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Washington Parish, its rivers and subbasins, and the approximate base of fresh groundwater. USGS.
Knowing how much water Washington Parish, Louisiana, has, how it's used and how good it is matters for managing it well. This USGS fact sheet gathers that information for water managers and residents, from earlier reports and the USGS National Water Information System.
Water use
In 2010 the parish withdrew about 34.55 million gallons per day (Mgal/d): 28.10 from groundwater and 6.44 from surface water. Industry used about 52 percent (17.80 Mgal/d). Withdrawals, recorded every 5 years since 1960, peaked in 1975 at about 51.9 Mgal/d.
| Use, 2010 (Mgal/d) | Groundwater | Surface water | Total |
|---|---|---|---|
| Public supply | 14.26 | 0.00 | 14.26 |
| Industrial | 11.50 | 6.30 | 17.80 |
| Rural domestic | 1.36 | 0.00 | 1.36 |
| Irrigation | 0.85 | 0.00 | 0.85 |
| Livestock | 0.14 | 0.14 | 0.28 |
| Total | 28.10 | 6.44 | 34.55 |
| Source, 2010 (Mgal/d) | Withdrawal |
|---|---|
| Chicot equivalent aquifer system | 6.02 |
| Evangeline equivalent aquifer system | 0.18 |
| Jasper equivalent aquifer system | 21.91 |
| Bogue Lusa Creek | 6.30 |
| Other streams | 0.14 |
Water withdrawals, 1960–2010. USGS.
Groundwater
Fresh groundwater (chloride 250 mg/L or less) comes from the regional Chicot, Evangeline and Jasper equivalent aquifer systems; deeper aquifers hold saltwater. The base of fresh water is deepest along the parish's southern line and shallowest in the north. The aquifers are recharged mainly by rain soaking in across an area stretching from the parish to about 85 miles north of the Louisiana–Mississippi line, and discharge through wells, flow between aquifers, and seepage into streams.
A generalized west-to-east section through the parish's aquifers (vertical scale exaggerated). USGS.
| Chicot (Upland terrace aquifer) | Evangeline | Jasper | |
|---|---|---|---|
| Aquifers | Upland terrace only | Lower Ponchatoula, Big Branch, Kentwood, Abita, Covington | Tchefuncta, Hammond, Amite, Ramsay, Franklinton |
| Material | fine sand to pea gravel | sand to very coarse sand, separated by clay | fine to coarse sand, mostly fresh |
| Base | ~100 ft above NGVD 29 (north) to >300 ft below (southeast) | <300 ft below (north) to >900 ft below (south) | <2,300 ft below (north) to >3,000 ft below (south) |
| Active wells, 2015 | 2,695 (2,472 domestic, 136 irrigation, 79 public supply, 8 industrial) | 108 (84 domestic, 12 irrigation, 7 public supply, 4 industrial, 1 power) | 38 (23 public supply, 7 domestic, 8 industrial) |
| Well depths | 20–470 ft | 150–1,047 ft | 750–2,752 ft |
| Yields | 8–2,000 gal/min | ~1–1,650 gal/min | ~20–2,900 gal/min |
| Withdrawals, 2010 | 6.02 Mgal/d (mostly industrial 3.80, rural domestic 1.30, irrigation 0.85) | 0.18 Mgal/d | 21.91 Mgal/d (public supply 14.20, industrial 7.70) |
- Chicot: the Upland terrace aquifer is broad and shallow, cropping out along ridges and valleys; it dips south, becoming the upper Ponchatoula aquifer in St. Tammany Parish, and correlates with the Citronelle Formation in Mississippi. It is about 100 to over 250 ft thick. In 2009 its water levels ran from about 25 ft above NGVD 29 in the southeast to over 250 ft in the north-central and northwest, flowing mostly south and toward the Bogue Chitto, Pearl and Tchefuncte rivers, following the land surface. Well Wa-13 has varied 3 ft or less a year.
