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Lake Conroe Clean Rivers Sampling Program:

Lake Conroe Clean Rivers Sampling Program:

Earning A 5-star (er, Frog) Rating

Lake Conroe was constructed in the late 1960s to the early 1970s in a joint venture between the San Jacinto River Authority (SJRA) and City of Houston with the sole purpose of providing a drinking water source to serve future demand in the greater Houston Metropolitan area.  

As a partner in the project, SJRA takes great pride in operating and maintaining the Lake Conroe Dam and Reservoir.  Included in the responsibilities is the charge of assessing the quality of the water in the reservoir.  In cooperation with the Houston Galveston Area Council (HGAC), SJRA administers the Clean Rivers Program (CRP) on Lake Conroe.  The CRP is a water quality initiative overseen by Texas Commission on Environmental Quality (TCEQ) for the purpose of monitoring the overall health of Texas Waterways.  

Continuous monitoring of the quality of water in Lake Conroe is important not only because of its function as a regional drinking water source, but also due to its popularity as a recreational destination for boating, fishing, and a variety of other water sports and hobbies.   The TCEQ requires water bodies to meet established water quality standards based on their “use.”  The official “uses” of Lake Conroe, as designated by TCEQ, are drinking water supply, recreation, and fish consumption.  Therefore Lake Conroe is held to the most stringent water quality standards set forth by TCEQ. 

There are currently ten monitoring sites in the Lake Conroe CRP Program (Figure 1).  These sites are all located in the main body of the lake and were chosen to capture water quality parameters from all of the major contributing tributaries.  At each designated site, SJRA samples for 11 different water quality parameters (See Table 1).  Some specimens are collected, preserved, and delivered to an outside lab for detailed analysis.  

Other samples are considered field parameters and are collected instantaneously with a water quality measuring device called a sonde (See Figure 3).  The sonde is deployed over the side of a boat to different depths in the water column.  At each defined depth, four water quality parameters are measured: pH, specific conductivity, temperature, and dissolved oxygen.  Data collected with the sonde can be downloaded to a personal computer and charted in order to detect changes in water quality throughout the water column for each month of the year.  This information is useful to Texas Parks and Wildlife fisheries biologists as well as water treatment facility operators.  

Another sampling device is known as a secchi disk and is used to measure the turbidity—or level of clarity– of water (See Figure 4).  The secchi disk is lowered into the water until it is no longer visible, at which point a depth measurement is taken and recorded.  The greater the depth that the secchi disk remains visible, the less turbid the water.  These extensive sampling procedures allow SJRA to establish a complete picture of the water quality in Lake Conroe.

Data gathered from each sampling site is then compared to TCEQ water quality standards and screening levels.  If a parameter exceeds the standard or screening level for a continued period of time, the lake will be deemed impaired by TCEQ.  To date, Lake Conroe has never been determined to be impaired and, in fact, remains one of the cleanest water bodies in the region.  Each year HGAC issues a Basin Highlights/ Summary Report, which ranks all water bodies in the region based on overall water quality.  The rankings range from poor water quality, identified as a one frog rating, to excellent water quality, receiving a five frog rating (See Figure 2).  SJRA is proud that Lake Conroe is considered a 5-frog reservoir (See Figure 1). 

Lake Conroe has excellent water quality and SJRA works diligently to protect this great resource for the public.  It will take SJRA and the public working together to keep water quality at such a high level. If you have any questions about the water quality program on Lake Conroe, please contact Shane Simpson at [email protected]

Precautions Regarding COVID-19 (Lake Conroe open to families at this time)

Lake Conroe continues to stay open and can provide a welcome change to staying indoors.  If visiting Lake Conroe, please continue to observe federal, state, and local COVID-19 guidelines including:

  • Follow CDC recommendations on social distancing.
  • Limit gatherings of people to a family unit.
  • Follow recommended hygiene practices including frequent hand washing when visiting any common spaces such as marinas, gas stations, or boat launches.

“Our highest priority is for the health and well-being of Lake Conroe visitors and businesses,” said SJRA General Manager Jace Houston.  “We want people to get outside with their families and enjoy the lake.  We just need people to do it in a way that keeps them safe and healthy.”

“Precinct 1 advises everyone to enjoy Lake Conroe but make sure that you are following best practices and social distancing while on the water,” said Lt. Cade Montgomery County Precinct 1 Constable’s Office.  “Make sure to keep your party to family units only, wash your hands, and for more information regarding COVID-19 visit www.mctx.org.”

One of the major river authorities in Texas, SJRA’s mission is to develop, conserve, and protect the water resources of the San Jacinto River basin.  Covering all or part of seven counties, the organization’s jurisdiction includes the entire San Jacinto River watershed, excluding Harris County.  For additional information on SJRA visit our website at www.sjra.net, like SJRA on Facebook @SanJacintoRiverAuthority, follow us on Twitter @SJRA_1937, or find us on Instagram @SanJacintoRiverAuthoritySJRA.

Fig 1. CRP Lake Conroe Sampling Locations

Fig 2: HGAC 2019 Regional Water Quality Summary Frog Chart

Parameters TCEQ Screening Levels/ Standards Limits
Alkalinity N/A
Chloride >50 mg/L
E Coli MPN/ 100mL
Ammonia 0.11 mg/L
Nitrate >.37 mg/L
Sechhi Depth N/A
Sulfate >50 mg/L
Total Phosphorus >.20 mg/L
Total Suspended Solids N/A
Chlorophyll >26.7 ppb
Total Kjeldahl Nitrogen N/A
Dissolved Oxygen <3.0 mg/L
Specific Conductivity N/A
Temperature > 32.22 *C
pH N/A

Table 1: Parameters and TCEQ Screening Levels/ Standards Limits for CRP Lake Conroe

MS5: Hydrolab MiniSonde® 5 Multiprobe SE

Fig. 3: MS5 Hydrolab Water Quality Sonde

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