Incidence and Timing of Low Dissolved Oxygen Events in the Squamscott River: 2005-07

The Squamscott River has had extended episodes of low dissolved oxygen (DO) that have been recorded at a site near its mouth during the past few years. These episodes were recorded as a result of temporally intensive monitoring by a datasonde deployed through most of each year. Whereas low DO events can occur during April-November, events during the colder months are typically less frequent and are often caused by unusual natural or severe weather conditions. Low DO events occur most frequently during July-September when elevated levels of nutrients are most likely to contribute to their cause, and are thus of most concern. The study found the warm season time period of July-September to be the time of year when low DO events were most frequent and pervasive. In comparisons between each year from 2005 to 2007, 2005 had less frequent and pervasive low DO events compared to 2006 and 2007. Relative to tidal cycle conditions, low DO conditions were most likely to occur during neap tide conditions, as indicated by the least shallow depth readings for the data sonde. Beyond the seasonal and tidal time periods, the time of day where conditions are most likely to cause low DO events is also critical for focusing field efforts. The most frequently observed time of day when either a low DO event was initiated or the lowest DO reading was recorded was in the morning, especially before 8:00 AM. Much less frequent occurrence of these events was observed during the second half of days. It appears that the predicted conditions for conducting water measurements and sampling during 2005 were relatively accurate. The study should have been more successful except that 2005 was a year in which low DO episodes were less frequent and pervasive. Future studies in the Squamscott River area near the data sonde can benefit from use of the results reported herein. The same kind of analysis could also be used to help inform studies in other areas of the estuary where data sondes are nearby and have available databases for water quality conditions

Tracking Bacterial Pollution Sources in Stormwater Pipes

The New Hampshire Department of Environmental Services (DES) conducted two rounds of wet weather sampling in the Hampton Harbor watershed during 2002. Samples were collected from stormdrains, tributaries, and harbor stations for bacteria and flow in order to calculate bacteria loads. This information was needed to prioritize pollution sources as part of a Total Maximum Daily Load (TMDL) study of bacteria in Hampton Harbor (Trowbridge, 2003). Two of the 16 monitored stormdrain pipes were selected for microbial source determination using ribotype profiling. Stormdrain pipe selection was based on the bacteria loading data from the first wet weather sampling that occurred on 7/23/02. The two sampling sites identified as HHPS069 and HHPS182 contributed 12% and 60%, respectively, of the bacteria load from the 16 monitored stormdrains during the first storm event. It was determined that these two pipes would be targeted for more intensive investigations based on the high relative loading of bacteria. Thus, samples were collected during a second storm on October 16, 2002 from these two pipes and analyzed for source species identification using ribotype profiling

Tracking Bacterial Pollution Sources in Hampton Harbor

Fecal-borne microorganisms impact many shellfish-growing waters in coastal New Hampshire. Watersheds are often subject to fecal contamination by a variety of sources and efforts to improve water quality are often limited because of lack of information on which contaminant sources are most significant. Ribotyping and other microbial source tracking methods are useful new tools for providing information on the sources of fecal-borne bacterial contaminants in surface waters. New Hampshire has areas of abundant oyster (Crassostrea virginica) and clam (Mya arenaria) resources, the latter being most important in Hampton Harbor. In this study, Escherichia coli isolates (bacteria colonies) were obtained from water samples collected from ten sites in Hampton Harbor year-round during both dry and wet conditions. A library of known E. coli isolates was created from twenty different potential source species in the New Hampshire coastal watershed, including humans, livestock, pets, wildlife and avian species. The ribosomal RNA DNA of E. coli isolates was analyzed using ribotyping in which the patterns of ribosomal DNA were detected using chemiluminescence, then optimized and analyzed using GelCompar II software. A total of 249 isolates from the twenty known source species were used as a reference to identify sources for 390 unknown isolates from water samples taken from August 2000 through October 2001. Banding patterns for water samples and source species isolates were considered to be the same if there was 80% or greater similarity between patterns. Overall, sources for 62% of the isolates were identified

Low Impact Storm Water Management Projects at the University of New Hampshire

The University of New Hampshire has become increasingly concerned with storm water management on the Durham campus. Due to Federal regulations many regional municipalities are feeling pressure to enhance and increase management of storm water to reduce impacts to surface waters. The specific objective of this proposal is to demonstrate reductions in the discharge of storm water runoff from UNH-Durham campus properties. The construction and use of three Low Impact Development (LID) integrated management systems on UNH property will help UNH and the UNH Stormwater Center to champion innovative approaches in the state and region for reducing storm water runoff and improving the health of coastal watershed areas

Evaluating the Stormwater Treatment Performance of AbTech Industries Smart Sponge® Plus, Landry, N

The ability of AbTech’s Smart Sponge® Plus to remove fecal-borne bacteria from stormwater was evaluated in a storm drainage system located in Seabrook, New Hampshire. The Smart Sponge ® Plus was installed into a water quality inlet and samples were collected from influent (pre-treatment) and effluent (post-treatment) for analysis of bacterial concentrations and loadings during 15 storm events from September 3, 2003 to May 24, 2004, excluding winter months. The 15 storms included events with a range of rainfall intensities and amounts, as well as accompanying runoff volumes. Flow weighted composite samples were analyzed for fecal coliforms, Escherichia coli and enterococci to determine if concentrations were lowered as stormwater passed through the Smart Sponge® Plus material. In most cases, bacterial concentrations were reduced within the treatment system, but to varying degrees. The efficiency ratio based on reduction in event mean concentration for each bacterial indicator in the flow was calculated for each storm event. The values ranged most widely for fecal coliforms, whereas the range of ratios was narrower and the values were more consistent for enterococci. The overall load reductions for the bacterial indicators were 50.3% for fecal coliforms, 51.3% for Escherichia coli and 43.2% for enterococci. Relatively consistent pH values were observed in influent and effluent samples. The overall range of pH values was large, ranging from 5.21 units in influent from storm event #11 to 7.64 units in influent from storm event #1. Conductivity values were gr eater in the effluent in 14 of the 15 storm events, especially in storm events #12 and #13 when effluent conductivities were \u3e50% higher than influent values. Quality assurance/quality control procedures supported the methods and results of the study. Overall, the observed reductions in bacterial concentrations in post-treatment stormwater would still result in discharge of elevated bacterial levels that would continue to limit uses in receiving waters

Evaluation of Effects of Wastewater Treatment Discharge on Estuarine Water Quality

This report marks the completion of a two-year project focused on observed and estimated effects of wastewater treatment facilities (WWTFs) on estuarine water quality within the New Hampshire (NH) Seacoast region. This study was designed and carried out in an effort to help the NH Department of Environmental Services (NHDES) and NH Estuaries Project (NHEP) evaluate the effects of WWTF effluent quality on bacterial and nutrient concentrations in New Hampshire’s estuarine waters, as well as to help NHDES/NHEP identify related WWTF infrastructure problems. An extensive database of bacterial and nutrient concentrations in effluent collected post-disinfection from 9 NH WWTFs and 2 Maine WWTFs that discharge into the Great Bay and Hampton/Seabrook estuaries was developed. The data were used to determine ratios between different bacterial indicators in WWTF effluent, estimates of in-stream bacterial concentrations following effluent discharge to receiving waters and estimates of nutrient loading from selected WWTFs