Benthic invertebrate response to restoration activities in Paradise Creek, Mosocw, Idaho from 1994-2014
Evan Hornig
Freshwater Bioassessment Consulting
Gary Lester
EcoAnalysts, Inc.
Executive Summary
Several stream restoration activities on Paradise Creek within the City of Moscow limits have taken place since the mid-1990s. The Idaho DEQ Beneficial Use Reconnaissance Project (BURP) has performed biological monitoring at several sites in the study reach since 1994. A look at benthic invertebrate community condition showed some improvements in relation to physical habitat restoration activities within the city limits. Upgrades to the City of Moscow wastewater treatment plant resulted in notable changes in benthic invertebrate taxonomic composition, including a reduction in pollution tolerant taxa and establishment of some pollution sensitive taxa. This presentation will discuss the biological responses to restoration activities, as well as the applicability of using BURP data to evaluate the effectiveness of such actions.
Background
The Idaho Department of Environmental Quality’s (DEQ) Water Quality Division monitors and assesses the State’s streams, rivers, and lakes. Towards this end, DEQ’s Beneficial Use Reconnaissance Program (BURP) assesses waters throughout the state on an annual basis. Fish surveys, aquatic invertebrate collections, measures of water chemistry, and records of habitat conditions are conducted in accordance with the standardized BURP protocols. DEQ applies the results of the BURP program to report on the water quality status of Idaho’s streams and lists those waters that are not attaining their designated water quality uses along with the numeric and narrative standards that indicate non-attainment. To achieve attainment, implementation plans are developed, and BURP data can be used to demonstrate the effectiveness of the implemented plans.
BURP data collected from Paradise Creek in Moscow, Latah County during 1994, 1995, and 1996 found impairment of the aquatic invertebrates and fish populations and exceedances of water quality criteria. From these results DEQ determined that Paradise Creek was not supporting the aquatic life standard designated for the coldwater streams of the Basins Region of Idaho. Using the Total Maximum Daily Load (TMDL) procedures, reductions of load capacities to meet beneficial use attainment for sediments was 75% from nonpoint sources (NPS); for phosphorus the reduction needed was 59% from NPS and 98% from the Moscow wastewater treatment plant (MWWTP); ammonia from the MWWTP needed a reduction of 77-80%; and for water temperature, a cooling in the creek from 23° C to 18°C. Although a dissolved oxygen (DO) goal is not specified for Paradise Creek, the statewide criteria for streams designated as coldwater is 6.0 ppm of dissolved oxygen (DO), and the Creek’s TMDL notes the DO concentrations drop well below this level during the summer low flow months. Maintaining sustained summer flows, cooling water temperatures through increased shading from the streamside, and limiting aquatic plant growth through lower phosphorus concentrations are means to increase DO. In 1999, DEQ developed and implemented a TMDL Implementation Plan (IP) to meet the stream’s designated use.
BURP data were collected by DEQ staff from the mid-nineties until 2013 and by EcoAnalysts in 2014. Sampling sites were located at the upstream border of Moscow; upstream, within, and downstream of restoration activities within the city; and in the vicinity of the MWWTP. The IP did not directly address stream flow or habitat as these factors are not addressed by TMDLs. However, these factors are addressed indirectly through streamside habitat restoration which reduces sediment erosion and temperatures and increases storage and retention of flood waters, thereby improving conditions needed to meet the aquatic life beneficial use.