"Wetlands once covered large areas of New Zealand. Now they are some of our rarest and most at-risk ecosystems, with approximately 90 percent (by area) lost in the last 150 years due to human impact. Despite their decline, wetlands remain a vital part of Canterbury's ecosystem. They provide a haven for a vast range of native plants and wildlife, including rare and threatened species. They also offer protection against flooding and can store large amounts of carbon. This makes them essential ecosystems for protecting the planet against climate change. The small area of wetlands left need our help so that they can prosper and be enjoyed by future generations." - Environment Canterbury

In South Canterbury, the Washdyke Lagoon near Timaru has experienced a significant reduction in size since 1881, primarily due to human-induced changes affecting sediment supply. - Wikipedia

Additionally, the Canterbury Bight has faced coastal erosion rates averaging up to 8 meters per year, leading to the loss of agricultural land and reduction of coastal lagoons and wetlands in the region. -Wikipedia

These findings underscore the ongoing challenges and environmental impacts associated with wetland loss in South Canterbury.  

Combined Retrolens Historic Image by Geoff Cloeke. Sourced from http://retrolens.nz and licensed by LINZ CC-BY 3.0

Local Government Geospatial Alliance (LGGA) and Able.
Retrolens is a historic image resource containing a vast archive of aerial photographs taken across New Zealand from 1936 to 2005. It was created through a scanning project led by Land Information New Zealand (LINZ) in partnership with the Local Government Geospatial Alliance (LGGA) to preserve these valuable images before they deteriorated. The project, funded through regional partnerships, enables councils to access high-resolution imagery for land management, regulatory compliance, and cultural heritage purposes. The scanned images are available on the LINZ Data Service under a Creative Commons license, with more surveys expected to be released over time.

Imagery Re-use
Re-use of this data could be in a variety of maps, web sites, printed material and applications. All data unless specifically stated is licensed under a Creative Commons Attribution 3.0 New Zealand License. More details about Creative Commons are available here: http://creativecommons.org/licenses/by/3.0/nz/
You MUST attribute the data back to its original creator and have this license associated with the data at all times and displayed on any maps, web sites, applications or printed material using this data. Recommended Attribution: Sourced from http://retrolens.nz and licensed by LINZ CC-BY 3.0

Left, Canterbury Maps image shows the coastline in 2020. Right Image is based on land surveys and records in the Canterbury Black Maps https://mapviewer.canterburymaps.govt.nz/?webmap=0db87348adef4595a91994a3dc85cefe

Washdyke Lagoon (known in Māori as Waitarakao) is a brackish shallow coastal lagoon approximately 1 kilometre (0.62 mi) north of Timaru, South Canterbury, New Zealand. The lagoon has drastically reduced in size since 1881 when it was approximately 253 hectares (630 acres), now it is less than 48 hectares (0.48 km²) in area. It is enclosed by a barrier beach that is 3 kilometres (1.9 mi) long and 3 metres (9.8 ft) above high tide at its largest point (see Figure 1). The reduced lagoon size is due to the construction of the Timaru Port breakwater which is preventing coarse sediments from reaching and replenishing Washdyke Barrier. This is important as the lagoon and the surrounding 250 hectares (620 acres) are classified as a wildlife refuge and it demonstrates the role human structures have on coastline evolution.^{[1]  -}  https://en.wikipedia.org/wiki/WashdykeLagoon?utmsource=chatgpt.com

Left, Canterbury Maps image shows the coastline in 2020. Right Image is based on land surveys and records in the Canterbury Black Maps https://mapviewer.canterburymaps.govt.nz/?webmap=0db87348adef4595a91994a3dc85cefe

Waitarakao Washdyke Lagoon - https://www.ecan.govt.nz/get-involved/news-and-events/2020/waitarakao-washdyke-lagoon-the-past-80-years/

Waitarakao / Washdyke Lagoon is a coastal lake separated from the sea by a long stretch of mixed sand and gravel sediment, surrounded by State Highway 1, the meat works and the Washdyke industrial area.

Its importance stems from native ecological habitats, biodiversity, cultural and historical values.

For the longest time it had the perfect mix of saltwater and freshwater, allowing a diverse range of native species to thrive there.

Vist this ECan website to read:

• A history lesson
• Grant's first memories of the lagoon
• A home for precious native species
• The lagoon then and now
• A solution?
• Future steps

• European settlers significantly impacted the lagoon by building a breakwater, port, and industrial area nearby.

• The lagoon has shrunk from 250 hectares in 1881 to less than 10% of that today.

• SH1 and the main railway line prevent the lagoon from migrating landward, while the sea pushes the gravel barrier inland.

• The gravel barrier beach has retreated about 400m between 1865 and 1987 and continues to erode.

• The breakwater at the Port of Timaru has halted the natural movement of coarse sediment, starving the lagoon of protective material.

• Sediment now accumulates at South Beach and Caroline Bay, while the lagoon’s barrier erodes.

• Waimataitai Bay, north of the lagoon, disappeared entirely after similar erosion caused by the breakwater and port construction.