Research about Conroe, Texas

USGS2025

Spatial and seasonal water-quality patterns and temporal water-quality trends in Lake Conroe on the West Fork San Jacinto River near Conroe, Texas, 1974–2021

The impoundment of Lake Conroe in 1973 created an important water resource for greater Houston, Texas. The U.S. Geological Survey, in cooperation with the San Jacinto River Authority, analyzed water-quality data collected from 1974 to 2021 at upreservoir, mid-reservoir, and downreservoir sites in Lake Conroe. Water-column and seasonal variability of selected water-quality constituents (physiochemical properties, major ions, nutrients, and trace metals) were assessed, as well as thermal stratification. Water-quality trends were evaluated for 1974–2021 and 1993–2021. Near-surface water (1–3 feet below the water surface) was warmer and contained higher dissolved-oxygen concentrations compared to near-bottom water (2–3 feet above the reservoir bottom). Dissolved-oxygen concentrations were lowest in summer and highest in winter. Specific conductance was higher near the bottom and varied seasonally, being lowest in winter and highest in summer. Values of pH were generally higher at the surface, with some variability between sites and seasons. Water transparency was higher downreservoir and seasonally lowest in summer. Major-ion concentrations varied minimally within the water column and seasonally, except for sulfate, which was higher in winter and lower in summer. Most nutrient and trace metal concentrations were highest near the bottom during summer, notably at deeper sites. Thermal stratification in Lake Conroe begins in spring and peaks in summer and was limited to the deeper parts of the reservoir. The seasonal variability observed in dissolved constituent concentrations was driven by thermal stratification. Trend analyses for 1974–2021 indicated positive trends in water temperature, dissolved oxygen, pH, potassium, sodium, and silica. Negative trends were detected for calcium and magnesium near the reservoir bottom. During 1993–2021, positive trends were detected for near-surface dissolved-oxygen concentration, specific conductance, pH, all major ions excluding sulfate, and near-surface ammonia plus organic nitrogen concentration. Negative trends were determined for ammonia, iron, and manganese concentrations. Water transparency generally decreased over time.

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USGS2010

Streamflow and water-quality properties in the West Fork San Jacinto River Basin and regression models to estimate real-time suspended-sediment and total suspended-solids concentrations and loads in the West Fork San Jacinto River in the vicinity of Conroe, Texas, July 2008-August 2009

To better understand the hydrology (streamflow and water quality) of the West Fork San Jacinto River Basin downstream from Lake Conroe near Conroe, Texas, including spatial and temporal variation in suspended-sediment (SS) and total suspended-solids (TSS) concentrations and loads, the U.S. Geological Survey, in cooperation with the Houston-Galveston Area Council and the Texas Commission on Environmental Quality, measured streamflow and collected continuous and discrete water-quality data during July 2008-August 2009 in the West Fork San Jacinto River Basin downstream from Lake Conroe. During July 2008-August 2009, discrete samples were collected and streamflow measurements were made over the range of flow conditions at two streamflow-gaging stations on the West Fork San Jacinto River: West Fork San Jacinto River below Lake Conroe near Conroe, Texas (station 08067650) and West Fork San Jacinto River near Conroe, Texas (station 08068000). In addition to samples collected at these two main monitoring sites, discrete sediment samples were also collected at five additional monitoring sites to help characterize water quality in the West Fork San Jacinto River Basin. Discrete samples were collected semimonthly, regardless of flow conditions, and during periods of high flow resulting from storms or releases from Lake Conroe. Because the period of data collection was relatively short (14 months) and low flow was prevalent during much of the study, relatively few samples collected were representative of the middle and upper ranges of historical daily mean streamflows. The largest streamflows tended to occur in response to large rainfall events and generally were associated with the largest SS and TSS concentrations. The maximum SS and TSS concentrations at station 08067650 (180 and 133 milligrams per liter [mg/L], respectively) were on April 19, 2009, when the instantaneous streamflow was the third largest associated with a discrete sample at the station. SS concentrations were 25 mg/L or less in 26 of 29 environmental samples and TSS concentrations were 25 mg/L or less in 25 of 28 environmental samples. Median SS and TSS concentrations were 7.0 and 7.6 mg/L, respectively. At station 08068000, the maximum SS concentration (1,270 mg/L) was on April 19, 2009, and the maximum TSS concentration (268 mg/L) was on September 18, 2008. SS concentrations were 25 mg/L or less in 16 of 27 of environmental samples and TSS concentrations were 25 mg/L or less in 18 of 26 environmental samples at the station. Median SS and TSS concentrations were 18.0 and 14.0 mg/L, respectively. The maximum SS and TSS concentrations for all five additional monitoring sites were 3,110 and 390 mg/L, respectively, and the minimum SS and TSS concentrations were 5.0 and 1.0 mg/L, respectively. Median concentrations ranged from 14.0 to 54.0 mg/L for SS and from 11.0 to 14.0 mg/L for TSS. Continuous measurements of streamflow and selected water-quality properties at stations 08067650 and 08068000 were evaluated as possible variables in regression equations developed to estimate SS and TSS concentrations and loads. Surrogate regression equations were developed to estimate SS and TSS loads by using real-time turbidity and streamflow data; turbidity and streamflow resulted in the best regression models for estimating near real-time SS and TSS concentrations for stations 08097650 and 08068000. Relatively large errors are associated with the regression-computed SS and TSS concentrations; the 90-percent prediction intervals for SS and TSS concentrations were (+/-)48.9 and (+/-)43.2 percent, respectively, for station 08067650 and (+/-)47.7 and (+/-)43.2 percent, respectively, for station 08068000. Regression-computed SS and TSS concentrations were corrected for bias before being used to compute SS and TSS loads. The total estimated SS and TSS loads during July 2008-August 2009 were about 3,540 and 1,900 tons, respectively, at station 08067650 and about 156,000 an

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