Interview with Hydrologist Raymond Slade

“Threats To The Texas Hill Country From Wastewater Discharges”

Interview with Certified Professional Hydrologist Raymond Slade, Jr.

for the No Dumping Sewage (NDS) campaign

Raymond Slade, Jr. is a Professional Hydrologist who has been deeply involved with Texas water issues over the past 45 years, first as a Hydrologist for the U.S. Geological Survey (USGS), then later as Hydrogeologist for the Edwards Aquifer Research and Data Center, and most recently as a consulting Hydrologist and volunteer for many environmental causes. He is intimately familiar with Texas Hill Country wastewater issues and contributed to the opposition of the contested Belterra wastewater permit application as well as the Dripping Springs wastewater permit application. He also teaches a class in water-resource data collection and analyses at Austin Community College and has published about 140 reports on Texas water science. We sat down with him to talk about current wastewater issues in the Texas Hill Country.


NDS:  There’s a lot of focus right now on wastewater discharge issues in the Texas Hill Country. Can you explain why the Hill Country is more vulnerable to contamination from wastewater direct discharge than the remainder of Texas?

Slade: There are a number of reasons. In general, relatively high permitted levels for contaminants in wastewater are allowed under Texas state law because nutrients (nitrogen and phosphorus) and other contaminants are expected to be absorbed in the waterway.  Outside the Hill Country, many streambeds contain vegetation and soils which absorb nutrients and other effluent pollutants. Additionally, such streams have flat slopes which reduce stream velocity. That provides time for pollutants to be absorbed before reaching downstream critical areas. Finally, any pollutants recharging non-Hill Country aquifers move very slowly and are absorbed by the soils in aquifers outside the Hill Country.

The Texas Hill Country however, compared to the remainder of Texas, has stream channels with 1) little if any vegetation or soils, 2) steep slopes and 3) extensive faults, caves, and springs. These conditions cause minimal if any absorption of wastewater contaminants. Also, effluent in Hill Country groundwater moves very rapidly and thus can pollute well water. For example, dye injected at the Dripping Springs proposed effluent discharge site on Onion Creek was detected at several wells within a few days.


NDS:  How do you think wastewater discharge permitting should be changed in order to better protect receiving waters?

Slade:  There are a multitude of changes that need to be made, in my opinion, due in part to the tremendous growth in the Texas Hill Country:

  1. Where feasible, decentralized wastewater treatment and reuse of wastewater should be encouraged and used.
  2. Decrease maximum allowable limits for levels for wastewater quality constituents
  3. Add additional water-quality constituent limits such as allowable Phosphorous, Dissolved Oxygen, and Total Organic Carbon (TOC)
  4. Wastewater plants shouldn’t receive prior notice of inspections from the Texas Commission on Environmental Quality (TCEQ), as they currently do. Time periods allowed for noncompliant operators to become compliant should be reduced to days rather than weeks. Fines and penalties for noncompliance should be imposed, rather than issuing multiple written warnings. Finally, notice of all violations, fines, and penalties should be made immediately available to the public via the web.
  5. Wastewater permit applications should include a thorough assessment for impacts on downstream water quality conditions, especially for those containing critical water areas.
  6. Establish a ban or limit on detergent phosphates (which cause eutrophication/algae growth) for Hill Country areas. Austin banned phosphates in detergents many years ago, but it is still allowed elsewhere.
  7. Require periodic water-quality monitoring of streams and aquifers downstream from wastewater discharges.
  8. Allowable wastewater contaminant levels should be established for grab samples (instantaneous value at time of sample), and 7-day average values, not just for 30-day average values


NDS:  If more stringent rules regarding wastewater permitting are not applied through legislation, how long do you think it would take for most hill country waterways to experience eutrophication/heavy algae growth?

Slade:  It’s already happening. In 2005-06, the US Geological Survey evaluated nutrient and biological conditions in 15 small streams in the Hill Country. Streams that did not receive wastewater effluent had relatively low nutrient concentrations and corresponding algae levels. Streams receiving wastewater effluent had relatively high nutrient concentrations and were classified as eutrophic. That report is available at


NDS:  If legislation isn’t passed with more stringent rules, how long before our drinking water supplies would be adversely impacted?

Slade:  Individual wells and groundwater would be impacted sooner than surface water supplies (i.e. Canyon Lake and the Highland Lakes) which rely on dilution from large water volumes. We are at the point now where there is a real threat to folks in central Texas who obtain their water via wells. The problem is that direct discharge is the cheapest and easiest method to dispose of wastewater, so that’s what many developers and municipalities want – even though it presents the greatest threat, especially to groundwater, for all the reasons stated previously.


NDS:  Why should the average person in central Texas care about excessive wastewater discharge into waterways, especially if they don’t ever use these waterways?

Slade:  They might not use the waterways, but if they live in the Hill Country, they likely drink water from sources which could be adversely impacted by wastewater effluent. Also, many pharmaceuticals, personal care products, surfactants, various industrial additives and numerous organic chemicals exist in wastewater.  None of these pollutants are addressed by TCEQ for wastewater permits, but many pose direct threats to human health.


NDS:  What do you think is causing the excessive algae levels we’re seeing this year in the South Fork San Gabriel River versus previous years, which still resulted in algae but not at these levels?

Slade:  Earlier this year, the wastewater effluent discharge for Liberty Hill was increased from 400,000 gallons per day (gpd) to 800,000 gpd and will soon expand to 1.2 million gpd, a threefold increase. The typical flow of the South San Gabriel isn’t high enough to absorb this extra wastewater without causing eutrophication of the river.


NDS:  If you were a property owner along the South Fork San Gabriel River, what action would you be taking (if any) right now in order to minimize the threat of algae and eutrophication in the river?

Slade:  Individuals who oppose the polluted South Fork San Gabriel should organize into groups, visit and write letters (with photos of algae) to political officials and ask television news stations to cover the story.   Corrective action often is given to issues identified in the news.  I understand some of these local residents are working with the NoDumpingSewage campaign, which is a positive step.