Water Resources of Calcasieu Parish, Louisiana

Knowing how much water Calcasieu Parish, Louisiana, has, how it is used and how good it is matters for managing it. This U.S. Geological Survey fact sheet, by Vincent E. White and Lawrence B. Prakken and prepared with the Louisiana Department of Transportation and Development, draws on earlier reports and the USGS National Water Information System to give water managers, residents and others that picture.

How much water is used

In 2010 the parish withdrew about 223.7 million gallons a day (Mgal/d): 136.7 from surface water and 87.0 from groundwater. Industry took the majority, 156.5 Mgal/d; the rest went to public supply, power generation, rural homes, livestock, rice and general irrigation, and aquaculture. Records kept every five years since 1960 show withdrawals peaking in 1970 at about 1,020 Mgal/d; the long decline since is largely due to less water used by industry and for rice.

Groundwater and surface-water withdrawals in Calcasieu Parish, 1960–2010. USGS.

Groundwater

Fresh groundwater — no more than 250 milligrams per litre (mg/L) of chloride — occurs in several aquifers, to different depths in different places. Its base lies from about 400 to almost 2,500 feet below the National Geodetic Vertical Datum of 1929 (NGVD 29). The deepest fresh water is north of DeQuincy, in the Williamson Creek aquifer; elsewhere in roughly the northern quarter of the parish, the base is about 700 to 2,000 feet or more down, in the Evangeline aquifer; in the southern three-fourths it is about 500 to 800 feet down, in the Chicot aquifer system.

Calcasieu Parish: depth to the base of fresh groundwater, subbasins, and the wells and river sites described here. USGS.

The Chicot aquifer system

The Chicot is an important regional aquifer system under most of southwestern Louisiana. It reaches the surface and is recharged in parishes to the north and northeast, where it is largely a single thick sand. That sand thickens and deepens southward and, near the parish's northern border, is split by clay layers into a complex series of sands. West of roughly the longitude of Iowa, these are the "200-foot," "500-foot" and "700-foot" sands of the Lake Charles area; east of it, the Chicot upper and lower sands, connected to the "200-foot" and "700-foot" sands. A surface layer of clay, from 40 feet thick in small areas of the northwest and northeast to 280 feet in the south-centre, limits how much rain soaks in; scattered sand streaks and lenses within it make up the "shallow sand unit."

The three main sands are alike but lie at different depths:

• "200-foot" sand: fine to medium sand at the top grading to coarse sand or gravel at the base; its top is 0–50 feet above NGVD 29 near the northeast corner and more than 300 feet below in the southwest corner.
• "500-foot" sand: fine sand at the top grading to coarse sand and gravel near the base; its top is less than 400 feet below NGVD 29 in the north and more than 600 feet below in the southeast corner, and its base from more than 400 to more than 800 feet below.
• "700-foot" sand: tan to greyish, fine at the top and coarse at the base; its top is less than 400 feet down in the north and more than 800 feet in the southeast corner, and the base of the lower sand and "700-foot" sand from more than 400 feet in the north to more than 1,000 feet in the southeast corner.

In 2015 more than 4,900 active wells were screened in the Chicot system, most in these three sands, at depths of 13 to 849 feet, with yields up to 5,471 gallons a minute. In 2010 the "500-foot" sand supplied the most, 70.97 Mgal/d.

Water levels in all three sands behave alike. In 2011–12 they ranged from highs of about 7.6 feet above, 2.4 feet below and 14.1 feet below NGVD 29 (in the "200-," "500-" and "700-foot" sands) to lows of 49.9, 79.6 and 69.6 feet below. They are lowest near the Calcasieu River in the Lake Charles area, matching the known movement of groundwater toward it, and have generally risen by as much as 20 feet since the 1970s because of reduced pumping.

Groundwater quality

Samples from 111 wells in the "200-foot" sand, 239 in the "500-foot" sand and 63 in the "700-foot" sand had median hardness in the moderately hard range. More than 90 percent of samples from each were within the Environmental Protection Agency's secondary (non-enforceable) limit for pH, and more than 80 percent within its limit for dissolved solids. Median iron was below the limit in the "200-foot" sand but far above it in the "500-foot" and "700-foot" sands.

Saltwater — more than 250 mg/L of chloride — occurs both locally and widely in the Chicot system here:

• at the base of the "200-foot" sand and in the upper sand: along most of the southern boundary, in the southeast corner and near Iowa;
• at the base of the "500-foot" sand: along much of the southern boundary, in the southeast corner and in three small areas at or near industrial plants between Lake Charles and Sulphur;
• at the base of the "700-foot" sand and in the lower sand: across the southern two-thirds of the parish; along most of the southern boundary the "700-foot" sand holds only saltwater.

Surface water

The parish lies in two basins: the Calcasieu–Mermentau, covering most of it, and the Sabine, along the Sabine River in the west. In 2010 about 136.7 Mgal/d of surface water was withdrawn, more than 95 percent of it from the Calcasieu River (76.22 Mgal/d) and the Sabine River Diversion System (54.07 Mgal/d).

• West Fork Calcasieu and Upper Calcasieu subbasins, across most of the northern half, drain south into the Lower Calcasieu subbasin and on to the Gulf of Mexico. The Houston River and Indian Bayou feed the West Fork Calcasieu River, which joins the Calcasieu just upstream of Lake Charles; Bayou Serpent and many small streams feed the Calcasieu. Upstream near Kinder, the Calcasieu averaged 2,524 cubic feet per second in 1922–2014, from 1,700 square miles.
• Lower Calcasieu subbasin: the Calcasieu River, Bayou Choupique, the Gulf Intracoastal Waterway and many small streams, with several lakes along the river.
• Mermentau subbasin, in the southeast corner, drained by Bayou Lacassine.
• Lower Sabine subbasin: the Sabine River drains a strip along the western border and is linked to the interior by canals. The Sabine River Diversion System carries Sabine water east by canal to industries near Westlake and Sulphur and supplies towns and irrigation. Near Ruliff, Texas, the Sabine averaged 7,626 cubic feet per second in 1961–2015, from about 9,330 square miles. The Gulf Intracoastal Waterway crosses the south of the parish from the Texas line, over the Calcasieu River just south of Moss Lake, into Cameron Parish.

Surface-water quality

Samples from the Calcasieu River near Lake Charles (1968–78) and the Sabine River near Ruliff (1967–2000) had median hardness in the soft range; more than 80 percent were within the iron limit and median pH was within limits. Dissolved oxygen was generally above 5 mg/L, considered the minimum for a diverse community of warm-water life, including sport fish.

Sources

• Vincent E. White and Lawrence B. Prakken, Water Resources of Calcasieu Parish, Louisiana, USGS Fact Sheet 2016–3066, January 2017, in cooperation with the Louisiana Department of Transportation and Development. https://doi.org/10.3133/fs20163066
• USGS Lower Mississippi-Gulf Water Science Center: http://la.water.usgs.gov