A newly made stream diversion on the Huntly Bypass Project, in November 2016, and two years later in 2019 after plants have grown.
Stream diversion, Huntly bypass
Category Archives: Projects
Phosphorus loads to Lake Rotorua
What is the phosphorus load to Lake Rotorua and how much comes from human activity?
River Lake revised estimates of P loads to Lake Rotorua to account for groundwater catchment areas, geothermal inputs and long-term average loads.
This work contributed to the Science Review required by Plan Change 10 of the Bay of Plenty Regional Water and Land Plan (RWLP).
Read the report here:
Kaituna River Mixing Study
River Lake studied the mixing of diagonal drain pump station with the lower Kaituna River. We used Rhotomine dye WT to understand how well the pump station discharge mixed across the Kaituna River before the intake for the new diversion to Maketū Estuary.
The work was done for Bay of Plenty Regional Council rivers and drainage team.
Kaituna River re-diversion
The Ongatoro/Maketū estuary is a shallow, inter-tidal estuary located north of Te Puke. In 1957 the Kaituna River was diverted directly to sea and the influence of the river on the estuary was dramatically reduced. This resulted in accelerated in-filling from the
flood tide delta, loss of mussel beds, loss of wetlands and sea grass, algal accumulations and changes in the benthic fauna. The project sought to re-divert more of the river back into the estuary to improve the ecology and mauri.
River Lake provided science and planning input for the application to re-divert the Kaituna River back to the Ongatoro/Maketū Estuary. Keith co-ordinated and led the science input related to water quality and ecology. He jointly prepared a gap analysis, undertook investigations, prepared AEE reports relating to water quality and ecology and presented at the Consent Hearing and the the Environment Court.
Water quality and biota are strongly influenced by internal nutrient loads (e.g. sediments). An important part of the investigations was to quantify the likely internal loads compared to external loading predicted by the hydro-dynamic model. This involved measuring oxygen regimes and mapping algal accumulations.
View River Lakes Assessment of Effects for the Project here: Kaituna Maketu current state aquatic
Waituna Lagoon Guidelines
River Lake contributed to the Lagoon Technical Group (LTG) and Catchment Technical Group (CTG) advising Southland Regional Council on interventions to protect and restore Waituna Lagoon.
Waituna Lagoon is a highly valued, large brackish coastal lagoon and a wetland of international importance (Ramsar site). Ruppia (seagrass) is a key stone species central to the ecological functioning, of the lagoon. It is threatened by nuisance filamentous algae, sedimentation, an an opening regime that can increase salinity when the seagrass is germinating.
Our work included:
- Analysing water quality state and trends;
- Assessing the risk of the lagoon ‘flipping’ to a dirty water state;
- Contributing the the development of lagoon guidelines with quality targets for lagoon health, and management options.
Find the report here: Waituna lagoon Guidelines
Kahikatea swamp forest
Pristine kahikatea swamp forest on the Mimi River in Taranaki. Home to giant kōkopu, banded kōkopu, redfin bully and longfin eel.
Setting nutrient limits
Setting nutrient limits for complex ecosystems is challenging. We used multiple lines of evidence to set robust nutrient limits to safeguard the macrophyte community in Waituna Lagoon.
Read more in our paper on setting nutrient limits for lakes (click the link below).
Big and beautiful longfin eel
Large longfin eel caught when sampling in Donald Creek near Featherston Wastewater Treatment Plant.
Giant kokopu
One of the giant kōkopu recovered and safely relocated as part of the SH1 Huntly Bypass Project.
Longfin eel relocation, Huntly bypass SH1
