Case Studies

South Nevada Water Authority

April 9, 2007

South Nevada Water Authority is using LakeWatch software to provide quantitative results on the water quality of Lake Mead…

INDUSTRY: Water Supply

PRACTICE: The Southern Nevada Water Authority (SNWA) provides a water system for pumping, treating and delivering Colorado River water from Lake Mead to the Las Vegas area.

They are committed to managing the region’s water resources and developing solutions that will ensure adequate future water supplies for the Las Vegas Valley.

CHALLENGE: SNWA comprises of representatives from each of its member agencies: Boulder City, Henderson, Las Vegas, North Las Vegas, Big Bend Water District, Clark County Sanitation District and Las Vegas Valley Water District.

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Environment BOP

April 9, 2007

The Bay of Plenty Regional Council in New Zealand solves the problem of how to determine and maintain the trophic levels of its lakes using LakeWatch software…

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“LakeWatch is a much needed software tool for analyzing water quality data quickly and easily. We can see the data graphically and how it changes over time. This makes it much easier to understand the waterbody dynamics and history. It also means that we can publish interpreted data in a form that the public and policy-makers can understand at a glance.

“We use LakeWatch to give us a quantitative assessment of the trophic (nutrient, clarity, chlorophyll) level of the water. It tells us whether things are getting better or worse and how quickly. In fact, we have now adopted the Burns’s Trophic Level Index for our lakes as a planning standard to determine land use options.

“What we like about LakeWatch is that it is all done at the click of a button where previously using spreadsheets and statistical packages took much longer. We were recently contacted by the head of the Lake Tarawera Residents Association who wanted to know about the lake’s nutrient level – using LakeWatch we were able answer the question while they were still on the phone.”

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EPA SITE Program EQuIS Evaluation

May 9, 2002

Abstract: This project consisted of an evaluation of the Environmental Quality Information System (EQuIS) software designed by EarthSoft, Inc. as an environmental data management and analysis platform for monitoring and remediation projects. In consultation with the EQuIS vendor, six primary modules were tested in this evaluation. These were: Chemistry, Geology, ArcView Geographic Information System (GIS) Interface, Data Verification Module (DVM), CrossTab Report Writer, and Electronic Laboratory Data Checker (ELDC). These modules were chosen for testing because they are the most commonly used. As a part of this evaluation, a demonstration of the technology was conducted by the SITE Program at Science Applications International Corporation’s (SAIC) offices in Cincinnati and Columbus, Ohio and McLean, Virginia. The purpose of the demonstration was to determine whether the software performs the functions claimed by EarthSoft, Inc. and to assess the accuracy of the EQuIS output. In addition, demonstration results and other sources of cost information were used to develop detailed cost estimates for full-scale application of the technology.

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Lake Erie Trends in Temperature, Secchi Depth, and Dissolved Oxygen Rates in the Central Basin of Lake Erie, 1983-2002

April 23, 2002

Abstract: We examined temperature trends in a 20-year set of monitoring records collected at multiple deep-water stations in the central basin of Lake Erie. Data collected were statistically corrected (“deseasonalized”) to remove biases resulting from irregular sampling intervals within years. Depthintegrated summer temperature has increased by an average (±SE) of 0.037 ± 0.01°C per year. An observed reduction of Secchi depth (SD) by 7 ± 3 cm/y seems to be unrelated to variation in either total phosphorus (TP) or chlorophyll a concentrations. Midsummer midbasin SD values varied widely between 4 and 10 m, possibly depending on whether phytoplankton were concentrated in the epilimnion (giving shallow SD), or whether phytoplankton had settled out of the epilimnion into the lower layers, giving deeper SD values. Hypolimnetic volume-corrected oxygen depletion (HVOD) rates have also been highly variable, ranging from 2.68 to 4.72 mg/L/mo. These rates are sensitive to production of oxygen in the thermocline and hypolimnion by photosynthetically active phytoplankton that have settled from the epilimnion. The HVOD rate in any year was correlated with the previous year’s TP loading into Lake Erie. Since TP loading trends largely reflect the consequences of improving water treatment through the 1980s and increasing contributions from tributary run-off sediments through the 1990s, there is little direct evidence to suggest that the appearance of dreissenids has directly influenced hypolimnial oxygen depletion rates in the central basin. The observation that central-basin HVOD tracked the reductions in TP loadings through the 1980s may be the first affirmation that central basin hypolimnetic oxygen dynamics can be regulated by phosphorus inputs. This implies that TP loads must continue to be regulated if we wish to minimize oxygen depletion rates as a strategy to reduce the frequency of episodic central basin anoxia.

Full PDF follows.

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