LCRA - Energy • Water • Community Services
 
Monthly Water Quality Report
Current Water Quality Conditions
April 2013

In April, most of the data for the index were provided by LCRA staff. Because LCRA staff no longer measures transparency in streams, transparency data for river sites were contributed by the Colorado River Watch Network, a group of volunteers who help monitor the waterways of the lower Colorado River watershed in Texas. Seven of 15 lower Colorado River basin monitoring sites earned excellent scores. Dissolved oxygen concentrations and water temperatures were optimal throughout the basin. Two sites, San Saba River and Lake Marble Falls, received poor scores that were attributable to rainfall runoff increasing the bacteria concentrations. The other Highland Lakes sites and upper basin tributaries earned excellent scores.

Results were mixed for the Colorado River downstream of Austin. The Columbus site received an excellent score. Downstream of Austin, however, nitrate concentrations were elevated and caused two sites – Bastrop and Smithville – to receive only good marks. The nutrient concentrations at these two sites were elevated but less than what was measured in March because flows were greater in April. La Grange earned a fair rating. The two sites nearest the bay, Wharton and Bay City, received fair ratings.

Bacteria are the most important determinant of the water quality rating. Sites with bacteria concentrations greater than 399 Most Probable Number/100 milliliters are rated poor. This was the case with the San Saba River and Lake Marble Falls sites. Four Colorado River locations with elevated bacteria concentrations but less than 399 MPN/100 ml fell into the fair category.

Seven sites earned excellent scores:

  • Lakes Buchanan, Inks, LBJ and Travis
  • Llano and Pedernales rivers
  • Colorado River at Columbus

Two sites earned a good score:

  • Colorado River at Bastrop and at Smithville

Four sites earned a fair rating:

  • Colorado River at Austin, La Grange, Wharton and Bay City

Two sites received poor marks:

  • San Saba River near San Saba
  • Lake Marble Falls

Highland Lakes region

The Highland Lakes and major upstream tributaries, the Llano and Pedernales rivers, earned excellent ratings with optimal water quality measurements supportive of healthy aquatic life. The San Saba River and Lake Marble Falls received poor ratings because of elevated bacteria concentrations. The bacteria were likely washed in with rainfall runoff. All monitoring sites in the region reported ideal oxygen levels, and low bacteria and nutrients.

Lakes Buchanan and Travis had transparency to depths of 4.7 and 13.7 feet, respectively. Lake Travis had the greatest transparency of the monitored sites in April. Inks Lake transparency was measured at almost 7 feet. Lakes LBJ and Marble Falls also were transparent to a depth of 4.7 and 4.2 feet, respectively. Transparency in the San Saba River was about 2 1/2 feet. The Pedernales River’s was approximately 3 feet. The Llano River was more transparent and was measured at 4 feet.

Water temperatures in the upper basin ranged from a low of 59 F (15 C) in the San Saba River to 68 F (20 C) in the Llano River. Elsewhere in this geographic area, water temperatures were primarily in the mid 60s.

Downstream

Downstream water quality improved somewhat in April. The nutrient, or nitrate, concentrations at Bastrop and Smithville were still somewhat elevated but less than in March. Further downstream, the nutrient concentrations were higher in April than March. Aquatic plants continue to be very abundant in the river and seem to help filter suspended solids in the water. Bacteria concentrations were somewhat elevated. Healthy dissolved oxygen concentrations supportive of fish communities were measured throughout the lower river. The Colorado River at Columbus earned an excellent score.

Water temperatures in the lower basin ranged from a low of 68 F (20 C) at Austin to 74 F (23.6 C) at Columbus. Water temperatures were typically in the lower 70s at other downstream sites. With a transparency tube reading of 1/2 foot, transparency was lowest at Bay City. In the Colorado River downstream of Austin, the greatest transparency was measured at Wharton with 4 feet. The transparencies downstream of Austin averaged slightly less than 3 feet.


For information on a specific lake or river, see a link below:

Austin

Bastrop

Bay City

Columbus

Inks Lake

La Grange

Lake Buchanan

Lake LBJ

Lake Marble Falls

Lake Travis

Llano River

Pedernales River

San Saba

Smithville

Wharton

 
 

Austin Water Quality Rating
 
  Colorado River at Mud Outdoor Center in Austin 

The Colorado River at Austin earned a fair score. Dissolved oxygen levels supported a healthy fish population. Bacteria results were slightly elevated from last month. Nutrient levels were low. The water temperature was 68 F. Transparency was measured at 3 1/2 feet.

 

Bastrop Water Quality Rating
 
  Colorado River at Bastrop's Lost Pines Nature Trails 

The Colorado River at Bastrop received a good water quality rating due primarily to elevated nutrients which are the result of wastewater dominating the river flow. Bacteria concentrations were relatively low. Dissolved oxygen levels were healthy for aquatic life. The water temperature was 70 F. The river transparency was 3 1/3 feet.

 

Bay City Water Quality Rating
 
 

Colorado River at MCBNC Bay City

The Colorado River at Bay City received a fair water quality score primarily due to elevated bacteria. Dissolved oxygen levels supported healthy fish populations. Nutrients were slightly elevated, but they were not unusual for this location and time of year. The water temperature was 74 F. Transparency was 1/2 foot.

 

Columbus Water Quality Rating
 
  Colorado River at Columbus  

The Colorado River at Columbus earned an excellent water quality score. Dissolved oxygen concentrations supported healthy fish populations. Bacteria was low. Nutrient levels were slightly elevated. The water temperature was 74 F and was the warmest measured in April. Transparency was at stream depth or about 2 feet.