- Evangeline: the Kentwood aquifer splits into the Abita and Covington near Bogalusa. In 2003 Kentwood water levels ran from about 225 ft above NGVD 29 in the northwest to about 95 ft in the southeast, flowing southeast.
- Jasper: its base generally matches the base of the Franklinton aquifer and of fresh water. In 2006 flow in the Amite aquifer converged on a pumping center at Bogalusa, with levels from about 100 ft above NGVD 29 to about sea-level datum there; well Wa-158 has swung as much as 50 ft a year with Bogalusa's pumping.
Water levels in well Wa-13 (Upland terrace aquifer) and well Wa-158 (Amite aquifer). USGS.
Groundwater quality
The fresh groundwater is generally soft, with median chloride below 15 mg/L and dissolved solids below 175 mg/L. Temperature and color rise with depth. Iron and manganese can locally far exceed EPA's secondary (aesthetic) limits (SMCLs). Chicot and Evangeline water is slightly acidic (median pH below 6.5); Jasper water is within the 6.5–8.5 range.
| Median | Chicot (1939–2015, 45 wells) | Evangeline (1941–89, 29 wells) | Jasper (1947–83, 38 wells) | SMCL |
|---|---|---|---|---|
| Temperature (°C) | 20.6 | 21.2 | 28 | — |
| pH | 5.3 | 6.3 | 7.8 | 6.5–8.5 |
| Hardness (as CaCO₃, mg/L) | 13 | 16 | 3 | — |
| Chloride (mg/L) | 11 | 3.1 | 3.5 | 250 |
| Iron (µg/L) | <4 | 1,300 | 490 | 300 |
| Manganese (µg/L) | <0.7 | 75 | 60 | 50 |
| Dissolved solids (mg/L) | 115 | 102 | 156 | 500 |
Surface water
Most of the parish drains to the Pearl basin — the Bogue Chitto and Lower Pearl subbasins — and its southwest corner to the Liberty Bayou–Tchefuncta subbasin of the Lake Pontchartrain basin.
| Stream (gauge) | Average flow | Period | Drainage area |
|---|---|---|---|
| Bogue Chitto near Bush | ~1,994 ft³/s | 1937–2014 | ~1,210 mi² |
| Pearl River near Bogalusa | ~9,973 ft³/s | 1938–2014 | ~6,570 mi² |
| Bogue Lusa Creek at Bogalusa | 117 ft³/s | 1963–85 | — |
| Tchefuncte River near Folsom (~6.5 mi south of the parish) | ~156 ft³/s | 1943–2014 | — |
- Bogue Chitto: flows south from Mississippi, then southeast across the parish to the Pearl; tributaries include Little Silver, Silver, Hays and Lawrence creeks.
- Pearl River: forms the far-eastern Louisiana–Mississippi line, fed by Pushepatapa and Bogue Lusa creeks. In 2010, about 6.30 Mgal/d was drawn from Bogue Lusa Creek for industry.
- Tchefuncte River: part of the boundary with Tangipahoa Parish, fed by Gorman Creek.
Surface-water quality
Samples from the Pearl River (1962–94) and Bogue Chitto (1953–95) were soft and generally within SMCLs for chloride, sulfate and iron. Median pH (6.4 in both) was slightly below the 6.5–8.5 range. Dissolved oxygen was generally above 5 mg/L, the minimum for a diverse warm-water community including sport fish (medians 8.2 mg/L in both).
Sources
Based on Water Resources of Washington Parish, Louisiana, by Vincent E. White and Lawrence B. Prakken, USGS Fact Sheet 2015–3083, prepared with the Louisiana Department of Transportation and Development, U.S. Geological Survey (DOI), drawing on Sargent (2011), Griffith (2003), Nyman and Fayard (1978), Tomaszewski (2011), Prakken (2004), Fendick (2007) and USGS data; a work of the United States government in the public domain. The tables and figures come from the fact sheet's PDF.
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