Water
 
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State of the river
Water Quality Index
September 2008

The Colorado River basin’s water quality is influenced by widely varying weather. This month most of the region narrowly missed much needed rain as two hurricanes skirted the area. Though late August brought 2-3 inches of rain throughout the watershed, only the coastal region saw any rain during early September. As a result, the river and its tributaries received very little fresh flow, resulting in slightly depressed dissolved oxygen levels throughout the basin.

Upstream of Austin, Lakes Buchanan and Marble Falls and the Pedernales River received water quality ratings of excellent with dissolved oxygen levels within optimal ranges for this time of year. The San Saba and Llano Rivers and lakes LBJ and Travis were rated good. Transparency in the lakes declined slightly from last month but the general trend was one to two feet in the upper Highland Lakes to more than four feet in Lake Travis. Bacteria and nutrients were low throughout the area. The Llano River was the coolest at 77° and the average temperature throughout was 81°.
 
In the lower basin, the area between Columbus and Bay City received only one to two inches of rain from Hurricane Ike, not enough to impact water quality. Dissolved oxygen levels were somewhat higher than upstream. Most water quality ratings were classified as good, with the exception of the Colorado River at Austin’s excellent rating. Nutrients in the Colorado River below Austin were somewhat elevated due to wastewater facility discharges, but bacteria levels were low. Water temperatures were in the upper 70’s to a high of 86° at Bay City.

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

Austin

Bastrop

Bay City

Columbus

La Grange

Lake Buchanan

Lake LBJ

Lake Marble Falls

Lake Travis

Llano River

Pedernales River

San Saba

Smithville

Wharton
 
 

Austin
Rating: Excellent
Water quality parameters for the Colorado River at Austin were within optimal ranges for this time of year, including dissolved oxygen high enough for a healthy fish community. Bacteria and nutrient levels were low and therefore not a concern for contact recreation. The water temperature was 77° F.

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The Colorado River at the 969 bridge at Bastrop.

Bastrop
Rating: Good
Water quality was rated good on the Colorado River at Bastrop. Dissolved oxygen levels were high enough to support a healthy fish community. Nutrient levels were slightly elevated due to wastewater facility discharges. Bacteria levels were low and therefore not a concern for contact recreation. The water temperature was 81° F.

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Bay City
Rating: Good

The Colorado River at Bay City's Riverside Park.
Water quality for the Colorado River at Bay City was rated good with dissolved oxygen levels high enough to support a healthy fishery. Nutrient levels were low. Bacteria levels were also low and therefore not a concern for contact recreation. The water temperature was 86° F.

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Columbus
Rating: Good
The Colorado River at Columbus was rated good. Dissolved oxygen was high enough to support a healthy fishery. Nutrient levels were slightly elevated due to wastewater facility discharges. Bacteria levels were low and therefore not a concern for contact recreation. The water temperature was 82° F.

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La Grange
Rating: Good
The water quality on the Colorado River at La Grange was rated good. Dissolved oxygen was high enough to support a healthy fishery. Though nutrient levels were slightly elevated due to wastewater facility discharges, bacteria levels were not a concern for contact recreation. The water temperature was 77° F.

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Lake Buchanan
Rating: Excellent
Water quality at Lake Buchanan was excellent, with dissolved oxygen levels high enough for a healthy fishery. Bacteria levels were low and not a concern for swimmers. Nutrient levels were low and water clarity was 1 and ½ feet. The water temperature was 82° F.

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Lake LBJ
Rating: Good
Water quality measurements were good at Lake LBJ Dissolved oxygen was slightly lower than last month but still high enough to support a healthy fishery. Bacteria and nutrient levels were low and therefore not a concern for contact recreation. The water temperature was 82° F and water clarity was almost 4 feet again this month.

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Lake Marble Falls
Rating: Excellent
Water quality parameters were within optimal ranges for this time of year, including dissolved oxygen high enough for a healthy fish community. Bacteria and nutrient levels were low and therefore not a concern for contact recreation. The water temperature was 82° F and clarity was 4 feet.

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Lake Travis
Rating: Good
Water quality parameters were within acceptable ranges for this time of the year. Dissolved oxygen was high enough to support a healthy fish community. Nutrients and bacteria levels were low and therefore not a concern for contact recreation. The water temperature was 84° F and water clarity was 4.5 feet.

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Llano River
Rating: Good
Water quality on the Llano was good this month. Dissolved oxygen was high enough to support a healthy fishery. Bacteria and nutrient levels were low and therefore not a concern for contact recreation. The water temperature was 82° F.

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Hammets Crossing on Pedernales River
Hammett's Crossing on the Pedernales River is one of 14 sites monitored each month.

Pedernales River
Rating: Excellent
Water quality was rated excellent as readings were within optimal ranges established for this time of the year. Dissolved oxygen was high enough to support a healthy fishery. Bacteria and nutrient levels were low and therefore not a concern for contact recreation. The water temperature was 82° F.

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San Saba River at Risien Park
Rating: Good
The San Saba River was rated good this month. Dissolved oxygen, though lower than last month, was high enough to support a healthy fish community. Bacteria and nutrient levels were low and therefore not a concern for contact recreation. The water temperature was 77° F.

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Smithville
Rating: Good
Water quality measurements were within expected ranges for this time of the year for the Colorado River at Smithville. Though dissolved oxygen levels were slightly lower than last month, they were still high enough to support a healthy fish community. Nutrient levels were within the norm. Bacteria levels were low and therefore not a concern for contact recreation. The water temperature was 81° F.

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Wharton
Rating: Good
Water quality for the Colorado River at Wharton was rated as good. Dissolved oxygen was high enough to support a healthy fishery. Nutrient levels were slightly elevated due to wastewater facility discharges. Bacteria levels were low and therefore not a concern for contact recreation. The water temperature was 84° F.

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MORE RESOURCES
READING THE RATINGS

The water quality index is issued monthly by LCRA to characterize the general water quality of the rivers, tributaries and Highland Lakes. The index is based on six parameters: dissolved oxygen, nitrogen, phosphorus, temperature, total dissolved solids, and fecal coliform bacteria.

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: At least four of six parameters are within the acceptable ranges. The water quality supports most designated uses and is esthetically pleasing and suitable for swimming.
  • Fair: Half of the parameters are not within acceptable ranges or bacteria levels exceed state standards. Water quality supports noncontact recreational uses but may not be suitable for swimming.
  • Poor: At least four of the six parameters, including fecal bacteria, are outside acceptable limits. Contact recreation (such as swimming) is not recommended. To date, major flood events have been the primary reason for a poor rating.