 

Inks Lake Water Quality Rating
 
   Inks Lake at Inks Lake State Park

Inks Lake earned an excellent score with all water quality with optimal results. Dissolved oxygen levels supported healthy aquatic life. Bacteria concentrations were low and nutrient concentrations were low. The water temperature was 65 F. The lake transparency, measured with a Secchi disk, was about 6 3/4 feet.

 

La Grange Water Quality Rating
 
  Colorado River at White Rock Park La Grange 

The Colorado River at La Grange water quality earned a fair rating. Dissolved oxygen concentrations supported healthy fish populations. Bacteria were slightly elevated this month. Nutrients were slightly elevated, but were not unusual for this location and lack of river flow. The water temperature was 69 F. Transparency depth was about 3 1/2 feet.

 

Lake Buchanan Water Quality Rating
 
   Lake Buchanan at Burnet County Park 

Lake Buchanan earned an excellent score with all water quality measurements being optimal. Dissolved oxygen levels supported healthy aquatic life. Bacteria levels were low though nitrate concentrations were slightly elevated. The water temperature was 61 F. Lake transparency was measured to a depth of 4.7 feet. The lake elevation was 991.3 feet above mean sea level (MSL).

 

Lake LBJ Water Quality Rating
 
  Lake LBJ at the Landing Strip

Lake LBJ earned an excellent score with all water quality measurements being optimal. Dissolved oxygen concentrations supported a healthy fish population. Nutrient levels were low. The water temperature was 67 F. Lake transparency was about 4 3/4 feet.

 

Lake Marble Falls Water Quality Rating
 
  Lake Marble Falls at Lakeside Park

Lake Marble Falls received a poor score due to elevated bacteria. The lake bacteria resulted from rainfall runoff. Dissolved oxygen levels supported a healthy fish population. Bacteria levels were low while nitrate concentrations were estimated to be low. The water temperature was 67 F. Lake transparency was approximately 4 1/4 feet.

 

Lake Travis Water Quality Rating
Lake Travis
  Lake Travis at Lago Vista

Lake Travis earned an excellent score with all water quality measurements being optimal. Dissolved oxygen levels supported healthy aquatic life. Bacteria and nutrient levels were low. The water temperature was 63 F. Lake transparency was greater than 13 1/2 feet while the lake level was 631.3 feet above MSL.

 

Llano River Water Quality Rating
 
   Llano River at the Slab

The Llano River earned an excellent score with all water quality measurements being optimal. Dissolved oxygen levels supported a healthy fish population. Bacteria concentrations were low. Nutrient concentrations were also low. The water temperature was 68 F. River transparency was good and the bottom was visible to a depth of 4 feet.

 

Pedernales River Water Quality Rating
 
  Pedernales River at LBJ Park

The Pedernales River earned an excellent score with all optimal water quality measurements. Dissolved oxygen levels supported a healthy fish population. Bacteria and nutrient levels were low. The water temperature was 61 F. The river was clear and the bottom was visible at a depth of about 3 feet.

 

San Saba River Water Quality Rating
 
   San Saba River at Maxwell's Crossing

The San Saba River received a poor score. Bacteria concentrations were elevated and attributable to rainfall runoff. Dissolved oxygen levels supported a healthy fish population. Nutrient concentrations were relatively low. The water temperature at the site was 59 F, which was the coolest measurement of all locations in April. River transparency was clear so that the bottom of the stream, nearly 2 1/2 feet deep, was visible.

 

Smithville Water Quality Rating
 
  Colorado River at Hwy 95 in Smithville 

The Colorado River at Smithville earned a good water quality rating due primarily to elevated nutrients. Dissolved oxygen levels supported healthy fish populations. Bacteria levels were low. Nutrients were elevated, but less than what was measured upstream at Bastrop. The water temperature was 69 F while transparency was 3 1/2 feet.

 

Wharton Water Quality Rating
   
  Colorado River at Riverfront Park in Wharton

The Colorado River at Wharton site received a fair rating due primarily to elevated bacteria and nutrients. Dissolved oxygen levels supported healthy fish populations. The water temperature was 74 F. Transparency was determined to be 4 feet.

SWIMMING

LCRA's monthly water quality report is intended to give the public a snapshot of overall water quality conditions. But conditions can change quickly. High water quality index ratings do not preclude the existence of bacteria that may cause infections. Swimming in a river, lake or pond, rather than a disinfected swimming pool, carries some risk. So the public needs to take precautions at all times, such as avoiding stagnant water and staying out of the water after rains.

READING THE RATINGS

LCRA monitors the quality of the lower Colorado River as part of its responsibility as the river's steward. The monthly water quality report is issued monthly utilizing data collected by LCRA staff and Colorado River Watch Network certified volunteers to characterize the general quality of the river, tributaries and Highland Lakes using ratings of “excellent,” “good,” “fair” and “poor.” The index is based on a list of parameters, including dissolved oxygen, fecal coliform or E.coli bacteria, nutrients (phosphorus and/or nitrogen), temperature and total dissolved solids or conductivity.

Here's a primer on what the ratings mean:

  • Excellent: All water quality parameters measured are within optimal ranges. The water quality supports all designated uses and is esthetically pleasing and suitable for swimming. 
  • Good: Most parameters are within acceptable ranges. Slight elevations in nutrients and/or dissolved oxygen levels just outside the preferred ranges may be present. Water quality supports most designated uses and is esthetically pleasing and suitable for swimming.  
  • Fair: Bacteria levels exceed state standards and/or nutrients are above the range suggested by screening levels. Water quality supports noncontact recreational uses but may not be suitable for swimming. 
  • Poor: This rating, used rarely, may occur if both bacteria and nutrients are at undesirable levels. Contact recreation (such as swimming) is not recommended. To date, major flood events have been the primary reason for poor ratings.
— Updated on April 23, 2013 at 03:11 PM —

 
 
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