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| Texas Water Science Center |
By Debra A. Sneck-Fahrer, Matthew S. Milburn, Jeffery W. East, and Jeannette H. Oden
U.S. Geological Survey
Scientific Investigations Report 2005–5241
In cooperation with the City of Houston
Lake Houston is a major source of public water supply and recreational resource for the Houston metropolitan area, Texas. Water-quality issues of potential concern for the lake have included nutrient enrichment (orthophosphorus, total phosphorus, nitrite plus nitrate) and aquatic life use (dissolved oxygen). The U.S. Geological Survey, in cooperation with the City of Houston, collected water samples from three sites in Lake Houston and from two streams that discharge to the lake during 2000–2004. Nitrogen compounds, phosphorus, suspended sediment, organic carbon, turbidity, chlorophyll-a, and selected pesticide compounds in water were assessed for all sites. Water-quality conditions of the lake and inflow streams were assessed, and loads and yields were computed for selected constituents in the streams. Selected constituents from samples collected in Lake Houston during 1990–2004 were tested for trends. The three sites sampled in Lake Houston characterized water available to the City of Houston pumping station (site AC), water entering the lake from the largely rural eastern subbasin (site EC), and water entering the lake from the more urbanized, western subbasin (site FC). Most constituent concentrations were largest at site FC, smallest at site EC, and intermediate at site AC. Organic nitrogen was the dominant form of nitrogen in samples collected at all sites. Nitrite plus nitrate concentrations were largest at site FC. Total phosphorus concentrations in all samples were larger than that recommended by the U.S. Environmental Protection Agency to limit aquatic growth in reservoirs. There was a wide range in suspended-sediment concentrations and turbidity in the lake. Twelve pesticides were detected. Atrazine and its breakdown product, 2-chloro-4-isopropylamino-6-amino-s-triazine (CIAT), were the most commonly detected pesticides; concentrations of atrazine were larger than the U.S. Environmental Protection Agency maximum contaminant level of 3.0 micrograms per liter in two samples at site FC. The relative contributions to the water quality of Lake Houston from the eastern and western subbasins were examined by collecting water samples in Cypress Creek and East Fork San Jacinto River. Nitrate and pesticide concentrations were larger in Cypress Creek than in East Fork San Jacinto River. In Cypress Creek, nitrate was the primary form of nitrogen at low flows. Atrazine exceeded 3.0 micrograms per liter in three of 17 samples, with the maximum measured concentration of 21.3 micrograms per liter. In East Fork San Jacinto River, organic nitrogen was the primary form of nitrogen. Atrazine was detected in six of 15 samples. The maximum atrazine concentration was 0.233 microgram per liter. Constituent yields allowed direct comparison of loads from Cypress Creek and East Fork San Jacinto River. In Cypress Creek, storm yields of nitrite plus nitrate nitrogen for high flows ranged from 8 to 45 pounds per square mile per day; in East Fork San Jacinto River, the maximum storm yield for high flows was 1.47 pounds per square mile per day. At low flows, the median daily yield of dissolved phosphorus from Cypress Creek was 84 times larger than the median daily yield from East Fork San Jacinto River; at high flows, it was 16 times larger. At high flows, the maximum daily yield of atrazine from Cypress Creek was 460 times larger than the maximum daily yield at high flows from East Fork San Jacinto River. The concentrations of most constituents at Lake Houston sites showed no trend during 1990–2004; however, significant trends overall or for particular seasons, or both, were detected at some sites for nitrite plus nitrate, dissolved phosphorus, dissolved organic carbon, chlorophyll-a, and diazinon (2000–2004 data only for diazinon).
Abstract
Introduction
Purpose and Scope
Description of the Study Area
Sources and Implications of Nitrogen, Phosphorus, Suspended Sediment, Organic Carbon, Turbidity, Chlorophyll-a, and Pesticides
Acknowledgments
Methods of Study
Data Collection and Analysis
Quality Assurance and Quality Control
Load and Yield Computations
Trend Testing
Water-Quality Assessment of Lake Houston
Ambient Conditions, 2000–2004
Nitrogen
Phosphorus, Suspended Sediment, and Organic Carbon
Transparency, Turbidity, and Chlorophyll-a
Pesticides
Tributary Inflows, 2000–2004
Constituent Concentrations
Loads and Yields
Water-Quality Trends, 1990–2004
Implications
Summary
References
Appendixes
| 1. | Statistical Summary of Field Measurements and Physical Properties, Major Cations and Anions, Nutrients, Biological Constituents, Trace Elements, and Pesticides at Lake Houston, Site AC, February 2000–September 2004 |
| 2. | Statistical Summary of Field Measurements and Physical Properties, Major Cations and Anions, Nutrients, Biological Constituents, Trace Elements, and Pesticides at Lake Houston, Site EC, February 2000–September 2004 |
| 3. | Statistical Summary of Field Measurements and Physical Properties, Major Cations and Anions, Nutrients, Biological Constituents, Trace Elements, and Pesticides at Lake Houston, Site FC, February 2000–September 2004 |
