. 10, 2013
Yes, this is correct. In the Texas Surface Water Quality Standards (Title 30 Texas Administrative Code Chapter 307), Lake Austin (segment no. 1403) and Lady Bird Lake/Town Lake (segment no. 1429) are assigned a high aquatic life use. The segment downstream of Lady Bird Lake, Colorado River Below Lady Bird Lake/Town Lake (segment no. 1428), has an exceptional aquatic life use designation. These designations can be found in Appendix A of the water quality standards under the Colorado River Basin (Basin 14). One place on our website to look at the current 2010 water quality standards rule (not all of it has been approved by EPA, but the segment uses referred to above have been approved) is the following:
Or, you can look up the Texas Administrative Code on the Secretary of State’s website here:
As to your other questions—
Frequency of monitoring at wastewater treatment plants is determined by the output. Major plants, defined as one million gallons per day or more of discharge are required to sample daily. Smaller plants may be twice a week, once a week and so on based upon their discharge rates. This schedule is spelled out in code here:
From: Selby, Gardner (CMG-Austin) [mailto:firstname.lastname@example.org]
Sent: Thursday, January 10, 2013 1:08 PM
To: Andrea Morrow
Subject: RE: Follow-ups and more
Do the six elements you laid out play into the water-quality determinations for different lake segments?
W. Gardner Selby
Jan. 10, 2013
This is probably more detail than you want but here goes:
Dissolved oxygen, E. coli, and pH are some of the primary parameters that are assessed when determining whether a major water body (classified segments in the water quality standards), lake or otherwise, is meeting its water quality standards. That’s because there are numeric criteria or standards on the books that monitoring data can be directly compared to.
Nutrients like ammonia-nitrogen and phosphorus are also important parameters in water quality assessments, but until we have EPA-approved numeric criteria for nutrients or some surrogate, it’s harder to make a determination of standards attainment and thereby use compare data to more informal screening levels. TCEQ has proposed chlorophyll-a (a measure of the density of microscopic algae – an indicator of level of nutrient enrichment) criteria for many major reservoirs in the state, but EPA has not yet granted approval. So the five of these parameters usually play into water quality determinations.
The remaining one, total suspended solids, is a more traditional parameter used in wastewater quality assessments.
TCEQ Media Relations