Water Resources of Sabine Parish, Louisiana

How much water Sabine Parish, Louisiana, has, how it is used and how good it is — from a U.S. Geological Survey fact sheet prepared with the Louisiana Department of Transportation and Development, drawing on earlier reports and the USGS National Water Information System.

How the water is used

In 2010 the parish withdrew about 3.85 million gallons a day (Mgal/d): 2.09 Mgal/d of groundwater and 1.76 Mgal/d of surface water.

By source: the Carrizo-Wilcox aquifer 1.81 Mgal/d, the Sparta 0.13, the Cockfield 0.07, the Catahoula 0.05 and the Upland terrace aquifer 0.03; Toledo Bend Reservoir 1.35 and other water bodies 0.41. Counted every five years since 1960, withdrawals peaked in 1990.

Groundwater

The main sources of fresh groundwater — chloride of 250 milligrams per litre (mg/L) or less — are the Cockfield, Sparta and Carrizo-Wilcox aquifers. The Upland terrace and Catahoula aquifers and the Jasper aquifer system are also present but of limited extent. Fresh groundwater is available throughout the parish; its base lies from more than 100 feet above the National Geodetic Vertical Datum of 1929 (NGVD 29) near the Sabine River in the west-centre to about 1,800 feet below it in the southeast corner.

Rain recharges the aquifers where they reach the surface, in the parish and to the north. They drain naturally into streams in season, leak into neighbouring aquifers, and are pumped. In 2010 state records listed 1,389 active wells — 1,186 domestic, 122 irrigation, 64 public supply and 17 industrial.

Cockfield aquifer

Sands and clays between the Vicksburg-Jackson confining unit above and the Cook Mountain confining unit below. It outcrops in a band about 3 to 5 miles wide running southwest to northeast through Florien and Mount Carmel; its top lies about 1,000 feet below NGVD 29 in the southeast corner and about 1,500 feet in the southwest. In 1993 its water flowed generally east or southeast in the southeast of the parish but southwest in the southwest. At well Sa-392, screened 544 feet down, levels usually vary 1 foot or less a year.

• 129 active wells in 2010 (111 domestic, 8 public supply, 6 irrigation, 4 industrial), 15 to 2,112 feet deep (median 164), yielding 3 to 300 gallons per minute.
• Withdrawals in 2010: about 0.07 Mgal/d, all rural domestic.
• Samples from 16 wells: median hardness in the soft range; median pH, chloride, manganese and dissolved solids generally within the EPA's secondary maximum contaminant levels (SMCLs).

Sparta aquifer

Outcrops in a band 1 to 2 miles wide, 1 to 2 miles north of the Cockfield outcrop, between the Cook Mountain confining unit above and the Cane River confining unit below. It thickens from about 200 feet near the outcrop to 440 feet near the southeastern boundary, and its regional dip takes it to about 1,800 feet below NGVD 29 near the southern boundary and 2,300 feet near the southeastern. More than 3 to 4 miles south of the outcrop it holds salt water.

• 170 active wells (137 domestic, 18 irrigation, 8 public supply, 7 industrial), 22 to 1,605 feet deep (median 148), yielding 3 to 453 gallons per minute.
• Withdrawals in 2010: about 0.13 Mgal/d — 0.03 public supply, 0.09 rural domestic, and less than 0.01 for irrigation and industry.
• Samples from 19 wells: median hardness soft; median pH, chloride, manganese and dissolved solids within the SMCLs.

Carrizo-Wilcox aquifer

The sands and gravels of the Carrizo and Wilcox aquifers, hydraulically connected and treated as one. It outcrops across the northern two-thirds of the parish above the Midway confining unit; in the southern third it dips more steeply under the Cane River confining unit. Present under most of the parish, it is the principal source of fresh groundwater.

Alternating sand, silt and clay beds thicken from about 500 feet in the north to 3,500 feet in the southeast corner. Individual very fine to medium sand beds run from less than 5 to about 250 feet thick (about 30 on average), separated by clays from under 1 to over 100 feet thick. Salt water appears in the Wilcox at depths from 200 feet above NGVD 29 in places to more than 800 feet below; south of a line roughly between Esto and Fisher the Wilcox holds only salt water.

In 1991 water levels ranged from about 220 feet above NGVD 29 in the north-centre, near the De Soto Parish line, to less than 160 feet in the southwest, and water flowed mostly south. Levels follow rainfall; at well Sa-465, screened 80 feet down, they varied up to about 6 feet a year.

• 822 active wells (699 domestic, 75 irrigation, 42 public supply, 6 industrial), 11 to 2,000 feet deep (median 188), yielding 3 to 360 gallons per minute.
• Withdrawals in 2010: about 1.81 Mgal/d — 1.23 public supply, 0.12 industrial, 0.45 rural domestic and 0.01 livestock.
• Samples from 70 wells: median hardness soft; median pH, chloride, iron and manganese within the SMCLs.

Surface water

About 1.76 Mgal/d of surface water was withdrawn in 2010; public supply took about 74 percent (1.30 Mgal/d), the rest going to industry and livestock. Toledo Bend Reservoir on the Sabine River supplied about 77 percent (1.35 Mgal/d). Major streams include Bayou San Patricio, Bayou San Miguel, Bayou Scie, Bayou La Nana and Bayou Toro.

Toledo Bend Reservoir was built mainly for water supply, hydroelectric power and recreation, and completed in 1969. At full pool it normally covers about 185,000 acres. At its conservation stage of 172 feet above NGVD 29 it stores 4,472,900 acre-feet (an acre-foot is enough to cover an acre a foot deep, about 325,851 gallons); mean annual runoff for 1972–2012 was 4,017,000 acre-feet. It reaches about 65 miles up the Sabine to just north of Logansport. Before it, the Sabine at Logansport averaged 3,325 cubic feet per second (1904–60); by 1961 the drainage area was heavily regulated, and flow averaged 2,252 cubic feet per second in 1961–67.

• Sabine River at Logansport (1971–85): generally soft to moderately hard; chloride and sulfate within the SMCLs; iron within it in 89 percent of samples; dissolved oxygen generally above 5 mg/L, the minimum for a varied community of warm-water life, sport fish included.
• Bayou San Patricio near Benson — which enters the parish about 4 miles north-northeast of Converse, east of the reservoir (1955–88): chloride and sulfate within the SMCLs, but iron generally above its SMCL; dissolved oxygen generally above 5 mg/L.

Sources

• Prakken, L.B., White, V.E., and Lovelace, J.K., 2014, Water resources of Sabine Parish, Louisiana: U.S. Geological Survey Fact Sheet 2014–3040, prepared in cooperation with the Louisiana Department of Transportation and Development. https://pubs.usgs.gov/publication/fs20143040
• The tables and figures come from the fact sheet's PDF, which the web version lacks.
• Rewritten in hubnx's own words.