| 4. | Statistical Summary of Field Measurements and Physical Properties, Major Cations and Anions, Nutrients, Biological Constituents, Trace Elements, and Pesticides in Samples Collected From Low Flows at Cypress Creek, June 2000–September 2004 |
| 5. | Statistical Summary of Field Measurements and Physical Properties, Major Cations and Anions, Nutrients, Biological Constituents, Trace Elements, and Pesticides in Samples Collected From High Flows at Cypress Creek, April 2002–November 2004 |
| 6. | Statistical Summary of Field Measurements and Physical Properties, Major Cations and Anions, Nutrients, Biological Constituents, Trace Elements, and Pesticides in Samples Collected From Low Flows at East Fork San Jacinto River, June 2000–September 2004 |
| 7. | Statistical Summary of Field Measurements and Physical Properties, Major Cations and Anions, Nutrients, Biological Constituents, Trace Elements, and Pesticides in Samples Collected From High Flows at East Fork San Jacinto River, April 2002–November 2004 |
| 1–3. | Maps showing: | |
| 1. | Lake Houston drainage basin (study area) near Houston, Texas | |
| 2. | Land-cover distribution in the Lake Houston drainage basin near Houston, Texas, 2002 | |
| 3. | Data-collection sites at Lake Houston, Cypress Creek, and East Fork San Jacinto River near Houston, Texas, 2000–2004 | |
| 4. | Graphs showing (a) total nitrogen and (b) relative contributions to total nitrogen of nitrite plus nitrate nitrogen and ammonia plus organic nitrogen at three sites in Lake Houston near Houston, Texas, February 2000–September 2004 | |
| 5. | Boxplots showing distribution of (a) total nitrogen, (b) nitrite plus nitrate nitrogen, and(c) ammonia plus organic nitrogen at three sites in Lake Houston near Houston, Texas, February 2000–September 2004 | |
| 6. | Graph showing median concentrations of orthophosphate phosphorus, dissolved phosphorus, and total phosphorus at three sites in Lake Houston near Houston, Texas, February 2000–September 2004 | |
| 7–9. | Boxplots showing distribution of: | |
| 7. | (a) Dissolved phosphorus, (b) suspended sediment, and (c) dissolved organic carbon at three sites in Lake Houston near Houston, Texas, February 2000–September 2004 | |
| 8. | (a) Transparency, (b) turbidity, and (c) chlorophyll-a at three sites in Lake Houston near Houston, Texas, February 2000–September 2004 | |
| 9. | (a) Atrazine, (b) 2-chloro-4-isopropylamino-6-amino-s-triazine (CIAT), (c) diazinon, and (d) simazine at three sites in Lake Houston near Houston, Texas, February 2000–September 2004 | |
| 10. | Hydrographs showing discharge, 2000–2004, and water-quality sampling during low flows (June 2000–September 2004) and high flows (April 2002–November 2004) at (a) Cypress Creek and (b) East Fork San Jacinto River near Houston, Texas | |
| 11–14. | Boxplots showing distribution of: | |
| 11. | Nitrogen compounds at low flows (June 2000–September 2004) and high flows (April 2002–November 2004) at (a) Cypress Creek and (b) East Fork San Jacinto River near Houston, Texas | |
| 12. | Orthophosphate phosphorus, dissolved phosphorus, and total phosphorus at low flows (June 2000–September 2004) and high flows (April 2002–November 2004) at (a) Cypress Creek and (b) East Fork San Jacinto River near Houston, Texas | |
| 13. | Suspended sediment at low flows (June 2000–September 2004) and high flows (April 2002–November 2004) at (a) Cypress Creek and (b) East Fork San Jacinto River near Houston, Texas | |
| 14. | Organic carbon at low flows (June 2000–September 2004) and high flows (April 2002–November 2004) at (a) Cypress Creek and (b) East Fork San Jacinto River near Houston, Texas | |
| 1. | Subbasin characteristics for Lake Houston near Houston, Texas |
| 2. | Data-collection sites at Lake Houston, Cypress Creek, and East Fork San Jacinto River, near Houston, Texas, 2000–2004 |
| 3. | Summary of statistical tests used to indicate water-quality trends at Lake Houston, near Houston, Texas, 1990–2004 |
| 4. | Statistical summary of nitrogen compounds, phosphorus, suspended sediment, organic carbon, chlorophyll-a, and selected pesticides for sites AC, EC, and FC combined, Lake Houston near Houston, Texas, February 2000–September 2004 |
| 5. | Summary of pesticide detections at sampling sites in Lake Houston, Cypress Creek, and East Fork San Jacinto River, near Houston, Texas, 2000–2004 |
| 6. | Summary of minimum, median, and maximum loads of selected constituents at low flows and high flows in Cypress Creek near Houston, Texas, 2000–2004 |
| 7. | Summary of minimum, median, and maximum loads of selected constituents at low flows and high flows in East Fork San Jacinto River near Houston, Texas, 2000–2004 |
| 8. | Summary of minimum, median, and maximum yields of selected constituents at low flows and high flows in Cypress Creek near Houston, Texas, 2000–2004 |
| 9. | Summary of minimum, median, and maximum yields of selected constituents at low flows and high flows in East Fork San Jacinto River near Houston, Texas, 2000–2004 |
| 10. | Summary of statistical tests for trends in nitrite plus nitrate, dissolved phosphorus, dissolved organic carbon, chlorophyll-a, and diazinon at three sites in Lake Houston near Houston, Texas, 1990–2004 |
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