Request

The Preserve Lake Dunlap Association Asks New Braunfels to Remove Phosphorus from their Wastewater Treatment Plant's Effluent Released into Lake Dunlap.

Recently, PLDA mailed letters to the City Council members and the NBU Board Members with the purpose of educating them on Lake Dunlap's water quality problems. The following is just some of the information that was sent out.

The Preserve Lake Dunlap Association (PLDA) is very concerned about the amount of nutrient loading into Lake Dunlap from the New Braunfels wastewater treatment plant (NB WWTP) and the algae problems this is causing in the lake. “Nutrient loading” usually refers to nitrogen and phosphorus entering a river or stream. Spring water in Central Texas is rich in nitrogen; therefore the Comal has a lot of natural nitrogen. When phosphorus is added to nitrogen, a perfect fertilizer is created, causing algae blooms to occur.

Sources of phosphorus can include fertilizers, soil and human or animal waste. There is plenty of documentation to substantiate that nitrogen enters Lake Dunlap naturally from the Comal River, and we regret to inform you that large amounts of phosphorus is discharged from the NB WWTP.

Eutrophication is what scientists call it when increased nutrients cause lakes or rivers to have an overgrowth of plants (macrophytes) or algae (microphytes). Algae is measured by scientists, by measuring the amount of chlorophyll in ug/L or milligrams per Liter. Lake Dunlap is now considered “eutrophic” and reaches “hypereutrophic” levels of chlorophyll in summer according to recent studies conducted by GBRA.

A recent study, commissioned by GBRA and conducted by Dr. Allen Groeger from SWTSU throughout the years 2000-2001, has not been release for publication yet. Our organization (PLDA) also commissioned Dr Groeger over the summer of 2001 and a summary of his work over the summer is attached. His work focuses primarily on nutrient loading and the affect water temperature, water flow, and other factors have on the eutrophication of a lake (in the case of Lake Dunlap, the increase of microscopic algae or phytoplankton).

With Lake Dunlap having been studied so extensively over many decades, the Preserve Lake Dunlap Association respectfully asks why nothing has been done to correct Lake Dunlap's eutrophic condition? It has been conclusively shown that phosphorus is the limiting nutrient affecting aquatic plant and algae growth and that the NB WWTP is the “point-source” contributor of phosphorus entering into Lake Dunlap.

When the PLDA asked recently whether NBU had any plans to remove phosphorus from their WWTP, Mr. Biggers stated that the study done in 1998 stated that due to the phosphorus in the sediment, tertiary treatment would not eliminate the macrophyte problem Lake Dunlap was experiencing. Therefore, it would not be cost effective. However, the same study stated that “reducing point source P concentrations down to .5 mg/L, which is about as low as technically achievable with tertiary treatment, would reduce the peak chlorophyll (a measure of algae) as much as 60%.” Plus, the studies done by Wright and McDonnell observed that water concentrations of phosphorus affect sediment concentrations. Lake Dunlap's macrophyte (hydrilla) problem is currently under control due to the introduction of grass carp. Lake Dunlap's microphyte (algae) problem is due to phosphorus in the water, not sediment.

Some would suggest eliminating phosphorus detergents from the market, but most laundry detergents sold now are phosphorus-free, because so many communities have realized that they need to protect their waterways. The cities of San Marcos, Kerrville, Comfort and Austin all felt tertiary treatment was well worth the cost to protect their precious water source. Lake Dunlap literally is the “water source” of thousands of people. The Canyon Regional Water Authority pumps water directly from Lake Dunlap to supply Crystal Clear, Green Valley and Spring Hill.

Our intent was to help bring information to you to better educate you on the reasons for Lake Dunlap's water quality problems. For those of us who see it every day, Lake Dunlap has not been a healthy lake for many years. During the summer months, it becomes quite eutrophic. The algae blooms vary depending on flow, temperature, rainfall, etc. Lake Dunlap cannot depend on flow to “handle” the nutrient loading. Droughts or even short dry spells can severely affect flow. Even in a year with average rainfall, Lake Dunlap still turns green throughout the summer. The following are statements from the attached letter sent by biologist, Dr. Allen Groeger:

Sept. 2001

The eutrophication in Lake Dunlap has been greatly accelerated by releases from the North and South Kuehler NBU wastewater treatment plants. The addition of phosphorus to Lake Dunlap stimulates the growth of algae. Eutrophication degrades the water quality in a number of ways, including:

• The increased phytoplankton reduce the clarity of the water, an important aesthetic value of a river or lake.
• The increase in algae and or large macroscopic plants leads to a depletion of oxygen when the algae and plant material decomposes. This can have an impact on the fish and other organisms living in the water.
• The phytoplankton such as algae commonly cause taste and odor problems in the water and under extreme conditions, diarrhea or allergies.

In conclusion,The Preserve Lake Dunlap Association is confident that New Braunfels Council and the NBU Board will want to implement tertiary treatment now that they have all the information about the harm the phosphorus is causing to those who live just downstream. Lake McQueeney and Lake Placid lakeside landowner and protection groups have expressed their support for our efforts to improve the water quality of Lake Dunlap. NBU General Manager, Paula DeFanzo and water and sewer manager, Roger Biggers have been notified of our intentions to protest any future discharge permits or expansions until New Braunfels makes the commitment to implement tertiary treatment. PLDA is confident we would win a contested case hearing based on the history and experience of the San Marcos contested case hearing on the subject of phosphorus. The city of San Marcos spent money on legally fighting the San Marcos River Foundation that could have spent on implementing tertiary treatment.

Because we believe New Braunfels would be more reasonable and responsible if fully informed of the reasons for phosphorus treatment, we hope to avoid such a costly legal battle that results in a lot of negative publicity about water quality. We believe the citizens of New Braunfels, like the citizens of San Marcos, will think it is worth the small cost of phosphorus treatment to preserve the Guadalupe River that brings so much pride to this community, is the basis of a large tourism industry, and serves as the primary water source for thousands of people.

If any one would like more information on the studies conducted on Lake Dunlap, you can access their bibliography information from the same source we used. Go to Back to Articles and read the 1998 study “Analysis of Aquatic Plant and Nutrient Conditions in Lake Dunlap.” PLDA request all its members to fill out the form letter provided in this issue and mail it to City Council Members and NBU Board of Trustees. There has to be enough public interest for them to take an interest. So please, take time to make copies of the letter and mail them. We encourage you to add to it anything you would like to say about the water quality of Lake Dunlap. If you have any questions, you can contact the Chairperson of the Water Quality Committee, Terri Hannasch at 606-3909 (home) or 660-4961 (cell phone).