Publications

A five-sheet hydrologic investigations atlas provides flood-peak elevation data and delineates the areal extent of flooding of the Missouri, the Mississippi, and the Meramec Rivers and the River des Peres in St. Louis and vicinity from August 1 through 3, 1993. The August 1993 flood is compared with the Federal Emergency Management Agency's (FEMA) 100- and 500-year flood profiles. This...

The first phase of intensive data collection for the National Water-Quality Assessment (NAWQA) was completed during 1993−1995 in 20 major hydrologic basins of the United States. Groundwater land-use studies, designed to sample recently recharged groundwater (generally within 10 years) beneath specific land-use and hydrogeologic settings, are a major component of the groundwater quality...

In 1986, Congress amended the Safe Drinking Water Act (SDWA) requiring the U.S. Environmental Protection Agency (USEPA) to promulgate disinfection requirements for all public-water supplies. The USEPA promulgated the Surface Water Treatment Rule (SWTR) in June 1989 to establish disinfection requirements for surface-water supplies and for ground water under the direct influence of surface...

Numerous studies are being conducted to investigate the occurrence, fate, and effects on human health and the environment from the extensive worldwide use of herbicides to control weeds. Few studies, however, are considering the degradates of these herbicides in their investigations. Our study of herbicides in aquifers across Iowa found herbicide degradates to be prevalent in ground...

No abstract available.

Water-surface-elevation profiles and peak discharges for the floods of September 15-16, 1992, in the Thompson, Weldon, and Chariton River Basins, south-central Iowa, are presented in this report. The profiles illustrate the 1992 floods along the Thompson, Weldon, Chariton, and South Fork Chariton Rivers and along Elk Creek in the south-central Iowa counties of Adair, Clarke, Decatur...

No abstract available.

Human activities have caused dramatic changes to our Nation's landscape for over a century. Use of synthetic organic compounds in agriculture and industry has resulted in the accumulation and persistence of some of these compounds in natural systems. Concern has arisen over the contamination of our Nation's waters and the organisms that depend on them.

To determine the relations between land use and concentrations of selected agricultural chemicals (nitrate, atrazine residue [atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) + deethylatrazinc (2-amino-4-chloro-6-isopropylamino-s-triazine) + deisopropylatrazine (2-amino-4-chloro-6-ethylamino-s-triazine)], and alachlor residue [alachlor, [2-chloro-2′,6′-diethyl-N-...

Since 1982, the Iowa Groundwater Monitoring (IGWM) Program has been used to sample untreated groundwater from Iowa municipal wells for selected agricultural chemicals. This long-term database was used to determine if concentrations of select agricultural chemicals in groundwater have changed with time. Nitrate, alachlor [2-chloro-2′-6′-diethyl-N-(methoxymethyl)-acetanilide], atrazine (2...

No abstract available.

A study was conducted to evaluate drawdown and volumetric changes in sources of water in the Mississippi River alluvium caused by hypothetical pumping. A steady-state, ground-water flow model was constructed for a previous study to simulate February 1993 hydrologic conditions, which were assumed to be an acceptable estimate of the ground-water system at equilibrium. The flow model was...